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A newly developing method, rock surface luminescence dating, provides a novel means of constraining the burial age of fluvial gravel and unveiling the transport and exposure-burial process of fluvial bed-load. A crucial requirement for successful age determination in luminescence dating of buried rock surfaces is that a sufficiently thick surficial layer was reset to a near-zero level of signal prior to deposition and burial. However, little such effort has been made on modern fluvial gravels from various depositional environments to provide a sound justification for the use of luminescence dating in such settings. In this study, we reported an investigation of daylight bleaching in modern cobbles with different sizes and shapes at a modern river floodplain from the Manas River, Tian Shan, to test the reliability and applicability of fluvial cobble optical dating. Four multi-elevated-temperature post-infrared infrared (MET-pIRIR) stimulated luminescence signals of rock slices were measured using a modified MET-pIRIR protocol to establish residual luminescence-depth profiles. The residual does of pIRIR and MET-pIRIR signals of sub-surface rock slices were also estimated using different modified SAR protocols. The results showed that the high temperature IRSL signal could be reset to ∼2–3 mm depth into cobbles surface and flat cobbles seem easier to bleach than spherical cobbles. The residual doses of sub-surface rock slices of cobbles from modern river floodplain was ∼0.4 Gy and ∼1.1 Gy for the IR 50 and the pIRIR 170 signal respectively, suggesting a residual age of ∼0.1 ka and ∼0.2 ka. The residual ages of MET-pIRIR signals of sub-surface rock slices of cobble MNS2-5 were ∼0.5–1 ka at higher stimulation temperature. Our results show that the fluvial cobble optical dating techniques have great potential for providing reliable chronologies for river floodplain gravel and other fluvial depositional events. [ABSTRACT FROM AUTHOR]

• Devonian-Carboniferous sedimentation and paleoenvironments along the Iberian Pyrite Belt are analysed. • Several stratigraphic hiatuses are identified and confirmed in the Neves-Corvo region. • Palynostratigraphy is an important tool to define the age of the black shales hosting the mineralization. • IPB bioevents related to the major extinction event and environment changes are documented in the Devonian-Carboniferous Boundary. • Improvement of the stratigraphy of the IPB and geological knowledge. Based on drill hole sampling and sedimentary rock dating by palynology, the present research focuses on the palynostratigraphic events established in the key geological section of Guedelhinha–Lançadoiras–Algaré located in the Portuguese Neves–Corvo mine region, Iberian Pyrite Belt. The age data allow detailing the lithostratigraphic sequence and further understanding the complex structural setting, representing an important contribution to the geological knowledge of this sector located to the immediate WNW of the Neves–Corvo VMS deposit. The combination of the studied events allows the reconstruction of the Devonian-Carboniferous sedimentation and paleoenvironments along the Iberian Pyrite Belt. Several stratigraphic hiatuses identified in the Neves–Corvo region by the palynological record are confirmed, mainly occurring from the mid Frasnian to mid Famennian, from the early and mid Strunian, and from the early to late Tournaisian, which were mainly coincident with the worldwide extinction events, in particular during Frasnian–Famennian and Late Devonian times. Extensional tectonics and related gravitational faults, local uplift mechanisms and intense volcanic activity could also explain the lack of palynological data and sedimentary hiatus. In this research, the importance of the late Strunian times in the Iberian Pyrite Belt (Miospore Biozone LN of the Neves Formation) is highlighted, confirming the contemporaneity of felsic volcanism, hydrothermalism, sulphide mineralization precipitation and black shale anoxic sedimentation. [ABSTRACT FROM AUTHOR]

Miocene petrified tree fossils in tuffs from Lesvos Island show a variety of types of mineralization. Trees from the older part of the volcanic succession, including the well-known Petrified Forest near Sigri, are brilliant yellows, reds and browns as a result of Fe–Mn hydrothermal alteration post-dating silicification. Trees from the younger part of the volcanic succession on the southeastern flank of the volcanic chain include some in which the original carbon has not been replaced, others that are completely silicified or completely replaced by calcite, and yet others with cell walls silicified and the lumina filled with a variety of carbonate and sulfide minerals. Widespread Fe–Mn hydrothermal veins are found only in the older part of the volcanic succession and in underlying basement rocks and date from the inversion of the Sigri basin in the mid-Burdigalian and the intrusion of the Mesotopos dykes and laccoliths. The variable petrifaction of fossil wood is thus essentially a consequence of the variability of diagenetic and hydrothermal processes. This study demonstrates the importance of tectonic history in localising volcanic hydrothermal circulation and hence diversity in style of petrifaction. • Silicified trees in tuffs in western Lesvos show late Fe–Mn mineralization. • Mineralization at depth after basin inversion and laccolith intrusion. • In tuffs in eastern Lesvos, incomplete tree petrifaction by silica and/or carbonates. • Mineralization at shallow depths, no basin inversion, some basement leaching. • Petrified trees provide record of diagenetic and hydrothermal history of host tuffs. [ABSTRACT FROM AUTHOR]

A technique for parameterizing rock surfaces for luminescence surface exposure dating involves the use of known age rock surfaces which may host no surficial alterations or weathering rinds. However, exposure dated rock surfaces often host subsurface weathering rinds or foreign surficial components, which may impact the development of luminescence depth profiles in the rock material. To observe any effects of depth profile development and parameterizations of naturally altered rock surfaces, controlled exposure experiments were conducted on surface altered and surface non-altered luminescence saturated quartzite samples from the top and bottom portions of rock surface cores, collected from two erratic members of the Foothills Erratics Train, Alberta. Spatially resolved OSL laser scanning techniques were used to acquire two-dimensional OSL maps of the surface core samples for depth profile generation. Results produced varied intensities of depth profile data scatter and depth profile parameterizations between surface altered and non-altered samples. Several cores which exhibited surface alterations produced lower attenuation coefficients than comparable cores with no surface alterations, possibly from the effects of surface features and weathering rinds attenuating light intensity for OSL stimulation. These trends indicate samples hosting surface alterations such as weathering rinds, lichen cover, and staining may offer parameterizations which are inequivalent to rock surfaces with no surface altered components, and that depth dependent, multi-order parameterizations may be needed to adequately parameterize rock surfaces hosting surface altered features for exposure dating. • Spatially resolved OSL maps are produced from weathered and nonweathered quartzite surfaces. • Lower light attenuation values are generally fitted from weathered surface samples. • Weathering rinds, surface coverage may reduce OSL bleaching deeper into the subsurface. [ABSTRACT FROM AUTHOR]

The coupled ESR and U-series (ESR/U-series) method has been increasingly utilized for dating fossil teeth from Early to Middle Pleistocene hominid sites. One significant advantage of this method is its ability to directly analyze fossil animal or human teeth. However, compared with other radiometric methods such as 14C charcoal dating, U-series carbonate dating, and OSL sediment dating, this dating method is rarely employed for Late Pleistocene or younger sites. In this study, we present an ESR/U-series dating investigation conducted at the Naminan site, a Paleolithic-Neolithic transition (P–N transition) site situated on the Sino-Myanmar border. The ESR/U-series analysis of eleven dental samples yields an age range of 18.1–13.2 ka for the fossils. These obtained ages are generally consistent with the 14C chronology of the site. When dealing with young fossil samples, it was observed that due to relatively low uranium concentration in dental tissues, internal dose rate plays a less significant role compared to external beta and gamma dose rates in the total dose rate of the fossil samples. Consequently, evaluating the dose rate of surrounding sediment becomes a primary source of uncertainty. Additionally, in this study we attempted to employ the standardized growth curve (SGC) and representative dose response curve method for determining Equivalent Dose (D E), which was then compared with values obtained using additive dose method (ADM). Although the precision of D E estimated by two methods are comparatively lower than that of ADM, it demonstrates the potential to efficiently determine a more rational D max for irradiation, identify samples with stratigraphic disturbances, and analyze small or valuable fossil specimens. • Coupled ESR/U-series method was first applied to a P–N transition site in China. • SGC were tested to determine the D E of Late Pleistocene fossil samples. • The fossil ages calculation was independent with different U-models. [ABSTRACT FROM AUTHOR]

The existing radiocarbon (14C) dating framework for Lagar Velho is broadly consistent but provides limited constraint on several geoarchaeological complexes (GCs) and does not favour detailed chronological comparisons across all sectors of the site; including the stratigraphically disconnected child burial complex in the east area and the broader archaeological sequence in the central-west area. In this study, we undertake a complementary chronological assessment of Lagar Velho Rock Shelter using single-grain quartz OSL, single-grain quartz TT-OSL and combined U-series/ESR dating of fossil teeth, with the aim of establishing more comprehensive reconstructions of archaeological events and placing the human occupation sequence in a firmer regional climatic context. Expanding on the original chronological study, we also compare the published 14C datasets against widely used sample quality indicators (i.e., organic preservation and contamination proxies) to ensure reliable comparisons with our new luminescence and combined U-series/ESR ages. Eight 14C samples pass our combined chronological and stratigraphic hygiene criteria and are included in the final dating evaluations. Ten of the twelve optical dating samples produce homogeneous equivalent dose (D e) datasets indicative of suitable daylight exposure. The replicate single-grain TT-OSL D e datasets exhibit more pronounced scatter, consistent with enhanced potential for insufficient bleaching of TT-OSL residual doses in some karst settings. The fossil enamel samples dated using U-series/ESR span relatively low natural dose ranges, necessitating the inclusion of maximum dose (D max)-adjusted dose response curve fitting and additional background noise subtraction to avoid D e biases of up to 13%. Stratigraphically consistent ages (n = 26) spanning the full archaeological infill sequence are obtained using the four different dating methods, providing a robust interpretive framework and underscoring the significant role of single-grain OSL and combined U-series/ESR dating for refining early Upper Palaeolithic histories of Iberia. Bayesian modelling of the combined chronological dataset reveals a site accumulation history spanning 35,750–23,440 cal. BP and provides improved age constraints on all GCs; particularly the al , bs , tc , gs and ls deposits that were previously undated or imprecisely constrained. The age of the child burial complex is refined to 29,410–28,280 cal. BP, potentially occurring within Greenland Interstadial 4. Comparison of the modelled GC ages from the east and west-central areas enables improved temporal correlations of depositional events across stratigraphically disconnected sectors of the site. This analysis suggests that the child burial complex and the Late Gravettian occupation are statistically indistinguishable based on current dating evidence. The new dating assessments reveal three periods of human occupation at Lagar Velho: the Late Gravettian (including the shorter duration child burial event) 31.6–26.0 ka from the end of Heinrich Stadial (HS) 3 until the emergence of HS2; the Terminal Gravettian 26.5–24.5 ka coinciding with HS2; and the Middle Solutrean 25.2–23.4 ka extending from HS2 to the end of Greenland Stadial 3. The timing of these occupations during late Marine Isotope Stage (MIS) 3 and early MIS 2 highlights the significance of central western Portugal for supporting regional human populations during periods when much of Europe was experiencing extreme cold, aridity and expanded glacial coverage. • Consistent OSL, TT-OSL, US-ESR and 14C ages obtained for the archaeological sequence. • Bayesian modelling reveals site accumulation history spans 35,750–23,440 cal. BP. • Child burial age refined to 29,410–28,280 cal. BP, potentially within GI4. • Three human activity phases correspond with short-term climate cycles in MIS2. • Central-west Portugal was a key refugium for human populations during HS2 and LGM. [ABSTRACT FROM AUTHOR]

While flint and similar materials are some of the most often preserved finds from the pre-historic archaeological records, trapped charge techniques can currently only be used on heated flint pieces. Here, we investigate if rock surface luminescence dating using the light-sensitive OSL signal is applicable to unheated flint nodules and cobbles by measuring OSL signal-depth profiles in flint samples collected from eastern Zealand and Møn, Denmark. We demonstrate that a detectable, natural OSL signal is present in the centre in eight out of the nine investigated flint samples. Additionally, the OSL signal had been bleached to various depths at the flint surfaces, which were exposed to daylight at the time of sampling. The field-saturated OSL is 50% or lower compared to the laboratory OSL after a 6 kGy dose was administered to field-saturated flint slices; this discrepancy could be related to signal loss occurring over geological time scales, but the exact nature of the mechanism of signal loss remains unclear. The presence of a natural OSL signal that bleaches into the flint when exposed to daylight suggests that rock surface dating of unheated flints is feasible, and the method should be further tested on known-age samples. • Natural OSL is observed in geological flint from chalk deposits. • OSL-depth profiles from flint surfaces show signal bleaching when exposed to daylight. • Comparison between field-saturated and laboratory-saturated OSL in flint provides insight into OSL signal stability. • Early signal subtraction reduces the scatter in OSL-depth flint profiles. [ABSTRACT FROM AUTHOR]

Here we report luminescence dating results on exhumed fault rocks from the North Tehran Fault (NTF, Iran), including the fault gouges. The NTF is an oblique-dip thrust fault expanding from west to east at the northern fringe of the megacity of Tehran. Although the fault is known to be active and a major threat to the city, only little is known about its earthquake history. We present first data on the timing of past fault motion using dating of fault rocks. Three sites have been selected for this study in which the fault damage zone is associated with Eocene volcaniclastic rocks (Karaj Formation). The fault gouge, transitional and damage zone were sampled for which we observed slip planes in the field. The fault rocks are composed of quartz and alkali feldspar favourable for luminescence dating. However, our study reveals that the quartz optically stimulated luminescence (OSL) signal of the Karaj Formation does not seem to have a measurable fast decaying signal component. Instead, the post-infrared stimulated luminescence at 225 °C (pIRIRSL 225) of polymineral fine-grain fraction appears to be the most feasible signal for these samples. The first luminescence-based results presented here comprise an age range from 45 ± 5 ka to 72 ± 13 ka for fault gouges and transitional zone. Since dating the transitional zone close to the fault gouge led to a younger age than the fault gouge at one site, we conclude that the sampling location plays a crucial role in dating exhumed fault rock using luminescence dating. The obtained ages are far older than those of the previous palaeoseismological studies that dated earthquake-related sedimentary features in the region. Therefore, more research is required to shed light on the resetting mechanism and condition of these fault rocks due to the recent activity of the NTF. [ABSTRACT FROM AUTHOR]

• Drill core samples constrain the age and evolution of the buried Wyoming Province. • Zircon U-Pb geochronology records Mesoarchean magmatism and metamorphism. • Reflector east of the Bighorn Mountains may juxtapose Archean terranes with similar ages and isotopic signature. • Geochemical, geochronologic, and geophysical data are most easily explained by a contiguous eastern Wyoming Province. • Integration of geologic, geochemical, geochemical, and geophysical datasets is critical to evaluate Archean and Proterozoic terrane boundaries. The extent and nature of the Wyoming Province, an Archean craton in southwestern Laurentia, are poorly understood due to limited exposure between spatially isolated basement-cored uplifts. This lack of exposure has led to debate about whether the northeastern Wyoming Province is underlain by contiguous Archean crust or Proterozoic rocks and suture zone associated with the Trans-Hudson orogeny. To assess these models we analyzed samples recovered from drill cores in the buried northeastern Wyoming Province that straddle the proposed Proterozoic suture. Whole-rock geochemical and Nd-Pb-O isotopic data suggest the rocks formed by partial melting of > 3.5 Ga hydrated mafic to tonalitic sources similar to elsewhere in the northern Wyoming Province. Zircon U-Pb dates record Mesoarchean magmatism and metamorphism (3.0–2.8 Ga). Published whole-rock Rb-Sr, hornblende and biotite K-Ar, and apatite fission track dates suggest these rocks have not been heated above 300 °C since 2.5–2.1 Ga. Geophysical potential field data are consistent across northeastern Wyoming contrasting with major discontinuities associated with documented Proterozoic orogens on all other margins of the Wyoming Province. Hence, geochemical, isotopic, and geochronologic data along with geophysical imaging can be most simply interpreted in terms of continuous Archean crust in the northeastern Wyoming Province. A geophysically-imaged reflector east of the Bighorn Mountains may juxtapose Archean terranes with similar ages and sources, similar to the boundary between the Montana metasedimentary terrane and Beartooth-Bighorn magmatic zone in the northwestern Wyoming Province. This work emphasizes the value of integrating geologic and geophysical constraints to constrain Archean provinces and their tectonic evolution. [ABSTRACT FROM AUTHOR]

The paper presents the lithological and chronometric data (15 new and 9 earlier published dates) obtained in 2018–2020 on the Upper Pleistocene sections along the Terskiy and Zimniy Coasts of the White Sea. Focused on the Lower Weichselian (MIS 5d-a) and lower Middle Weichselian (MIS 4) sediment successions, the marine and glacial events are discussed. Marine environment was reconstructed in the White Sea basin, and water exchange between Barents and White Seas via Gorlo Strait. In the presented sedimentary succession, the sandy units dated to 72–66 ka and 63.5–53.5 ka on the Terskiy Coast and to 61–52 ka on the Zimniy Coast were associated with the Mezen marine transgression. Glacial event during MIS 4 is suggested in the north-easternmost shore of the White Sea, where the Barents Ice Sheet expanded from the Kara and Barents Seas shelf and reached the eastern coast of the Mezen Bay. The Terskiy Coast (southern Kola Peninsula) seems to be affected by local glacial sheet during the early Middle Weichselian. [ABSTRACT FROM AUTHOR]

Rock art is found in many different regions of the world, with ages dated from late Palaeolithic period to the present. However, determining the precise ages for such artworks with direct chronological methods is challenging. U-series dating of secondary carbonates can constrain the age of rock art if these carbonates stratigraphically connected to the art. Hitherto, U-series isotope-dilution analyses with multi-collector inductively-coupled plasma mass spectrometry (ID-MC-ICPMS) has been increasingly used for rock art dating. This approach can achieve U–Th isotope-ratio quantification at the per-mille or submille level, but requires chemical pretreatment using isotope spikes and results in a relatively low sampling resolution. While in situ U-series dating using laser ablation-MC-ICPMS (LA-MC-ICPMS) is significantly less precise than ID-MC-ICPMS analysis, it allows to collect spatially resolved data sequences on very thin samples (<1 mm). This is important for identification of open systems and the chronological integrity of the analyses. Therefore, we developed a new method for high spatial resolution U-series in situ analysis. A piece of homogeneous stalagmite was selected as an in-house standard (RM-C1) for U-series in situ dating analysis. RM-C1 contains high U (17.3 ± 1.0 μg/g) and low Th concentrations (<5 ng/g). The 234U/238U and 230Th/238U activity ratios of 1.0116 ± 0.0006 and 0.9525 ± 0.0013, respectively, corresponding to a U-series age of 303.5 ± 1.5 ka, were determined by the ID-MC-ICPMS analyses (n = 10). Using the RM-C1 standard, we were able to date the Dansgaard–Oeschger (D/O) 19 event (with an expected age of 68.9 to 70.3 ka) in a stalagmite to a range from 68.0 ± 2.0 to 71.2 ± 2.5 ka, with an average age of 69.6 ± 1.5 ka (n = 15). This demonstrates the accuracy and reproducibility of our dating protocol. Subsequently, we conducted U-series in situ dating of secondary carbonates associated with rock paintings with two samples from the Cangyuan shelter (CY2-4 and CY2-7) and two samples from the Wanrendong Cave (SL3-A and SL5-A) in Yunnan Province, southwestern China. These samples had high U-concentration (>4 μg/g) and negligible environmental Th. The carbonate layers immediately overlying the pigments of CY2-4 and CY2-7 were dated to 3.7 ± 0.3 and 3.2 ± 0.2 ka, respectively, suggesting that the Canyuan rock paintings belongs to a late Neolithic culture of this area. The pigment layer sandwiched in the sample SL3-A was bracketed to between 8.7 ± 0.3 and 10.1 ± 0.3 ka and in SL5-A to between 10.4 ± 0.3 and 10.8 ± 0.4 ka, implying that the Wanrendong rock paintings probably were created by a hunting-gathering population during the early Holocene. [ABSTRACT FROM AUTHOR]

The eastern flank of the Talesh range of western Alborz, northwestern Iran, exposes volumetrically significant Late Cretaceous volcanic and volcaniclastic associations as well as cross-cutting dykes and minor subvolcanic equivalents. The volcanic units appear as massive to pillowed flows interlayered with volcaniclastic beds and subordinate limestones. We present new field data, zircon U Pb ages, bulk-rock major and trace element geochemistry, and Sr Nd isotopes on the igneous rock suite. Geochemical data show that the lava units and dykes are mainly basaltic in composition with minor basaltic andesites and trachytes. They form two contrasting series of arc-related calc-alkaline (Group 1) and OIB-like (Group 2) rocks. The zircon U Pb age of Group 1 rocks is 95.6 ± 1.8 Ma (2σ), whereas for Group 2 rocks, cross-cutting relationships and stratigraphic constraints indicate a somewhat younger age. Group 1 rocks have 87Sr/86Sr (i) varying from 0.7038 to 0.7070 and ε Nd (t) values ranging from +0.5 to +5.0. Group 2 rocks have 87Sr/86Sr (i) = 0.7040–0.7065 and ε Nd (t) from −3.0 to +3.7. Trace element and isotopic modelling shows that the primitive Group 1 magmas were derived from a metasomatized mantle source enriched by the addition of ∼6–10 % sediment melt component, while Group 2 rocks are consistent with melts of an asthenospheric mantle source enriched by ∼1–5 % EMII component. Trace element modelling indicates that Group 1 rocks formed from ∼6–13 % partial melts of a spinel-garnet lherzolite with garnet:spinel ratios of 45:55 to 10:90, whereas primitive Group 2 melts were generated through ∼1–3 % partial melting of a garnet-spinel-lherzolite with garnet:spinel ratios of 90:10 to 80:20. We propose a geodynamic model in which a north-dipping Neotethyan slab beneath the western Alborz (Talesh area) continental margin produced arc assemblages of Group 1 rocks and subsequent slab rollback led to the upwelling of an asthenospheric mantle to generate OIB-like magmatism of Group 2 rocks in an extensional intra-arc to back-arc setting. [Display omitted] • The Talesh magmatic rocks are dominated by basaltic lavas. • They were emplaced during the Late Cretaceous. • The magmatic rocks include both arc-type calc-alkaline and OIB-like alkaline rocks. • The mantle source of arc-type rocks was enriched by slab-derived sediment melts. • Slab rollback triggered asthenospheric melting and formation of OIB-like magmas. [ABSTRACT FROM AUTHOR]

Recent research on Later Stone Age (LSA) San rock art in southern Africa has unveiled some of the paint recipes the artists employed. However, these discoveries still need to be linked to human activities in or near the rock shelters where the paintings were made. In this paper, we report characterization and dating results from the catchment of the Metolong Dam, Phuthiatsana Valley, Lesotho. A total of 92 rock painting samples, six grindstones with traces of colouring materials from an excavated context, and 17 potential raw colouring materials were studied. We identified three previously unreported ingredients used by the artists: manganese oxides, calcined bones, and soot. Grindstones are stained with the same raw materials that the painters used. We propose that one of them may have served to prepare the red pigment used to make a human figure and a bichrome eland at Ha Makotoko, but direct links remain difficult to establish with certainty. The potential colouring materials in the valley are red clays, white clays (kaolinite and illite-or-montmorillonite), and gypsum, three compounds used as paints by the artists. Tests conducted to verify their suitability for paintings show these materials may have been ground, but settling (after pre-grinding) offers a quicker and easier way to obtain a fine powder as observed in the paints. Finally, 12 AMS dates provide an initial framework for studying the changing use of paint recipes in the Phuthiatsana Valley over time. Charcoal appears to have been employed over a period of at least 3000 years and carbon black for at least 2000 years, with soot seemingly used only before 2000 cal. BP. This study is currently the largest characterization and dating study of LSA rock art in southern Africa and shows the potential that such combined investigations offer for linking excavated and parietal components of the region's hunter-gatherer archaeological record. [ABSTRACT FROM AUTHOR]

40Ar/39Ar geochronology is one of the most important techniques for constraining the timing of basaltic events due to the paucity of suitable minerals in basalts for other geochronological techniques such as U–Pb (e.g., zircon, baddeleyite). Among a variety of materials from basaltic rocks that have been used for 40Ar/39Ar dating, plagioclase is the most important due to its common presence in basalts as a primary crystallizing phase, and its transparency so that fresh grains can be selected during sample preparation. However, plagioclase 40Ar/39Ar geochronology has often been compromised by alteration (e.g., sericitization by hydrothermal events), which, in practice, is difficult to identify using a petrographic microscope when the amount of alteration is low (e.g., <1%). We used laboratory step-heating experiments and theoretical simulations to characterize the 40Ar/39Ar age and Ca/K spectra of altered plagioclase so that 40Ar/39Ar dating results on altered samples can be identified and better interpreted. The step-heating experiments and theoretical simulations yielded consistent results, and show that with the presence of even a tiny amount of sericite (~0.01% for K-poor samples and ~0.1% for K-rich samples), the plagioclase samples yielded alteration plateau ages that are 3%–4% younger than the crystallization age. The difference between the alteration age of sericitized plagioclase and its crystallization age is primarily controlled by the time lapse between the crystallization and sericitization events, but also by the Ca/K ratios of the plagioclase. For plagioclase samples that experienced the same alteration event, the higher the Ca/K ratio is, the more sensitive the 40Ar/39Ar age is to alteration. We propose that the alteration signatures of plagioclase can be effectively identified through inspecting the 40Ar/39Ar age spectra, the Ca/K spectra, and the degassing curves. We also investigated the effect of sericitization of plagioclase microliths in basaltic groundmass and modelled the 40Ar/39Ar age and Ca/K spectra of altered groundmass samples. We validate our approach by revisiting published 40Ar/39Ar dating results for large igneous provinces, and showed that these dates should have been interpreted as alteration ages (minimum eruption ages) rather than crystallization ages. Finally, we demonstrate that with high degrees of alteration (~50% for K-poor and >70% for K-rich plagioclase samples), the age of hydrothermal alteration can be successfully dated. [ABSTRACT FROM AUTHOR]

Tham Wiman Nakin or "Snake Cave" has so far been recognized as being the only late Middle Pleistocene Homo -bearing fauna, dated to older than 169 ka, in mainland Southeast Asia. Since the last two decades, the highly diversified mammal fauna found from this cave has been widely used as standard references for several studies, though the majority of fossil primates, carnivores, and ungulates have never been described in detail. This paper presents taxonomic descriptions of unpublished fossil specimens from the long-known collection of Tham Wiman Nakin. As a result, the fauna of Tham Wiman Nakin consisted of at least 28 large mammal taxa. Although several previously described specimens are re-assigned to different tooth elements and/or mammal taxa, our taxonomic study confirms the existence of most of the species identified from the previous work and describes three additional taxa for the locality: an Asian badger, a tiger, and a Himalayan goral. The Tham Wiman Nakin fauna is one of the most diverse Pleistocene mammals, including a hominin, in mainland Southeast Asia and documents long-term survivors of living species since the late Middle Pleistocene. Based on several recent dates of fossil sites in mainland Southeast Asia, biochronological data imply a possible faunal age up to the maximum of 300 ka for the Tham Wiman Nakin fauna, but younger than that of Pha Bong where Gigantopithecus was present. Fossil records in the region also suggest a relatively stable fauna through Pleistocene glacial-interglacial cycles, at least from the late Middle to latest Pleistocene. The extinction occurring in the mainland varied across taxa and likely resulted in less impacted biodiversity loss prior to the Holocene, compared to other continents, as indicated by the small proportion of species becoming extinct during each interval. The importance of stable mosaic habitats through time may provide clues to the long-term survival of several large mammal taxa in the region. [ABSTRACT FROM AUTHOR]

Pleistocene vertebrate faunas have long been known from the island of Timor but have rarely been studied. In particular, dwarf elephant-like proboscideans such as Stegodon were once widespread across the island, including to the Atambua Basin, but the cause of their extinction is unknown. Here, we document the fossil Pleistocene fauna of this basin with their palaeoenvironmental context. We also investigate the possibility of human- Stegodon chronological overlap. Our methods include field survey, excavation, pollen analysis, and U-series dating. Palaeoenvironmental data based on geomorphology and hydrological information show a transition from marine to fluvial depositional conditions in the basin during Pleistocene. Pollen data supports this interpretation and shows a clear shift from mangrove to terrestrial vegetation types. Palaeoclimatic conditions after the transition are characterized by a high humidity with high-flow water across the basin. Fossils of vertebrate faunas are restricted to fluvially-derived sandstone units. Meanwhile lithic artefacts were recorded widely across the basin, in the from of surface finds. There is so far no example of direct association of lithic artefacts with extinct Pleistocene faunas. Direct dating of the vertebrate fossils suggest they came from the Middle Pleistocene or earlier, and consequently pre-date the oldest current records of modern human existence on the island ~45,000 years ago. [ABSTRACT FROM AUTHOR]

• First in-situ apatite U-Pb ages from pseudotachylytes. • The lower crust fails seismically during the early stages of continental collision. • Earthquakes create long-lived fluid pathways in the lower crust. Determining the precise age of fossil earthquakes is essential for understanding the tectonic setting in which they occurred. Pseudotachylytes are quenched frictional melts that occur along coseismic fractures and represent evidence of fossil earthquakes in the rock record. Here, we present the first in-situ apatite U-Pb ages for three samples from Lofoten in the northern Norwegian Caledonides, that occur within and adjacent to lower-crustal pseudotachylytes: a pristine pseudotachylyte, a mylonitized pseudotachylyte, and a mylonite that contains pseudotachylyte transposed into the shear plane. The apatite U-Pb ages are combined with cathodoluminescence and electron backscatter diffraction analysis to provide microstructural constraints on the interpretation of ages. Apatite shows evidence of either fragmentation and annealing, or dislocation creep in response to coseismic rupture. The results suggest that the short-lived thermal pulse generated by the earthquake is sufficient to reset the apatite U-Pb system. The age of 426 ± 19 Ma is interpreted to date lower-crustal seismicity during the early Caledonian orogeny. Later fluid-rock interaction along the same structures led to partial resetting of the apatite U-Pb systematics, indicating that seismic brittle failure of the lower continental crust occurs at the incipient stages of continental collision, and that the resulting structures are preferential pathways for later fluid flow in the otherwise impermeable anhydrous lower crust. [ABSTRACT FROM AUTHOR]

In this study, we use luminescence rock surface dating to provide burial ages for buried surfaces of a large boulder now positioned on top of the ruins of the Neolithic Ba'ja village in Southern Jordan. Luminescence depth profiles for quartz optically stimulated luminescence (OSL), and feldspar infrared stimulated luminescence (IR 50) signals indicate that the boulder experienced a complex transport history of at least two exposure and two burial events before final emplacement. By comparing the fading-corrected feldspar IR luminescence burial ages derived from these rock surfaces with quartz OSL ages derived from sediment infill from the archaeological structures underneath the boulder, it is concluded that there was a rockfall event around 7–8 ka ago, possibly as the result of an earthquake. Whatever the nature of this event, it resulted in the first recorded movement of the boulder, when the rock was presumably dislodged on the hill slope but did not travel all the way to the settlement at the foot of the slope. About 3–4 ka ago, after the village had been abandoned and the rooms filled with rubble, further movement occurred, possibly initiated by an earthquake. This final transport event moved the boulder further downslope, embedding it in the cultural layers of the derelict settlement on top of the partially collapsed settlement walls. [ABSTRACT FROM AUTHOR]

In Central Europe, only a few caves with ancient drawings on the walls are known. During the past years, simple lines and sketches made of charcoal or smearing traces from torches are found mainly in less accessible locations in some caves of the Slovak Karst. Previous attempts to date these findings were unsuccessful since the painted layers were too thin to allow sampling and enable routine AMS dating. Now the application of the small mass radiocarbon accelerator mass-spectrometry (AMS) technique developed at the Australian Nuclear Science and Technology Organisation (ANSTO) made possible successful 14C determinations for a set of cave drawings and markings from the Slovak Karst. This research confirmed the prehistoric/protohistoric nature of the drawings/sketches in Čikova Diera, Silická Ľadnica, Ardovská and Domica Caves. Moreover, this research widens the scope for prehistoric rock art dating, one of the major constrains in rock art studies. [ABSTRACT FROM AUTHOR]

Rock art dating has been one of the major challenges since its discovery and recognition. The methods have evolved through the last century, beginning with the study of superpositions and style until to the application of numeric methods since the 1990s. The aim of this paper is to evaluate and publish an up-to-date database of all of the numerical dates currently available for Iberian prehistoric rock art sites. For this purpose, the manuscript reviews all the methods applied so far to Iberian rock art discussing the limits, the sampling involved, and the problems affecting the results. After that, we present and discuss the most relevant results related to each cultural graphic tradition (Palaeolithic, Levantine, Schematic and Megalithic rock art) assessing their value and limitations. Finally, we reflect on the future of rock art dating: unfortunately most of the motifs are not dateble in numeric terms, meaning we still have to combine traditional with numerical methods; but also, we need to keep working on the problems affecting these methods to be able to create a more reliable chronological framework of use to address other issues such as group mobility, cultural networks, and reutilisation of symbolic elements, to name a few. [ABSTRACT FROM AUTHOR]

New details of chemical structure of Araucaria lignin are the focus of this paper, since Araucaria is a relict plant which fossils are dated by the Permian period. Quantitative chemical analysis, FTIR, EPR and 2D NMR spectroscopies, Py-GC/MS and nitrobenzene oxidation have been used to characterize the Araucaria lignin. This work highlighted the structural features of the lignin of Araucaria , which distinguish it from modern coniferous (gymnosperm) lignins. This lignin exhibits pronounced paramagnetic properties with the concentration of paramagnetic centers of 3.0 × 1017 spin/g, the value of g-factor of 2.0036 corresponds to the phenoxyl radical. The Araucaria lignin is apparently unique since it does not belong to the known G, GS or GSH types. For the first time it was quantitatively proven that he lignin of Araucaria was assigned to compositionally heterogeneous GH lignins, which is not typical for modern lignins. [ABSTRACT FROM AUTHOR]

The study of the Middle Stone Age (MSA) in North Africa is essential to better understand the human dispersals during the Late Pleistocene. The timing of the transition from the MSA to the Later Stone Age (LSA) in the region is still debated due to the scarcity of sites and the limited chronological constraints available. Among the few existing MIS 5 to MIS 1 archaeological sites in Northwestern Africa, El Harhoura 2 cave (Morocco) has been extensively excavated during the last decade. It has provided MSA and LSA sequences from which human remains have been systematically discovered in association with faunal and lithic assemblages. The combined US-ESR method has been applied to date five teeth from layer 3 and 4A, which correspond to the most recent MSA occupations at El Harhoura 2 cave. The results suggest the disappearance of the MSA at this site to have occurred around ∼40 ka, at the end of MIS 3, which is consistent with the palaeoenvironmental interpretation derived from the faunal remains. These new results suggest that the last MSA human occupation are ∼15 ka more recent than previously showed by OSL dating. Further investigation is required to fully understand the reason of such discrepancy between the two methods. [ABSTRACT FROM AUTHOR]

The zircon U-Pb system is one of the most robust geochronometers, but during an impact event individual crystals can be affected differently by the passage of the shock wave and impact generated heat. Unraveling the potentially complex thermal history recorded by zircon crystals that experienced variable levels of shock and heating, as well as additioanl pre- and post-impact thermal events, has been difficult using classical geochronological methods. The existing high-precision 40Ar/39Ar age constraints for the K-Pg Chicxulub event, and the previous U-Pb dating of the basement rocks from the impact site, make Chicxulub an ideal location to study impact-induced effects on the zircon U-Pb systematics and to evaluate potential 'memory effects' of pre-impact U-Pb signatures preserved within those individual zircon crystals. Recent IODP-ICDP drilling of the Chicxulub impact structure recovered 580 m of uplifted shocked granitoid and 130 m of melt and suevite, providing an unprecedented opportunity to study zircon crystals subjected to a range of shock pressures, thermal, and deformational histories. Zircon morphologies were classified using scanning electron microscopy (SEM) imaging and then samples were depth profiled using laser ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS) to document the range of preserved age domains from rim-to-center within individual crystals. The results show U-Pb ages range from 66 to 472 Ma, which are consistent with both inherited Carboniferous and Late Paleozoic basement ages as well as Pb loss ages in response to the K-Pg impact event. While the bulk of the zircon grains preserve Paleozoic ages, high U (metamict) zones within fractured zircon crystals exhibited an age within uncertainty (66 ± 6.2 Ma) of the impact age (66.038 ± 0.049 Ma), indicating that inherited intragrain U-Pb kinetics and/or hydrothermal fluid flow may have controlled age resetting those zircon crystals rather than impact-induced shock and heating alone. Moreover, the calculated α-decay doses suggest that the zircon crystals experienced Stage 1 or early Stage 2 radiation damage accumulation. Therefore, we suggest that the lowered crystal annealing temperature in crystals that previoulsy experienced radiation damage make the zircon U-Pb clock either more susceptible to the relatively short heat pulse of the impact event, the moderate pressure and temperature conditions in the peak ring, and/or to hot-fluid flow in the long-lasting post impact hydrothermal system. • Shocked zircon crystals extracted from Chicxulub's peak ring rocks are analyzed via U-Pb LA-ICP-MS depth profiling. • U-Pb LA-ICP-MS depth profiling and the subsequent data export in 1 s increments allows to spatially resolve age trends. • Zircon U-Pb clock partially and possibly fully reset due to the impact event. • Younger U-Pb ages are preserved in fractured zircon with a high U [ppm] concent. or in zircon displaying granular textures. [ABSTRACT FROM AUTHOR]

This review is a follow up to Grün et al. (2006): Direct Dating of Human Fossils. Since that time there has been progress on the experimental side of the geochronological analyses, which are detailed for uranium-series isotope and ESR dating. Also, many new human fossils, including several new species (e.g., H. naledi, H. luzonensis, and H. longi) have been discovered, named and dated. Direct dating of human fossils has contributed to some major revisions in our understanding of human evolution. For example, the enigmatic Homo floresiensis has been dated to >60 ka instead of ∼18 ka as was originally published. This put an end to the heated debate about how H. floresiensis could have survived the arrival of H. sapiens on Flores for several tens of thousands of years. From Africa, results are presented for Swartkrans, Thomas Quarry, Broken Hill (Kabwe), the Rising Star sites Djebel Irhoud, Florisbad and Omo Kibish. In western Asia, human fossils from Mislya, Tabun, Qafzeh and Al Wusta were analysed and in Europe from Payre, Moula Guercy, Lezetxiki, Apidima, El Sidron and Atapuerca (Sima de los Huesos and Gran Dolina). From Asia and Oceania we discuss the results from Denisova, Penghu, Harbin, Liujiang, Liang Bua, Mata Menge, Callao, Ngandong, Sambungmacan, Wajak, Niah and Tabon, while from Australia WLH50 is added to WLH3. We describe the dating procedures for each site. All published data were re-evaluated. The systematic analysis of the U-series isotopic data led to new insights, particularly with respect to detailed U-diffusion processes (provenance of the uranium, leaching, secondary overprints etc.), which altered the interpretation of the ages for some of the sites. For example, we can show that the minimum age of H. luzonensis is 134 ± 14 ka, covering the transition of MIS6 to MIS 5 (younger dates were the result of secondary U-overprints), and that Apidima 1 and 2 have significantly different isotopic characteristics, refuting claims of initial contemporaneous burials. We discuss the implications of the results for our present understanding of human evolution. • Critical assessment of U-series and ESR dating. • Dating the earliest occurrences of Homo sapiens in Africa, the Levant and Europe. • The ages of new human species found since 2000: H. floresiensis, H. luzonensis, H. nadeli, H. longi. • Updated summary of our present understanding of human evolution. [ABSTRACT FROM AUTHOR]

Rock surface luminescence exposure dating (RSLED) is an evolving tool in dating prehistoric rock surfaces. In this study, we explore and compare current and new models and calibration methods using optically stimulated luminescence (OSL) depth profiles from quartz grains and Infrared Stimulated Luminescence (IRSL; IR 50 , pIRIR 225 , and MET 290) from feldspar grains found in granite and sandstone samples. This study shows that, although correct model assumptions improve the quality of exposure age estimates, significant discrepancies between observed and expected fitting parameter values remain, and these discrepancies leads to inaccurate age estimation. This is particularly the case when post-IR signals from feldspar are used. Here, the spectral dependency of luminescence signals is examined to better understand these problems. The demonstrated depth dependency of fitting parameters, previously assumed to be constant with depth, also gives rise to discrepancies in parameter values. The surprising observation that, in rocks, the IR 50 signal is apparently more easily bleached than the quartz fast-component OSL signal is explained in terms of the wavelength dependence of light attenuation increasing the effective path length for shorter wavelengths, and so changing the shape of the light spectrum with penetration depth. This complicates parameter estimates in exposure dating even more. Alternative approaches (rather than parameter estimation) for estimating how long a rock surface has been exposed to light are considered, based on modelling the shape and position of the measured luminescence-depth profile. It is concluded that the most accurate exposure age is derived by interpolating the depth of an unknown profile onto a curve of profile depths from known age profiles (the Exposure Response Curve, or ERC, approach). • Investigating calibration methods for rock surface luminescence exposure dating. • Rock surface luminescence exposure dating experiments on quartz and feldspar. • Correct model assumptions improve the quality of exposure age estimates. • Discrepancies in exposure age estimations exist using current calibration methods. • The most accurate exposure age is derived by interpolation of bleaching depth (ERC). [ABSTRACT FROM AUTHOR]

The Bangong–Nujiang suture zone (BNSZ) is the remnants of the Meso-Tethyan main oceanic basin in the Tibetan plateau. It is noted that several microcontinents, e.g., Amdo and Jiayuqiao, occur within the Meso-Tethyan ocean basin. These microcontinents were strongly reworked associated with the subduction and closure of this ancient ocean, thus they play a key role in understanding the evolution of this ocean. In this contribution, we report newly documented Early Jurassic gabbros (ca. 182–175 Ma) from the Amdo microcontinent in the middle segment of the BNSZ. The gabbros can be subdivided into two groups, i.e., OIB (ocean island basalt) and MORB (mid-ocean ridge basalt) groups. The OIB-group gabbros are characterized by highly enriched Nd Hf isotopic characteristics (zircon ε Hf (t) = −11.7 to −8.9; whole-rock ε Nd (t) = −11.0 to −10.1). They are geochemically similar to OIB and are interpreted to be products of the partial melting of a relatively deep mantle source (> 85 km) and subsequent continental crustal inputting. The MORB-group gabbros belong to the tholeiitic series and have similar compositions to those of MORB. They were most likely derived from a depleted mantle source (zircon ε Hf (t) = +3.7 to +16.5; whole-rock ε Nd (t) = +4.9 to +8.1) in a relatively shallow depth (< 85 km). Integrating previous studies with the data presented in this contribution, we suggest that the generation of coeval OIB- and MORB-like gabbros are related to lithospheric delamination after the Qiangtang-Amdo collision and the closure of the Bangong-Nujiang ocean basin. This result will give new constraint on the evolution of the Meso-Tethyan Ocean. • Early Jurassic gabbroic dikes were newly documented in the Amdo microcontinent, central Tibet. • Gabbroic rocks display different geochemical compositions with OIB and MORB features. • Zircon U-Pb dating on gabbroic rocks yielded nearly uniformed ages of 182–175 Ma. • Gabbroic rocks were formed by the lithospheric delamination after the Qiangtang-Amdo collision. [ABSTRACT FROM AUTHOR]

Mafic rocks are the most common type of igneous rocks on Earth, however, constraining the crystallization age of mafic rocks can be challenging. Apatite is a common accessory phase in mafic rocks and is amenable to dating using the U–Pb system. However, the U–Pb system in apatite has a relatively low closure temperature (∼350°-550 °C) and is therefore prone to resetting by later thermal and metasomatic events. Here, a recently developed Lu Hf dating method using laser ablation reaction-cell mass spectrometry is applied to apatite from mafic rocks. The Lu Hf system in apatite has a higher closure temperature (∼650°-750 °C) compared to U–Pb, increasing the chances of obtaining primary crystallization ages. Furthermore, the laser-ablation method allows rapid data collection compared to traditional solution-based Lu Hf dating techniques. Four study areas were selected to compare the Lu Hf vs U–Pb systematics of apatite in mafic igneous rocks: the Paleoproterozoic Sudbury Igneous Complex (Canada), the Neoproterozoic Borborema Province (NE Brazil), the Paleoproterozoic Fennoscandian Shield (Finland), the Archean Yilgarn Craton and adjacent Mesoproterozoic Albany Fraser Orogen (Western Australia). For all analyzed samples that have apatite trace element compositions typical of an undisturbed primary mafic igneous lithology, the Lu Hf system retains primary igneous apatite crystallization ages, whereas the U–Pb system in the same grains often records isotopic disturbance or a cooling age. In few cases, the Lu Hf system has also been disturbed in response to recrystallization, however, such disturbance is readily detected with trace element data. Hence, this study demonstrates the potential of laser ablation apatite Lu Hf dating to obtain primary crystallization ages for otherwise difficult to date mafic rocks. • First study on Lu-Hf systematics for apatite from mafic rocks • U U-Pb system in apatite readily resets by thermal and metasomatic events • Lu Lu-Hf system is robust to volume diffusion < ∼660–730 °C, retaining primary crystallization ages. • Deformation leading to recrystallization 'resets' both U U-Pb and Lu Lu-Hf systems in apatite. • Apatite trace element data to differentiate isotopic disturbances related to recrystallisation versus volume diffusion [ABSTRACT FROM AUTHOR]

Detrital zircons in modern stream sands and terraces of the Snake River drainage upstream of and within Hells Canyon, western Idaho, U.S.A, effectively reproduce the geochronometry of Idaho magmatic rocks, both from Laurentia in eastern Idaho, and from the accreted terranes west of the Salmon River Suture. We used large-n (300 grain) analysis of detrital zircon ages and Monte Carlo-based mixture modeling to estimate the percent contributions from the upper Snake River and several tributaries. The large number of grains analyzed allows more precise statistical modeling than previous studies, which used 60 or 100 grains. Immediately upstream of the Hells Canyon Complex of dams modeling suggests that the Snake River at Farewell Bend contains detrital zircon contributions of Payette River 50 % and Boise River 10 % (mainly from the Atlanta lobe, Idaho batholith). The upper Snake River has 30 % contribution and contains a complex detrital zircon signature including both primary zircons derived from magmatic sources and recycled zircons derived from sedimentary rocks with an ultimate magmatic source. Thus, 60 % of the detrital zircons come from the 98–73 Ma southern Idaho batholith, with less than a third coming from the upper Snake River drainage, despite it representing 60 % of the drainage area. The Owyhee, Malheur, and Weiser rivers contribute <5 % each. Within Hells Canyon, modeling suggests that the main Snake River contributes by far the largest component (85 %); side canyons contribute <5 % of the zircon load. Mixing models for Snake River stream sediment downstream of Lewiston, below Lower Granite Dam (sampled from sands deposited before installation of the dam), suggest 53 % contribution from the main Snake River above the Salmon River, 34 % from the Clearwater River, 7 % from the Salmon River, and 6 % from the Grande Ronde River. Comparing relative zircon inputs from the modern Snake and Salmon rivers to a pre-dam river terrace just downstream from their confluence suggests that the Snake River in Hells Canyon today contributes only 4 % of the detrital zircons whereas before installation of the Hells Canyon Dams it contributed 29 %. We interpret this reduction in detrital zircon supply to be caused by sediment trapping above the dams. One influence on the detrital zircon contribution of various streams is peak flow volume. Zircon fertility of specific source rocks is the main influence on detrital zircon percentages within individual drainages. Mesoproterozoic, Cretaceous and Eocene granitic rocks produce euhedral magmatic detrital zircon grains that dominate several drainages. Mesozoic metavolcanic and Eocene Challis Volcanic Group rocks yield fewer and often broken detrital zircon grains. Large outcrop areas of Neogene Columbia River and Snake River Plain basalts provide almost none. Recycling of older magmatic detrital zircon through Proterozoic and Paleozoic sandstones is a signature of the eastern and central Idaho thrust belt. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ediacaran-Cambrian series of Cap de Creus studied through Nd isotopic sources. • Eastern Pyrenees series (Cap de Creus) show Nd model ages ranging 1.4–1.6 Ga. • Coeval series from different Iberian terranes show contrasted Nd isotopic sources. • These data suggest different original locations along the Gondwana margin. • Isotopic tracers are a useful tool to check the provenance in paleoreconstructions. The North African margin of Gondwana formed by subduction and accretion during Ediacaran to Cambrian times. Sections of this active margin were incorporated during the late Paleozoic to the Variscan and Appalachian orogens. In the Variscan realm, these sections define in some regions a Cadomian basement comprising thick metasedimentary series associated with coeval subduction-related magmatic rock dated in the range 650–500 Ma. In the Cap de Creus Massif (Eastern Pyrenean domain), the Cadomian metasedimentary rocks formed from sediments derived from mixed felsic and intermediate/mafic sources, intruded by granitoid and minor mafic igneous rocks. These series were formed in a peri -Gondwanan volcanic arc setting, like other Cadomian series described in the SW of the Iberian Massif, such as Serie Negra Group of the Ossa Morena Complex. However, the Nd model ages of the Cap de Creus metasedimentary samples range from 1431 to 1620 Ma and are younger than those of their SW Iberia equivalents. This result can be interpreted as an indication of an eastern location in the Ediacaran - Cambrian peri -Gondwanan magmatic arc. Furthermore, the Cadomian series in the Central Iberian Zone have even younger Nd model ages than those of SW and NE Iberia. We present two end-member paleogeographic models consistent with reconstruction of the initial location of the Cap de Creus Massif and its relations with other domains (Ossa Morena Complex and Central Iberian Zone) in this sector of the North African Gondwanan margin. [ABSTRACT FROM AUTHOR]

In the Precambrian dolomites in the central Sichuan Basin, a substantial paleo-oil system previously existed, which has since evolved into a dry gas system that is currently in place. The genesis of this paleo-oil system remained poorly understood, leaving uncertainties regarding the timing of oil charging and associated source rocks. Integration of Re–Os geochronometry with basin modeling allows temporal-spatial constraints on the ancient petroleum system to be established. Two texturally distinct generations of reservoir bitumen were identified. Late-generation bitumen yielded a geologically meaningful Re–Os age of 189 ± 20 Ma (MSWD = 10.4, 2σ), distinct from the previously documented Re–Os ages such as the 414 ± 44 Ma reported by Shi et al. (2020). This new age, along with the ∼414 Ma, aligns within uncertainties with the two relative timings derived from our independent basin model (ca. 450–390 Ma and 260–180 Ma), revealing two temporally distinct oil generation-migration events. The date of ∼189 Ma also lends support to the previous oil charge timing inferred from fluid inclusions. We evaluated the imprecisions of these two Re–Os ages and considered them to result from a narrow spread in 187Re/188Os, and variations in initial Os isotopic compositions (Os i) due to the giant size of the petroleum system and a long duration of oil generation from source kitchen over a large geographical area in this play. Effects of asphaltene precipitation, due to uplift-induced decompression of the migrating oils, may also have contributed to the scatter. Separating the samples based on Os i produced a higher precision age (184.1 ± 5.7 Ma, Model 1) with an MSWD of 0.97. The first oil charge is relatively weak as shown by the basin model and observed bitumen volumes, and it had not been well preserved due to significant reservoir exhumation by Caledonian tectonism. Consequently, the younger oil charge is considered to be the principal precursor to the current dry gas accumulations. Os isotope histories for four potential source units were constructed using publicly available Re–Os data. Comparisons between bitumen and rock Os compositions tend to support the lower Cambrian Qiongzhusi Formation as the predominant source unit for the two major paleo-oil charges. However, contributions from the Duoshantuo, Dengying, and Maidiping source rocks can not be precluded. Overall, these new observations allow temporal-spatial constraints to be placed on the complex evolution, from paleo-oil generation to destruction and dry gas generation. • Two paleo oil charges sourced from the lower Cambrian Qiongzhusi shales. • Agreement between two bitumen Re–Os ages and modeled oil generation stages. • Assessing the precision limitations of hydrocarbon Re–Os ages. [ABSTRACT FROM AUTHOR]

Alkaline rocks of prevailing sodic composition form major ring complexes and stocks along a seismically active N–S structural lineament parallel to the Paraguay river course. All these occurrences are encompassed by the Alto Paraguay Province, their rocks corresponding to the oldest known alkaline magmatic activity in the Paraná Basin, with a Middle Triassic age of 241.5 ± 1.3 Ma. Intrusive rocks ranging from silica-undersaturated (nepheline and/or sodalite syenites) to silica-oversaturated (quartz syenites and alkali granites) and their fine-grained counterparts constitute the most abundant rock-types. Clinopyroxenes, associated amphiboles and varying amounts of biotite are the main mafic minerals present. Alkali feldspar (mainly mesoperthites and subordinate sanidine and anorthoclase) and feldspathoids (nepheline and/or sodalite) are widespread. A late-stage magmatic to metasomatic/deuteric mineral assemblage is mostly typical of miaskitic to agpaitic rocks of the Cerro Boggiani complex, whereas rare accessory silicate minerals are found in peralkaline syenites of the Cerro Siete Cabezas major intrusion. Positive Nb–Ta and Zr–Hf anomalies and negative Sr, P, and Ti spikes are common features to the whole province. REE behavior shows enrichment in LREE and strong LREE/HREE fractionation with various parallel subtrends. This paper addresses petrological aspects of the origin and evolution of these alkaline rocks. • The paper reviews knowledge about the Alto Paraguay Alkaline Province (border between Brazil and Paraguay). • The main rock types vary from undersaturated (nepheline and sodalite syenites) to silica-oversaturated (quartz syenites and alkali granites) and their fine-grained equivalents. • The intrusion of the alkaline bodies took place along an N–S-oriented structure that marks the boundary of the Pampia and Rio Apa cratonic blocks. • The rocks are dated from the Middle Triassic and constitute the oldest alkaline magmatic event on the edge of the Paraná Basin. [ABSTRACT FROM AUTHOR]

In this work, we report the geochemical, whole-rock Sr-, Nd-, and Hf-isotopes, and zircon U–Pb age and Hf–O isotopic compositions for six granitic intrusions in northeastern Fujian, coastal region of southeastern China, to elucidate the petrogenesis of aluminous and peralkaline A-type granites in this region. Zircon U–Pb dating of these rocks (including porphyritic syenites, porphyritic granites, alkali-feldspar granites, and arfvedsonite granites) yielded Late Cretaceous ages of 94–98 Ma. Mineral assemblage and geochemical features suggested that the arfvedsonite granites were peralkaline A-type but the porphyritic syenites, porphyritic granites, and alkali-feldspar granites were aluminous A-type. Geochemical data, whole-rock Nd–Hf isotopes (ε Nd (t) = −5.5 to −4.0, ε Hf (t) = −3.6 to 0), and the zircon Hf–O isotopes (ε Hf (t) = −3.0 to +1.4, δ18O = 5.4‰–6.0‰) indicated that the porphyritic syenites were produced by partial melting of crustal rocks in the lower crust. The porphyritic granites and alkali-feldspar granites had similar geochemical features and zircon Hf–O isotopic composition with the porphyritic syenites, suggesting that they were formed by feldspar-dominant crystal fractionation of deep crust derived syenitic magma under shallow crustal level. Compared with the aluminous A-type granites, the peralkaline A-type granites had lower abundance of Al 2 O 3 , MgO, CaO, Ba, and Sr, higher abundance of SiO 2 and HFSE, as well as higher ratio of total FeO/MgO, Ga/Al, and Rb/Sr. However, the whole-rock Nd-, Hf- and zircon Hf–O isotopic compositions of the peralkaline and aluminous A-type granites were similar. It could be inferred that the peralkaline A-type granites were formed by crystal fractionation of aluminous A-type granitic magmas. Since the studied A-type granitic intrusions were coeval with the bimodal volcanic rocks and the extensional basins in the coastal region of southeastern China, they were likely produced in an extensional setting, possibly during lithospheric thinning that resulted from the subduction of the paleo-Pacific plate beneath southeastern China. • Aluminous and peralkaline A-type granites were crystallized at 94–98 Ma. • Aluminous and peralkaline A-type granites were derived from a common source. • Aluminous A-type granite was produced by partial melting of lower crustal rocks. • Peralkaline A-type granite was formed via crystal fractionation. [ABSTRACT FROM AUTHOR]

• A continuum of Paleoproterozoic heritage, seen in Nd model ages, from N to S in the Bushmanland Domain (BD), with the Buffels River shear zone simply a regional discontinuity. • The southern BD (SBD) has a greater juvenile component than the northern BD (NBD), becoming more dominant post-1.10 Ga. • Orthogneisses derived from crustal magmas with subduction-influenced signatures with mixed Meso- to Paleoproterozoic model ages. The SBD Koperberg Suite derived from low degrees of melting of enriched SCLM, but at deeper levels than those of the NBD. • The paragneisses derived from largely reworked, mixed Meso- to Paleoproterozoic felsic to intermediate sources. • Paragneisses derived from largely reworked, mixed Meso- to Paleoproterozoic felsic to intermediate sources. • SBD Koperberg Suite derived from low degrees of melting of enriched SCLM, but at somewhat deeper levels than NBD Koperberg magmas. • D 2 deformation constrained to ~ 1.11-1.09 Ga, with peak M 3 metamorphism at ~ 1.05-1.02 Ga. The timing of tectonomagmatic events and petrogenesis of ortho- and paragneisses within the high-grade southern Bushmanland Domain (SBD) of the Namaqua Metamorphic Province is, largely, poorly constrained. U-Pb age dating and whole rock lithogeochemistry of the rocks of the upper granulite facies Kliprand dome provide constraints with regards to the evolution of the SBD during the 1.2–1.0 Ga Namaquan Orogeny. The SBD has a greater juvenile component, particularly added between ∼1.1 and 1.02 Ga, compared to the northern Bushmanland Domain (NBD). This is reflected in marginally younger T DM model ages (1.60–1.95 Ga) than for the NBD (∼1.9–2.4 Ga), and higher ε Nd(t) values for magmatic rocks, particularly for the late- to post-tectonic Spektakel Suite (SS), concentrated in the SBD. The ∼1.06 Ga Klein Lieslap Charnockite of the SS was derived from reworking of radiogenic Paleoproterozoic arc crust, but has a large juvenile depleted component compared to that of the ∼1.19 Ga Grootberg Gneiss of the syn-tectonic Little Namaqualand Suite. SBD mafic magmas were derived from low degrees of partial melting of subduction-influenced enriched subcontinental lithospheric mantle. The pre-tectonic ∼1.17 Ga Oorkraal Suite shows limited crustal contamination of mantle-derived melts. The post-tectonic ∼1.05 Ga Koperberg Suite was derived from deeper mantle melting than that in the NBD, but shows less crustal contamination. The supracrustal Kamiesberg Group was derived from mixed, reworked Meso- to Paleoproterozoic crust that showed a more dominant depleted component compared to that in the NBD. Incongruent anatexis of the paragneisses gave rise to crosscutting garnetiferous quartzofeldspathic segregations, notably the strongly peraluminous ∼1.07 Ga Ibequas Leucogranite. D 2 deformation, at ∼1.11–1.09 Ga, resulted in penetrative foliation. D 3 deformation, related to the development of a sub-vertical foliation in the limbs of F 2 folds, is constrained to ∼1.07–1.06 Ga, between emplacement of the Ibequas Leucogranite and the Koperberg Suite. Peak granulite facies M 3 metamorphism occurred at ∼1.05–1.02 Ga. These age constraints are similar to those of the NBD reflecting a synchronous tectonomagmatic and kinematic history. The SBD represents a deeper crustal level with a greater mantle influence than the NBD. [ABSTRACT FROM AUTHOR]

Extensive Mesozoic outcrops exposed in the Aaiun-Tarfaya Basin, in the Atlantic margin of Morocco, have been overlooked for decades. Original subdivisions and dating of rocks, performed more than five decades ago, have survived until today virtually without any update. In the north eastern margin of the basin, key Mesozoic sections have been revisited. Its coastal position next to the Variscan Anti-Atlas Orogen allows insight into the interplay between local tectonics and eustasy during deposition of sedimentary sequences on passive margins. High-resolution stratigraphy and sedimentology have allowed for an improved understanding of the depositional systems and evolution during the early opening of the Atlantic and provided a valuable control point recording the syn - and early post-rift evolution of the basin. Three formations are described: (i) a basal continental red bed unit unconformably overlying the Palaezoic Variscan basement of the Ifni Inlier; (ii) a unit dominated by intertidal clastics and microbial carbonates, and (iii) a shallow marine unit comprising mixed siliciclastic-carbonates. Despite the sedimentological affinity of these outcrops to Triassic or Lower Jurassic deposits elsewhere in Morocco, these units had previously been assigned an Early Cretaceous age, based on limited non-conclusive fossil fauna and basin-scale lithostratigraphic correlation. New collections of macrofauna have yielded a Bathonian age for the upper part of the succession and a possible Triassic/Early Jurassic for the lower part. The whole succession displays an overall transgressive trend not consistent with the eustatic Bathonian sea-level fall. Local post-rift tectonic pulses exhuming the Western Anti-Atlas coupled with eustasy are responsible for increased sediment supply at this time. Enhanced tectonic subsidence, overcoming sea-level fall, is interpreted to be the main driver for creation of accommodation and preservation of this sequence. Resumed sedimentation on structural heights offshore suggests exhumation of the Western Anti-Atlas ceased by the early Callovian, reducing clastic input to the region and allowing the development of a carbonate platform. Variable regional exhumation and local tectonics along the Moroccan margin during the early post-rift stage influenced the highly variable nature of clastic vs carbonate deposition, thickness distribution and depositional environments at this time. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Zircon U–Pb dating indicates the emplacement of Ruocuo adakitic porphyries during the Early–Middle Jurassic (182–170 Ma). • Ruocuo adakitic porphyries were generated by the partial melting of the Neo-Tethys oceanic slab. • Formation of Early Mesozoic magmatic rocks in the southern Lhasa subterrane in a magmatic arc setting. • The northern Xigaze forearc basin has a potential for subduction-related porphyry Cu–Au mineralization. Abstract Jurassic adakitic rocks in the southern Lhasa subterrane are relatively rare, poorly documented, and their petrogenesis and geodynamic setting are unclear. To explore these issues, we present zircon U–Pb ages along with Hf isotopic, whole-rock geochemical, and Sr–Nd–Pb isotopic data for hornblende quartz diorite porphyry (HQDP) and quartz diorite porphyry (QDP) in the Ruocuo area, southern margin of the Lhasa terrane, Tibet. Zircon U–Pb dating for these rocks indicates that they were emplaced in the Early–Middle Jurassic (182–170 Ma). Geochemically, HQDP and QDP both show characteristics of adakites, with intermediate SiO 2 (60.62–65.63 wt% and 57.46–60.04 wt%, respectively), relatively high Al 2 O 3 (14.23–18.23 wt% and 18.32–20.14 wt%, respectively) and Sr (344–571 ppm and 514–614 ppm, respectively), and low Y (9.12–13.0 ppm and 11.0–14.9 ppm, respectively) and Yb (0.93–1.31 ppm and 1.08–1.52 ppm, respectively). In addition, they show relatively low ratios of (87Sr/86Sr) i (0.7038–0.7045), (206Pb/204Pb) i (18.31–18.42), (207Pb/204Pb) i (15.56–15.66), and (208Pb/204Pb) i (38.36–38.77) and relatively high values of ε Nd (t) (+5.54 to +6.33) and ε Hf (t) (+11.8 to +17.3). The Sr–Nd–Pb–Hf isotopes of HQDP and QDP are similar to those of the Yarlung Tsangpo ophiolites, indicating that they were predominantly generated by the partial melting of the subducted Neo-Tethys oceanic slab. The subducted Neo-Tethys oceanic slab-derived adakitic rocks that are present in the southern Lhasa subterrane provide strong evidence for proving the presence of oceanic subduction during the Early–Middle Jurassic. By combining our results with the previously reported results, we suggest that the Ruocuo adakitic rocks and Early Mesozoic (Late Triassic to Middle Jurassic) magmatic rocks in the southern Lhasa subterrane formed in a magmatic arc setting related to the northward subduction of the Neo-Tethys oceanic slab, that the initial subduction of the Neo-Tethys oceanic slab occurred prior to the Early Jurassic, and that the upwelling asthenosphere, triggered by the roll-back of the subducted Neo-Tethys oceanic slab, provided the heat that was required for slab melting. However, contrasting these results with the geochemical characteristics of the No. 2 deposit in the Xiongcun Cu–Au district leads us to consider that the Early–Middle Jurassic subducted oceanic slab-derived adakitic porphyries contain a greater potential for porphyry Cu–Au mineralization than the Early Mesozoic normal magmatic rocks in the southern Lhasa subterrane. Furthermore, mineralized Jurassic porphyry has been reported in the Ruocuo area, adjacent to the northern Xigaze forearc basin, indicating that the northern Xigaze forearc basin also has the potential for subduction-related porphyry Cu–Au mineralization. [ABSTRACT FROM AUTHOR]

Abstract The provenance of sediments in western Taiwan has been the subject of debate in recent years. Previous investigators, solely based on the U-Pb zircon geochronology for the detrital grains, all advocated the important roles, but with varying emphasis, of drainage systems in the South China Block. Influence of the Changjiang (Yangtze) River from the far-source Yangtze block versus nearby systems like Zhujiang, Minjiang and Jiulongjiang Rivers in the Cathaysia block has been the main issue. However, the fundamental question of whether the provenance is really the South China Block has never been evaluated. Here we report both the U-Pb zircon and Electron MicroProbe (EMP) monazite age data for seven sediment samples from two sides of the Taiwan Strait and synthesize the published data for all these rivers and sedimentary strata in western Taiwan to tackle this problem. The lack of, or insufficient, ~1.8 Ga monazites in the sediments of river mouths for all drainage systems in the South China Block makes them unlikely to be the source of Miocene sediments in western Taiwan where ~1.8 Ga monazite grains occupy 14.5–33.3% of the total age population. With reference to the tectonic evolution of the coastal southeast China-Taiwan region during Early Cretaceous to recent time, we propose a new explanation that invokes a now-concealed microcontinent along the Manila Trench. This microcontinent, probably related to a Paleoproterozoic orogen in Gondwana, eventually collided with the South China Block causing uplift of the easternmost structural element—the Pingtan-Dongshan Metamorphic Belt (PDMB) at ca. 130–120 Ma. It then drifted away sometime after 100 Ma and split into two parts with one becoming today's Palawan-Mindoro terrain of the Philippines. As indicated by the geophysical data near southern Taiwan, the remainder of this split microcontinent had subducted underneath the Philippine Sea plate along Manila Trench as a result of the opening of the South China Sea at ~33 Ma. Both the Peikang and Kuanyin basement highs in the offshore western Taiwan represent the unsubducted remnants of this microcontinent and also the major suppliers of Late Oligocene-Miocene sediments in western Taiwan. On the other hand, the Eocene-Early Oligocene strata of the Hsuehshan Range in central Taiwan show both zircon and monazite age patterns resembling the Eocene-Early Oligocene and recent sediments of the Zhujiang drainage system, indicating the southwestern origin of the protolith Taiwan. This scenario also matches the recent proposition that part of the Central Range belongs to the deep-level accretionary prism of a Miocene subduction system. Highlights • Disputes over the provenance of western Taiwan sediments are reassessed using EMP monazite ages. • Drainage systems in the South China Block are unlikely the major contributors. • A now-concealed microcontinent related to a Paleoproterozoic orogen is the alternative. • Protolith Taiwan was originated from South China carrying pre-Miocene Zhujiang sediments. • Younger sediments were derived from this microcontinent with adjacent basement highs as remnants. [ABSTRACT FROM AUTHOR]

Abstract The Re-Os geochronometer can be applied to date petroleum, which is the end product of complex natural processes. Improved interpretation of natural Re-Os datasets requires identification of key controlling factors for Re-Os systematics and their isotopic imprint in oils. Here, we focus on the role of water in (re)setting the Re-Os geochronometer in oils, as formation waters and oils often coexist in basinal systems. To quantify Re-Os systematics during water-oil interaction, we performed a series of equilibration experiments between different oils and dilute aqueous solutions doped with Re and Os. The investigated parameters include the oil composition, water to oil ratio, interaction time and the initial Re-Os content in the aqueous solution. In experiments performed across a high concentration gradient, the oils fully homogenized with respect to their Os isotopic composition but had variable 187Re/188Os ratios. This indicates that the Re-Os geochronometer has been reset during water-oil interaction. However, in experiments investigating partial isotopic overprint, the crude oil and its maltene and asphaltene fractions preserved their isochron-derived age. Thus, the Re-Os radiometric clock of a single crude oil sample remains intact, even during partial equilibration of the 187Os/188Os ratio. These experimental findings provide a new foundation for interpretation of Re-Os systematics in natural water-hydrocarbon systems. [ABSTRACT FROM AUTHOR]

Abstract Large Igneous Provinces mark important and consequential events that span almost the entirety of the Earth's history. These punctuated geologically significant events that include earth processes from the core to the atmosphere have been linked to climate changes, mass extinctions, and even large-scale tectonic shifts. To begin to understand the role LIPs play in these important moments across Earth's lifespan, a thorough understanding of how they form in the first place is imperative. The ∼180 Ma Karoo Continental Flood Basalt (CFB) Province has been heavily studied with one of the largest geochemical and geochronological databases available for a CFB; providing an excellent avenue to study in detail the petrogenesis of these large collections of magma. However, despite this large dataset, the origin of the Karoo CFBs is still debated, with many different and conflicting models proposed. Disparities in these models can often be traced down to the degree of influence a plume and/or the sub-continental lithospheric mantle (SCLM) had during the genesis of this magmatic province. Nine sills intruded into the Western Cape Province of the Karoo Basin were investigated using 40Ar/39Ar geochronology, whole rock geochemistry, and Sr, Nd, Pb isotopes. Five of these sills are peculiar as they contain hydrated minerals (biotite and hornblende), an unusual feature for Karoo basaltic rocks. Biotite and/or hornblende separates yielded statistically indistinguishable 40Ar/39Ar ages as plagioclase separates; indicating that the biotite and hornblende found within these samples are primary features requiring that water was present in the magma during the crystallization of those sills. Major and trace element geochemistry place these rocks into the low-Ti suite of the Karoo CFBs. Trace elements indicate the involvement of fluids over sediment within the source region for these Karoo magmas. All samples from the Western Cape Province display enriched Sr–Nd–Pb initial values with large variations in elemental concentrations for a restricted range of isotopic ratios. Assimilation models indicate these enriched isotopic contents and observed trends are not the result of crustal contamination and are representative of the composition of the source. The trace element and isotopic geochemistry as well as the primary hydrated minerals indicate that water present in the system at the time of formation came directly from one of the mantle sources, supporting the hypothesis that the SCLM was metasomatized by fluids plausibly as a result of the Proterozoic Kibaran Orogeny and/or the Permian Cape Orogeny. This first direct evidence of water within the mantle sources of tholeiitic CFBs, until now only theorized and modeled, potentially changes the fundamentals in how we approach our considerations of CFB generation as a whole. Highlights • Primary hydrous minerals provide first evidence of hydrated material within the Karoo magmas. • The major, trace, and isotopic geochemistry of these hydrous dolerites indicate a hydrated source for the Karoo magmas. • These results support the hypothesis that the SCLM was metasomatized by fluids from ancient subduction. [ABSTRACT FROM AUTHOR]

The oldest rocks of the Rio Negro Province in the Amazonian Craton, have a complex evolutionary history and little known about them. In this paper are presented field, microtextural data, amphibole and plagioclase mineral chemistry, zircon U–Pb ages, and Sm–Nd isotope composition from Içana Domain basement rocks which belong to the Rio Negro Province. The studied area of the province is located in the extreme northwestern portion of Brazil (Amazonas State). The integration of the data obtained in this study allowed to propose the tectono-metamorphic evolution of Içana Domain in the Rio Negro Province. The basement rocks comprise orthogneiss and metagranite of the Cauaburi Complex and homogeneous/heterogeneous diatexite of the Taiuaçu–Cauera diatexite. The Cauaburi Complex rocks exhibit a predominantly porphyroclastic texture and has a mafic mineralogy constituted by biotite, amphibole, sphene, epidote, and allanite. On the other hand, Taiuaçu–Cauera diatexite varies from inequigranular to porphyroclastic, being constituted by biotite, muscovite, allanite, and epidote. Basement rocks of the Içana Domain record three tectonic–metamorphic events, which were associated to regional events. The M 1 /D 1 event was marked by the syn-tectonic emplacement of the Cauaburi Complex protolith rocks (1813 ± 19 Ma), and also by crystallization (1821 ± 14 Ma) and migmatization (1788 ± 11 Ma) of the Taiuaçu-Cauera diatexites in an orogenic event. The M 2 /D 2 event reached high temperatures, similar to the M 1 /D 1 event and was related to emplacement of S–type granites in the Içana Domain basement during the Içana Orogeny (ca. 1520 Ma). Furthermore, the lower temperature of the M 3 /D 3 event was related to intracontinental reworking of the K'Mudku event (ca. 1200 Ma). The Cauaburi Complex basement rocks shows epsilon Nd (t) values range from +1.53 to +0.13, which allow the identification of a crustal contribution to the magma source (likely Orosirian sialic crust). Geochemistry data indicate that these rocks have been generated from partial melting of amphibolitic rocks, and also with an important crustal component related to magmatic arc settings. All igneous (1967 ± 25 Ma) and metamorphic (1911 ± 15 Ma) zircons grains within the Cauaburi Complex basement rocks are compatible with those found in Tapajós-Parima/Ventuari–Tapajós Province, reinforcing the crustal contribution hypothesis. Geochemistry and mineralogical data indicate that Taiuaçu-Cauera diatexite was likely formed by the partial melting of the metagraywacke. Two age populations (1993 ± 33 and 1842 ± 9 Ma) from detrital zircon of the homogeneous diatexite, suggest that the sediments were derived from different rocks of the Tapajós-Parima/Ventuari–Tapajós Province. The age of the Taiuaçu-Cauera diatexite is probably between 1842 ± 9 Ma (youngest detrital zircon) and 1788 ± 11 Ma (anatectic zircon). The youngest detrital zircon (1842 ± 9 Ma) and anatectic zircons (1788 ± 11 Ma), indicates that the protolith of Taiuaçu-Cauera diatexite is not a part of the Tunuí basin (Tunuí Group). [ABSTRACT FROM AUTHOR]

The Sierra Nevada de Santa Marta in NW Colombia is an isolated massif at the northernmost end of the Andes chain near the boundary with the Caribbean plate. Previous geologic mapping and K-Ar dating have shown that Jurassic plutonic and volcanic units make up a large part of the Santa Marta Massif (SMM). These rocks have been considered to be part of a Jurassic magmatic arc extending from NW Colombia to northern Chile, but without any geochemical basis for comparison. This paper reports on a geochemical and Sr-Nd-Pb isotope study of the Jurassic rocks in the SMM and provides 12 new U-Pb zircon ages from in-situ laser ICP-MS dating. The plutonic and volcanic units span a range from 45 to 78 wt.% SiO 2 , with a dominance of intermediate to felsic compositions with SiO 2 > 57 wt.%. They classify as calc-alkaline, medium to high-K, metaluminous rocks with trace-element features typical for arc-derived magma series. In terms of their major and trace-element compositions, the SMM Jurassic units overlap with contemporary plutonic and volcanic rocks from other regions of the Central and Eastern Cordilleras of Colombia, and confirm an arc affinity. The new U-Pb ages range from 176 ± 1 Ma to 192 ± 2 Ma (n = 12), with most between 180 and 188 Ma (n = 7). The initial Sr isotope ratios (at 180 Ma) are between 0.7012 and 0.7071 (n = 29), with 3 outliers attributed to mobilization of Rb and/or Sr. Nearly all samples have negative εNd (180) values between −10.3 and 0.0 (n = 30), the two exceptions being only slightly positive (1.1 and 1.9). Measured Pb isotope ratios fall in a narrow range, with 206 Pb/ 204 Pb from 18.02 to 19.95, 207 Pb/ 204 Pb from 15.56 to 15.67 and 208 Pb/ 204 Pb from 37.76 to 39.04 (n = 28). In the regional context of previous studies, these results confirm early Jurassic ages and an arc affinity for the widespread magmatism exposed in the eastern and northeastern Colombian Andes. We also note patterns in the distribution and composition of magmas. The magmatic activity in the Central Cordillera tends to be younger than in the Eastern Cordillera and is spatially more restricted to the vicinity of regional fault systems. In terms of composition, Jurassic igneous rocks in the Eastern Cordillera have systematically lower εNd (180) values than those from the Central Cordillera, whereas the Pb isotope ratios overlap. We ascribe the Nd isotope variations to heterogeneity in the mantle source and/or degree of crustal contamination, whereas the Pb isotope ratios are crust-dominated and similar throughout the region. The spatio-temporal and compositional evolution of Jurassic magmatic rocks in the Northern Andes reflect the major plate kinematic readjustment between the Triassic and the Early Jurassic in the proto-Andean margin. [ABSTRACT FROM AUTHOR]

The Borborema Province is an important Precambrian orogenic system in Northeastern Brazil. It was formed during the assembly of Western Gondwana in the Brasiliano-Pan-African Orogeny. The Neoproterozoic Sergipano Belt is part of the Province and occupies a large area of its southern portion. Investigation of provenance and tectonic environment of the metavolcanic-sedimentary complexes in this belt are of regional amplitude and may reveal important aspects of the evolution of the province. In this study new whole-rock geochemistry, isotope Nd data and U-Pb geochronological data on detrital zircon of the metavolcanic-sedimentary Araticum Complex within the northeastern part of the Sergipano Belt, in order to contribute to the understanding the role of the Sergipano Belt in amalgamation of Western Gondwana. The related data indicate provenance from eroded island arcs and back-arc-relate settings during the Neoproterozoic. Detrital zircon grains indicate populations of Ediacaran-Cryogenian (ca. 660-620 Ma) and Tonian-Stenian ages (around ca. 1047 Ma) suggesting that source areas represent extinct volcanic arcs of the Pernambuco-Alagoas Domain to the north. Based on this study, it is suggested that sediments of the Araticum paleobasin were deposited in an oceanic environment during the arc exhumation over the Brasiliano-Pan African Orogeny, but also with strong contributions from Stenian island arcs, which are attributed to the Cariris Velhos Orogeny. Our results support that major supracrustal sequences of the Sergipano Fold Belt were deposited in the Neoproterozoic, such as indicated by previous studies. [ABSTRACT FROM AUTHOR]

Abstract Apatite is an accessory mineral that is frequently found in both igneous and clastic sedimentary rocks. It is conventionally considered to be characterized by a closure temperature range between 375 and 600 °C and hence has been employed to address mid-temperature thermochronology questions relevant to the reconstruction of thermal events in the middle to lower crust. However, questions remain as to whether apatite faithfully records thermally-activated volume diffusion profiles, or rather is influenced by recrystallization and new growth processes. We present a case study of two apatite samples from the Akia Terrane in Greenland that help chart some of the post magmatic history of this region. Apatite in a tonalitic gneiss has distinct U-enriched rims and its U-Pb apparent ages correlate with Mn chemistry, with a high Mn group yielding an age of c. 2813 Ma. The U-Pb and trace element chemistry and morphology support an interpretation in which these apatite crystals are originally igneous and record cooling after metamorphism, with subsequent generation of discrete new rims. Epidote observed in the sample implies a <600 °C fluid infiltration event associated with apatite rims. The second sample, from a granitic leucosome, contains apparently homogeneous apatite, however U-Pb analyses define two distinct discordia arrays with different common Pb components. An older, c. 2490 Ma, component is associated with elevated Sr, whereas a younger, c. 1800 Ma, component has lower Sr concentration. A depth profile reveals an older core with progressively younger ages towards a compositionally discrete late Paleoproterozoic rim. The chemical and age profiles do not directly correspond, implying different diffusion rates between trace elements and U and Pb. The variation in core ages is interpreted to reflect radiogenic-Pb loss from a metamorphic population during new rim growth. The younger, c. 1800 Ma U-Pb age is interpreted to date new apatite growth from a compositionally distinct reservoir driven by tectonothermal and fluid activity, consistent with regional mica Ar-Ar ages. Results from these two samples show that recrystallization, dissolution and regrowth processes likely formed the younger rim overgrowths, and at temperatures below those often considered to be closure temperatures for Pb diffusion in apatite. The results from these samples imply many apatite grains may not record simple thermally activated Pb diffusion profiles and cautions against inversion of apatite U-Pb data to thermal histories without detailed knowledge of the grain growth/alteration processes. Highlights • Present U-Pb apatite geochronology from the Akia Terrane Greenland • Apatites from the same sample may incorporate different common Pb. • Chemical and age zoning in apatite need not correlate • Dissolution and regrowth forming high U rims is prevalent. • Recrystallization may dominate over Pb diffusion in apatite. [ABSTRACT FROM AUTHOR]

In this paper, we describe gravity flow facies that form the base of the Meiji Reef system in the South China Sea, and discuss their palaeoclimate significance. These Early Oligocene (26.1–23.5 Myr) deposits occur in Well NK1 and comprise a 110.6 m thick succession developed on top of volcanic basement. The deposits can be divided into two intervals, both of which are dominated by debris flow facies. The lower 17.6 m thick interval has a gravel content of 50–65% with parent rocks including dacite, basalt, tuff, and coral reef fragments. From base to top, these units coarsen upward and show increasing gravel contents. Gravel clasts are well-rounded but poorly sorted (diameter 10–350 mm), which, together with their complex composition, indicate transportation by the gravity flows from the near-shore volcanic rock basement to the slope. The upper 93 m thick interval comprises abundant bioclastic materials, including benthic foraminifera, crustal red algae, and red algae detritus, with a few volcanic gravel clasts. The content of volcanic rock gravels decreases towards the top, which may be attributed to the reduction or disappearance of volcanic rocks in the provenance area due to the establishment of coral reef facies that cap the succession and dominate the overlying interval from a core depth of 885.6 m to the seafloor. Based on U-Pb dating, the cap-shaped red algae laminae at the facies transition were formed at 24.6 ± 1.1 Ma, dating the earliest initiation of reef building to end-Oligocene times. The emergence of gravity flow sediments during the early Oligocene may be attributed to the onset of the Antarctic glaciation and concurrent regional tectonic activities that led to a shallowing of the sea. The origin of debris with high roundness characteristics is believed to be associated with transportation along the slope triggered by tectonic and climatic events, resulting in the formation of debris flow deposits. Studying the gravity flow facies at the Meiji Reef system is crucial for determining the onset of reef-building and helps establish the relationship between gravity flow deposition, paleoclimate, and regional tectonic evolution in the South China Sea. • On the volcanic basement of Well NK1 in the South China Sea, unique gravity flow deposits with high roundness and low sorting are developed. • U-Pb dating of carbonate rocks shows that the gravity flow deposits were formed during the Oligocene with an age of 26.1–23.5 Ma, which are debris flow deposition. • U-Pb dating of carbonate rocks shows that the age of the cap-shaped red algae laminae around the gravels are formed at 24.6 ± 1.1 Ma, which is the earliest initiation time of reef building in the Cenozoic. • The emergence of gravity flow deposits during the Early Oligocene is an important sedimentary response to a series of events, including global ice age events, regional tectonic activities, and fluctuations in sea level. [ABSTRACT FROM AUTHOR]

The region of Wallacea has become a hotspot of archaeological research due to significant new discoveries that are changing our understanding and theories about early human history. Anatomically modern humans (AMH) began to migrate and expand to Wallacea and Sahul in Oceania over 45,000 years ago, making this one of the earliest regions with a presence of AMH outside of Africa. Additionally, Sulawesi, the largest island in Wallacea, has yielded the oldest dates for rock paintings worldwide at around 44,000 years ago, predating rock art discovered in Europe. While U-series dating has been used to determine the early rock art, no 14C dates over 40,000 years ago had been reported from Sulawesi, so far. However, in our latest excavation at Goa Topogaro in Central Sulawesi, we obtained 14C dates that support the presence and spread of AMH in Sulawesi by at least 40,000 years ago, if not earlier. The Topogaro cave complex also yielded significant amounts of archaeological remains from various periods during the Late Pleistocene and Holocene, as well as from historical times. Here, we present the major findings of our archaeological research in Goa Topogaro on the eastern coast of Sulawesi and discuss the evidence and timeline for the migration of AMH into Sulawesi Island and their adaptation to the insular environments of Wallacea during the late Pleistocene and Holocene. [ABSTRACT FROM AUTHOR]

Radiocarbon dating of fossil pollen concentrates has the potential to reduce limitations for sample selection in chronological studies of sedimentary archives. The recent development of the technology for rapidly preparing highly purified fossil pollen concentrates using a cell sorter makes it realistic to turn this dream into reality. Before utilizing pollen as a material for dating with confidence, however, it is necessary to understand the factors that may affect the result of the measurements, and to establish criteria to assess the reliability of the radiocarbon ages produced. In this study, peat soils which are commercially available in large quantities, and are hence used as our laboratory standard, as well as the varved lacustrine sediments from Lake Suigetsu, which has one of the best terrestrial radiocarbon stratigraphies in the world, were used to assess the accuracy of radiocarbon ages of pollen concentrates and to establish an appropriate protocol for sample preparation. A pollen-rich fraction prepared by a recently proposed combined method of physio-chemical pre-treatment and cell sorter (Yamada et al. 2021) was submitted to a range of different posterior treatments and radiocarbon measurement. The results were also compared with SEM (Scanning Electron Microscoic) and Fourier Transform Infrared Spectroscopic observations. It was discovered that the sample prepared by the initial pre-treatment and cell sorter were not sufficiently pure and did not yield radiocarbon ages that were consistent with the terrestrial leaf fossils. Instead, the Acid-Base-Acid treatment with ultrafiltration following on from the cell sorter step proved to be highly effective in the removal of contaminants and improve the measured ages. The comparison with Suigetsu's terrestrial radiocarbon dataset also indicated that accuracy could be improved through closer assessment using the pollen taxa composition, carbon content (%C), and stable isotope ratios (δ13C) of the pollen concentrates. The age-depth models established by the radiocarbon dating of fossil pollen grains extracted from the Suigetsu sediments agree very well with that of plant macrofossils, and even improve the precision of the combined model. As long as handling was appropriate, the pollen concentrates prepared by the cell sorter provide reliable radiocarbon ages and the method can significantly contribute to Quaternary sciences in the future. [ABSTRACT FROM AUTHOR]

Abstract A next-generation, high-flux DD neutron generator has been designed, commissioned, and characterized, and is now operational in a new facility at the University of California Berkeley. The generator, originally designed for 40Ar/39Ar dating of geological materials, has since served numerous additional applications, including medical isotope production studies, with others planned for the near future. In this work, we present an overview of the High Flux Neutron Generator (HFNG) which includes a variety of simulations, analytical models, and experimental validation of results. Extensive analysis was performed in order to characterize the neutron yield, flux, and energy distribution at specific locations where samples may be loaded for irradiation. A notable design feature of the HFNG is the possibility for sample irradiation internal to the cathode, just 8 mm away from the neutron production site, thus maximizing the neutron flux (n/cm 2 /s). The generator’s maximum neutron flux at this irradiation position is 2.58 × 10 7 n/cm 2 /s ± 5% (approximately 3 × 10 8 n/s total yield) as measured via activation of small natural indium foils. However, future development is aimed at achieving an order of magnitude increase in flux. Additionally, the deuterium ion beam optics were optimized by simulations for various extraction configurations in order to achieve a uniform neutron flux distribution and an acceptable heat load. Finally, experiments were performed in order to benchmark the modeling and characterization of the HFNG. [ABSTRACT FROM AUTHOR]

U-Pb geochronology requires knowledge of a precise and accurate value for the 238 U/ 235 U ratio of any mineral or material being dated by this method. It is now well established that the long-accepted value of 137.88 is not representative of most terrestrial materials and that the ratio is variant both between and within samples. As most samples used for chronology have insufficient amounts of U to determine a precise isotopic composition, the U-Pb geochronology community has informally adopted the recommended value of 137.818 ± 0.045 based on a single data set of 44 zircons by Hiess et al. (2012). To evaluate the robustness of this value and the true range of U isotopic compositions in U-bearing minerals, we have measured the U isotopic composition of 28 bulk zircon samples as well as several co-existing accessory minerals from rocks with a wide range of ages and geographical distributions. The 238 U/ 235 U ratio of 137.817 ± 0.031 represents the mid-point value of our data with an uncertainty that includes all 28 zircon populations analyzed and their respective uncertainties. This value is indistinguishable from the previously recommended value but with a smaller uncertainty that may reflect the refined analytical methods employed in our study. This result provides confidence to the U-Pb geochronology community that the value recommended by Hiess et al. (2012) is appropriate and that their stated uncertainty appears to be conservative. We find variability in the 238 U/ 235 U ratio of coexisting phases within single samples of up to 2.9 ε-units (parts per 10,000). In addition, our range of U isotopic compositions for zircon is heavier than that reported for bulk continental crust in general and most granitoid intrusive rocks specifically. We attribute these observations to differences in the coordination environment of U in zircon and other U-bearing phases. With the amount of zircon formed in magmatic systems limited by the abundance of Zr, we estimate that the majority of U in granitoid rocks must reside in other phases with a bulk isotopic composition that represents a lighter complement to that of zircon. [ABSTRACT FROM AUTHOR]

Previous studies have shown that radiometric dating of fossils can be complicated by post-fossilisation alteration. A key challenge to obtaining geologically meaningful fossilisation dates in bioapatite is identifying regions that have remained relatively undisturbed since the time of fossilisation. In order to determine whether a geochemical indicator can be used to identify least-disturbed regions, we combine in situ trace element analysis and U-Pb geochronology of fossil teeth from the Arroyo Chijuillita Member, New Mexico, and the Dinosaur Park Formation, Alberta. The reliability of these U-Pb dates is supported by good agreement between the isotope dilution thermal ionization mass spectrometry (61.5 ± 1.6 Ma) and laser ablation ICP-MS (64.2 ± 2.4 Ma) dates for a targeted tooth region. Of fourteen teeth analyzed from these units, two record dates within uncertainty of the depositional age: one has a “diffusion” concave upward cross-sectional yttrium profile, the other a concave downward profile reflective of trace element loss. It was found for teeth from both units that smaller yttrium concentration ranges are correlated with younger U-Pb dates, likely the result of post-fossilisation alteration. A yttrium screen based on this relationship is proposed, and is found to be a better indicator of post-fossilisation open system behaviour in the samples analyzed than other geochemical features thought to be produced during fossilisation. This screen provides a new tool for identifying fossil material least disturbed since fossilisation, facilitating the use of bioapatite to date the time of diagenesis. [ABSTRACT FROM AUTHOR]

Limited chronological information for Upper Jurassic rocks hampers precise age assignment of the Jurassic-Cretaceous (J/K) boundary. This study presents Re-Os geochronology, Rock-Eval pyrolysis and geochemical data for Upper Jurassic rocks in the Nordland VII area, offshore northern Norway. Four intervals of organic-rich shale were investigated, two from the Krill and one from the Alge Member of the Hekkingen Formation and one from the underlying Måsnykan Formation (drilled cores 6814/04/U-01 and 6814/04/U-02). Rock-Eval pyrolysis data indicate immature organic matter with mixed (Type II/III) oil-gas potential in these units. Among the four intervals, Re-Os isochroneity prevails only for the Hekkingen Formation samples; data from the shale interval in the otherwise sand-rich Måsnykan Formation, deposited in a shoreface-to-foreshore marine environment, are not isochronous. Non-isochroneity of the samples from relatively proximal setting is attributable to non-conservative elemental (desorption of Os from sediments to dissolved phase) and isotopic exchange of Os at this depositional site. The Re-Os isochron age for the Alge Member (153.2 ± 7.3 Ma (Model 3); MSWD = 29; n  = 9) is consistent with its biostratigraphic Kimmeridgian age (152.1–157.3 Ma). A Re-Os isochron for the lower part of the Krill Member yields an age of 144.5 ± 1.4 Ma (Model 3; MSWD = 3.7; n  = 10) with an initial 187 Os/ 188 Os ratio of 0.552 ± 0.007. Given the interval's lower Tithonian biostratigraphic age, the Re-Os age suggests that the J/K boundary must be a few Myr younger than its currently assigned age of ~145.0 Ma (2017/02 time scale; www.stratigraphy.org ). A Re-Os model age for shales from the upper part of the Krill Member places an upper age limit for the J/K boundary at 142 (±2) Ma. Hence, the J/K boundary is between 142 Ma and 144.5 Ma. Fe and S concentrations for the Hekkingen Formation show strong correlation and the S/Fe slope (~1.19) mimics the stoichiometric S/Fe ratio for pyrite (~1.15). A Fe-S-TOC ternary diagram for these samples points to an iron-limiting, sulphidic depositional environment. Anoxic to sulphidic depositional conditions for the Hekkingen shales are also evident from relatively higher authigenic enrichment of Mo compared to U. Unlike the Hekkingen Formation, shales from the more sandy Måsnykan Formation have lower S/Fe ratios and lower enrichment factors for redox-sensitive elements, indicating relatively oxygenated marine conditions during deposition. [ABSTRACT FROM AUTHOR]