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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]

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]

• 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]