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Heavy mineral separation reveals the presence of garnet-group minerals and magnetite as well as native gold. Magnetite crystals display the same variability in transport indicators as garnet, and there is a notable decrease in the size of individual crystals and the proportion of magnetite between samples relative to their downstream position. Crystals of smoky quartz and amazonite are present as well as a number of accessory minerals, including several beryllium mineral species. The single-crystal diffraction data of eight plutonic labradorite crystals and one metamorphic labradorite crystal show that they all have the incommensurately modulated structures, characterized by the satellite reflections ( I e i -reflections), which cannot be indexed by integer Miller indices. [Extracted from the article]

In the same year as that paper, Roger published a wide-ranging standalone discussion of various aspects of New Zealand terrane concepts, age, content, interpretation, and paleogeography, including descriptions of the Brook Street Terrane and other Eastern Province terranes (Cooper [13]). Roger Cooper (1939-2020) was one of the pre-eminent New Zealand paleontologists and geologists of the twentieth century. At the same time, and in collaboration with Professor Pete Sadler (University of California, Riverside), Roger pioneered the use of innovative, quantitative methods in biostratigraphic correlation and timescale calibration, in the context both of New Zealand sedimentary basin analysis (Cooper et al. [15]) and international timescale calibration. Much of this research was concerned with graptolites (e.g. Cooper [8], [10]; Cooper and McLaurin [22]) but, in collaboration with others, his interests quickly expanded to include conodonts, brachiopods, molluscs, trilobites and graptolites from New Zealand, Australia, Antarctica and Spitsbergen (e.g. Cooper and Druce [16]; Shergold et al. [48]). Roger's career at the New Zealand Geological Survey began in 1969 and was focussed initially on the taxonomy, biostratigraphy, evolution, biogeography and paleobiology of early Paleozoic fossils in New Zealand. [Extracted from the article]

This paper interrogates how the two major competing frameworks in the debates over framing our geological epoch – the Anthropocene and the Capitalocene – are unified in the reproduction of a Eurocentric assumption that functions to confirm the historical priority of Euro-Western geological agency, the corollary of which is the rendering derivative of non-European peoples as lacking in such capacity until mobilized by Euro-Western forces. Rather than assume that humanity in general, or colonial capitalism more specifically, has generated a novel geological epoch by disrupting the 'natural' temporal divide between deep geological time, medium run biological time, and human history, this paper argues for a more co-constitutive relation between geological, biological, and social space-times. Locating ourselves within an irreducible socio-bio-geological space-time, we re-encounter the earth as multiple earth-worldings co-constituted by Indigenous and Black peoples in ways that precede, and exceed, the hitherto understood to be 'originary' geological capacity of Euro-Western colonial capitalism. [ABSTRACT FROM AUTHOR]

This issue includes seven papers on Cadomian rocks from Bulgaria/Serbia through Turkey to eastern Iran (Figure 2). The most important exposures of Cadomian basements are found in the Strandja Zone, the Istanbul Zone, and the Anatolide-Tauride Block in Turkey, and NW Iranian Block and Central Iranian Microcontinent in Iran (Figure 2). Keywords: Cadomian belt; Pan-African orogeny; Turkey; Iran EN Cadomian belt Pan-African orogeny Turkey Iran 2385 2388 4 10/04/22 20221001 NES 221001 The Cadomian belt (ca. 600-500 Ma) extends from North America through Europe to Iran (Figure 1). [Extracted from the article]

Late Permian to middle Triassic volcanic activities were very strong, however, volcanic records in the early Triassic strata are less reported than those of the Permo-Triassic boundary and the Triassic Olenekian-Anisian boundary in the Yangtze plate, especially within the Sichuan basin. We conduct zircon U-Pb dating and geochemical analysis of the tephra which was first found in the early Triassic Jialingjiang Formation from the Maliuping section, Hechuan, Chongqing. The volcanic ash in the paper yields the new 248.5 ± 0.7 Ma U-Pb age consistent with those of volcanic ashes in these contemporaneous strata in the Yangtze plate. Geochemical characters of whole-rock samples show lower contents in SiO2, K2O and higher components in Al2O3, CaO, MgO, relatively enriched LREE and depleted HREE with distinct negative Eu anomaly, and conspicuous Ba, Nb, Ta, Sr, P, Ti depletion and Th, U, K, Nd enrichment, which is similar to those of the Mung Bean rock of the Triassic Olenekian-Anisian boundary, and those of acidic volcanics from the Sanjiang orogenic belt and Shiwandashan-Qiangfang suture zone during the Early-Middle Triassic. Trace elements of whole rock and analysed zircons of the tuff imply its primary magma derived from Rhyodacite/Dacite and its tectonic setting of volcanic arc granite with continental crust affinity. The early Triassic volcanism during the syn-collision stage of the Paleo-Tethys evolution was less active than those of the Permo-Triassic boundary and the Triassic Olenekian-Anisian boundary, while the volcanic event may have a crucial effect on prolonging fully biotic recovery and entirely ecosystem turnover soon after the Permian-Triassic mass extinction. [ABSTRACT FROM AUTHOR]

Cenozoic magmatism was highly active in the South China Sea (SCS), and mostly dominated by basalts. The magmatic rocks are mainly distributed in the lower slope and subbasins of the SCS, in addition to sporadic and small-scale Cenozoic volcanism on the SCS shelf. This paper presents a complete map of the Cenozoic magmatic rocks of the SCS with magmatic rock boundaries. This paper also presents an analysis of geological survey and published data in terms of seismic profiles, ages, geochemistry and isotopic systematics of the Cenozoic magmatic complexes of the SCS and adjacent areas. Many of wells or dredges are located in magmatic rocks identified by seismic profiles. Three periods of magmatic activity are distinguished: (1) a pre-spreading period (>33 Ma); (2) a syn-spreading period (33–15 Ma) and (3) a post-spreading period (<15 Ma). The thickest volcanic rocks encountered more than 1000 m (possibly Oligocene to Miocene) in the Boayan 1/1A well in the Palawan Trough of the southern SCS during Cenozoic. The oldest magmatic rocks are andesites (62.5 ± 2.2 Ma) in the northern SCS (offshore) and andesites (65 ± 3 Ma) in Penghu (on land). The latest modern magmatic activity was detected in 1923 offshore of a submarine volcanic eruption (10°09´29″N, 109°00′50″E, 20 m below sea level) and along the shore of a volcanic eruption in the Philippines. Cenozoic magmatic rocks of the SCS include at least 1008 rock bodies: the smallest is 0.00012 km2, the largest is 1528 km2 and the total area covers 46,309 km2. The Yangjiang-Yitong fault and Zhongnan-Reedbank fault divide the magmatic rocks into two different sections in the eastern and western SCS. The ages of the magmatic rocks in the eastern SCS are mostly older than those in the western SCS. The magmatic rocks in the northern, southern, eastern, western SCS and adjacent areas, and SCS basin are related to extension, subduction+collision, subduction, extrusion, extension+cooling+subsidence, respectively. [ABSTRACT FROM AUTHOR]

Eocene igneous rocks along the Gangdese belt in southern Tibetan Plateau are important for understanding the India–Eurasia collision and Tibetan Plateau uplift. These magmatic rocks are widely considered to be related to roll-back or break-off of the Neotethyan slab during northward subduction. However, Eocene rhyolites in the northwestern Gangdese belt (SW Qiangtang margin) do not fit either the rollback or breakoff models. This paper investigates these Early Eocene lavas and compares them with contemporaneous igneous rocks along the Gangdese belt via detailed field observations, petrology, zircon geochronology, zircon Lu–Hf isotopes and whole-rock geochemistry. These felsic lavas form large outcrops in western Tibet and have two zircon U–Pb ages of 54.71 ± 0.14 Ma and 54.74 ± 0.27 Ma. They have high SiO2 and alkali contents, FeO*/MgO, and Ga/Al ratios as well as strongly negative Eu anomalies and slightly positive zircon εHf(t) values (+2.5 to +4.4). Both Ti-in-zircon and Zr saturation thermometers confirm high magmatic temperatures (~900°C). They are ferroan, A-type rhyolites. Furthermore, the distinctive low εHf(t) values imply that these rhyolites are likely partial melting products of the southwestern Qiangtang Terrane. The lithosphere in this region undergone long-term shortening and thickening since 80–95 Ma. Pre-thickened lithosphere may be a prerequisite for the Early Eocene delamination, and the simultaneous inducement is a far-field tectonic effect from the India–Eurasia collision. We suggest that: (1) India collided with Eurasia before 55 Ma and triggered delamination to form the Shiquanhe A-type rhyolites on the southwestern Qiangtang margin thereafter; and (2) tectonic stresses related to India–Eurasia collision during the Eocene were transmitted efficiently over large distances. [ABSTRACT FROM AUTHOR]

Wallace Broecker is thought to be one of the greatest living geoscientists. During his fifty-plus year career at the Lamont-Doherty Earth Observatory at Columbia University in Palisades, New York, he has been very prolific and is a highly cited geoscientist. Broecker is probably best known for his theory of global ocean circulation, a 'great ocean conveyor' that transports a significant amount of heat around the globe that can also trigger abrupt shifts in world climate. He unintentionally coined the phrase global warming in the title of one of his many papers and is very active to this day. His diverse research areas include paleoclimatology, environmental science, ocean chemistry, isotope geochemistry, and geochronology. Broecker is the winner of most of the awards in his field, including the Crafoord Prize in Geosciences. [ABSTRACT FROM AUTHOR]

The remnant Comei igneous province in SE Tibet has been recognized as a product of early Kerguelen mantle plume activity. In this paper, we investigate mafic dykes and sills intruded into Lakang Formation in the southeastern Tethyan Himalaya. Based on new whole-rock geochemical, Sr-Nd-Pb isotopic and SHRIMP zircon U-Pb geochronological data, these rocks can be divided into three groups. Group 1 is composed of OIB-like mafic dykes and sills with lower εNd(t) (+1.78-+2.55) and dated at 124.8 ± 1.7 and 133.3 ± 1.5 Ma. Group 2 consists of N-MORB-like mafic dykes and sills with lower TiO2 and P2O5 contents. Group 3 has geochemical compositions transitional between Group 1 and Group 2, with εNd(t) ranging from +1.98 to +2.24 and an age of 125.1 ± 2.1 Ma. We interpret Group 1 as being derived from an OIB-like source related to a mantle plume. Groups 2 and 3 are considered to have been generated from melts of the asthenosphere and the lower crust, with some involvement of melts from the upper crust. Considering the oldest (ca. 147 Ma) and the youngest (ca. 125 Ma) ages of the OIB-like mafic dykes and sills related to the Kerguelen mantle plume and their palaeogeographic location, we suggest that the Kerguelen mantle plume head had reached the lithosphere during the late Jurassic and was later directly underneath the Cona area. We propose a new model to describe the early activity of Kerguelen mantle plume, which put the mantle plume below the mid-ocean ridge and can well explain the long-lived magmatism related to Kerguelen mantle plume. [ABSTRACT FROM AUTHOR]

The Khanka Massif forms the easternmost part of the Central Asian Orogenic Belt (CAOB) and represents an ideal location for examination of the timing and processes involved in the transition from the Palaeo-Asian to Palaeo-Pacific Ocean tectonic systems. However, it is obstructed because the late Palaeozoic tectonic attributes of the eastern margin of this massif remain unclear. In this paper, we provide zircon U-Pb ages and Hf isotopic, as well as the whole-rock Sr-Nd-Pb-Hf isotopic data for Permian granitic and volcanic rocks within the eastern margin of the Khanka Massif, with the aim of exploring the petrogenesis and their geodynamics significance. These data suggest that the Permian magmatism within the eastern margin of the Khanka Massif, composed of monzogranites and rhyolites, can be split into two stages; i.e. middle (ca. 264 to ca. 263 Ma) and late (ca. 252 Ma) Permian. The highly fractionated middle Permian monzogranites are formed in an N-S extensional setting and represent the magmatic response to the amalgamation of the Khanka and Jiamusi massifs. Middle-late Permian rhyolites with decoupled Nd-Hf isotopic compositions were derived from partial melting of metasedimentary crustal rocks. Their moderate-high zircon saturation temperatures (796–817°C) are thought to represent the involvement of ridge subduction of the Palaeo-Asian Ocean beneath the western margin of the Khanka Massif. Our findings further reinforce the existence of the ridge subduction of the Palaeo-Asian Ocean at the western margin of Khanka Massif in the Permian, while excluding the possibility of Permian Palaeo-Pacific oceanic plate subduction occurred beneath the eastern margin of the Khanka Massif in the Permian. [ABSTRACT FROM AUTHOR]

Cadomian (Ediacaran–Cambrian) magmatic rocks have been reported in the eastern (e.g. the Çatalca and İhsaniye plutons) and western (e.g. the Binkılıç and Safaalan plutons) parts of the Istranca (Strandja) Massif. This paper aims to investigate the tectonic setting and the magma evolution history of the Cadomian magmatic rocks using both new and previously existing geochemical and geochronological data. The meta-granitoid rocks with intermediate to felsic composition are the main magmatic activity in the region. They intrude into metamorphic basement rocks composed of gneiss, schist, amphibolite, calc-schist, and quartzites (the Tekedere group). These plutons show strong foliation and traces of the polyphase metamorphism. All plutons are peraluminous and slightly metaluminous, mostly calc-alkaline and high-K calc-alkaline, and plot into the volcanic arc granites (VAG) field on the tectono-magmatic discrimination diagrams. The zircon U–Pb crystallization ages of the plutons are between 525.3 ± 3.5 Ma and 548.7 ± 2.3 Ma. Initial εNd values vary from −0.02 to 1.86. Nd-TDM model ages range between 1.08 and 1.24 Ga and indicate that the primitive magmas were originated and/or assimilated by the remelting of Neoproterozoic juvenile crustal rocks. New geochemical and geochronological data suggest a magma generation within a subduction-related magmatic arc setting in response to the southward subduction of the Proto-Tethys Ocean during the Late Precambrian-Early Palaeozoic period in the Istranca Massif. [ABSTRACT FROM AUTHOR]

Herbert J. Sullivan, a pioneer in the field of palynology, played a crucial role in the founding of the American Association of Stratigraphic Palynologists (AASP) in 1967. Sullivan, originally from Wales, obtained his BSc and PhD from the University of Sheffield and became an expert in Carboniferous miospores. He worked at the Pan-American Petroleum Corporation in Tulsa, Oklahoma, before moving to Calgary, Alberta, where he held various positions at Amoco Canada. Sullivan retired in 1992 and passed away in 2023. His contributions to palynology and the formation of the AASP have had a lasting impact on the field. [Extracted from the article]

Mantle xenoliths from the Middle-Late Jurassic Obnazhennaya kimberlite are often compared with those from the Udachnaya kimberlite (ca. 367 Ma) to inform the evolution of the Siberia craton. However, there are no direct constraints on the timing of the Obnazhennaya kimberlite eruption. Such uncertainty of the kimberlite age precludes a better understanding of the mantle xenoliths from the Obnazhennaya pipe, and thus also of the evolution of the Siberia craton. This paper reports U-Pb ages for both perovskite from the Obnazhennaya kimberlite and rutile in an Obnazhennaya eclogite xenolith. The fresh perovskite formed during the early stage of magmatic crystallization and yields a U-Pb age of 151.8 ± 2.5 Ma (2σ). Rutile in the eclogite xenolith yields an overlapping U-Pb age of 154.2 ± 1.9 Ma (2σ). Because rutile has a Pb closure temperature lower than the inferred residence temperature of the eclogite prior to eruption, the U-Pb isotope system in rutile was not closed until the host eclogite was entrained and delivered to the surface by the kimberlite and therefore records the timing of kimberlite eruption. These data provide the first direct constraints on the emplacement age of the Obnazhennaya kimberlite and add to the global 'kimberlite bloom' from ca. 250–50 Ma as well as to the largest pulse of kimberlite volcanism in Siberia from ca. 171–144 Ma. The timing of this Jurassic–Cretaceous pulse coincides with the closure of the Mongol–Okhotsk Ocean, but the depleted Sr-Nd isotopic characteristics of 171–144 Ma kimberlites are inconsistent with a subduction-driven model for their petrogenesis. Thus, the closure of the Mongol-Okhotsk Ocean may act as a trigger for the initiation of 171–144 Ma kimberlite emplacement of Siberia, but was not the source. [ABSTRACT FROM AUTHOR]

In this paper, we present an integrated study of petrology, zircon U–Pb geochronology, whole-rock geochemistry, and zircon Lu–Hf isotopes for the basic–intermediate dykes in the western Gonghe basin, northeastern Qinghai–Tibetan Plateau. LA–MC–ICP–MS zircon U–Pb dating indicates that these dykes were emplaced in the Middle Triassic (240 ± 1.6 Ma). Geochemically, these basic–intermediate dykes are characterized by enrichments in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs; e.g. K, Rb, and Pb), coupled with depletions in high-field-strength elements (HFSEs; e.g. Nb, Ta, and Ti). These geochemical features, along with the relatively low zircon εHf values (−7.2 to 1.6), suggest that these mafic dykes were originated from enriched mantle metasomatized by subduction-related fluids in a back-arc extensional environment. Literature investigations indicate that Middle Triassic mafic dykes are widespread in central China and are geochemically of arc affinities. Therefore, a regional back-arc extensional event occurred in central China during Middle Triassic time, which was likely caused by rollback of the subducting Kunlun–Animaqin Paleo-Tethyan slab. [ABSTRACT FROM AUTHOR]

Cadomian calc-alkaline I-type and within-plate A-type igneous rocks are widespread in the crust of Iran where they are ascribed to a convergent margin associated with the southward subduction of Prototethyan oceanic lithosphere beneath N Gondwana. These rocks are found as unmetamorphosed magmatic rocks and their metamorphic equivalents (mafic to felsic gneisses) could have been generated in both Cadomian arcs and associated rear-arcs. Nearly all these exposures also contain metamorphosed metasediments, whereas Cadomian igneous rocks of central Iran are associated with thick sequences of unmetamorphosed terrigenous rocks. In the Zagros Fold-Thrust belt of S Iran, salt diapirs contain abundant xenoliths of Cadomian igneous and sedimentary rocks in association with evaporites, dolomites, carbonates, and banded iron-salt deposits. This paper presents new zircon U-Pb and geochemical-isotopic data from igneous clasts in the Chah-Banu salt diapir in SE Zagros. Petrographic and geochemical data indicate two different types of rock clasts; calc-alkaline, I-type dacites-rhyolites, and arc-related to E-MORB-OIB-like gabbros, basalts, and dolerites. New zircon U-Pb ages show that dacites formed at 538.2 ± 2.2 Ma, whereas gabbros show ages of 539.0 ± 1.8 Ma. Zircons from dacites have negative εHf(t) values of – 1.1 to – 8.3. In contrast, zircons from gabbros have higher εHf(t) values of +4.5 to +8.5, indicating crystallization from mantle-derived juvenile magmas. Bulk rock Nd-Sr isotopic data (e.g. ɛNd(t) = +0.3 to +4.0 and 87Sr/86Sr(i) = 0.7059 to 0.70848) for gabbros, dolerites, and basalts confirm that these rocks originated from a mantle source similar to enriched parts of the subcontinental lithospheric mantle, whereas dacites and rhyolites (with εNd(t) = −3.4 to −4.1 and 87Sr/86Sr(i) = 0.70806 to 0.70907) show strong interaction with, and/or re-melting of older continental crust. We suggest that the bimodal calc-alkaline and E-MORB-OIB-like magmatic rocks in salt diapirs as well as associated evaporites and sedimentary rocks formed in a retro-arc rifted basin behind the Cadomian magmatic arc. [ABSTRACT FROM AUTHOR]

Proterozoic to lower Palaeozoic metamorphic sequences are exposed in southern Mexico providing an important geological record for Rodinia and northwestern Gondwana reconstructions. The Sierra de Juárez Complex (SJC) is an enigmatic basement block in southern Mexico that recorded Jurassic dextral strike-slip mylonitic deformation, likely instigated by Pangea break-up and opening of the Gulf of Mexico. However, the origin and pre-Mesozoic evolution of this block are poorly constrained. In this paper, we present the result of fieldwork, LA-ICP-MS U-Pb zircon geochronology, and major and trace element geochemical analyses that allow us to define the following lithological units in the SJC: (1) an anorthositic-gabbroic metamorphic unit (Viguera Suite) with protolith ages of 979–976 Ma and a thermal disturbance event at ca. 920–880 Ma; (2) a MORB-like metagabbroic unit (San Agustín Orthogneiss) with a protolith age of 441.9 ± 3.6 Ma; (3) a metamorphic supracrustal sequence (Etla Unit) that includes amphibolites and pelitic schists with maximum depositional ages of 422–414 Ma and a detrital provenance sourced in Gondwanan-type terranes; and (4) metagranitic intrusions with a protolith age of 191.9 ± 1 Ma, suspected to be syntectonic with respect to the Jurassic mylonitic event. The Silurian-Devonian San Agustín Orthogneiss and Etla Unit constitute the roots of a formerly undocumented lower Palaeozoic terrane that, together with the Viguera Suite, underwent high-pressure amphibolite facies metamorphism between 398–391 Ma, likely related to contractional tectonics. Based on these data, the SJC is proposed as a Mesoproterozoic to middle Palaeozoic crustal block with a geologic evolution coupled to NW Gondwana and a potential correlation with the Grenville-aged and peri-Gondwanan-type terranes like those currently located in southeastern Mexico, Central America, and northwestern South America. [ABSTRACT FROM AUTHOR]

Central to art was once its relationship to the imaginative interior of the artist. The legacy of romanticism and the sublime has been systematically eroded throughout the 20th and 21st centuries. Although for some not entirely lost. Contemporary discourses around the posthuman have played their part in the erasure of the artist, through the breakdown of the centrality of our bodily self in the world, and correspondingly, our imaginative interior as previously conceived has been jettisoned. Through the rise of the anthropocene, attention is now paid to the more or other-than-human, and even for those who take the person as part of this schema, the body is no longer closed, its interior bracketed off from the world, but part of a wider nexus, where fundamentally for the posthuman, the body-mind of the artist is not necessarily the originating source for creativity. This paper seeks to consider the material embodiments of these developments through exploring the working practice of artist Katie Paterson. Multidisciplinary and cross-medium, her work is concerned with immensity and particularity; her material is the stuff of the world, through which she tells the story of nature's elusive phenomena. The artist is quelled and transformed in Paterson's work through a re-articulation of the structures and processes normally hidden from us. In this way the register of the artist shifts and the subjective self is dispersed and reconstructed through alternative frames of reference, most notably geological time and the space of the cosmos. Heir to the romantic sublime, her work offers a reappraisal of the place of artistic subjectivity in the era of the posthuman. In so doing her work reveals the potential for a new posthuman sublime. [ABSTRACT FROM AUTHOR]

Large volumes of Early Cretaceous adakitic rocks crop out in northeast China. In this paper, we summarize their spatial-temporal distribution and geochemical characteristics. These adakitic rocks exhibit variable MgO, Cr and Ni contents, as well as potassium enrichments, in contrasting with those of the slab melting derived adakites. Positive εNd(t) and εHf(t) values and low 87Sr/86Sr(i) indicate significant Phanerozoic crust growth in NE China. Based on their geochemistry, these adakitic rocks are mainly derived from partial melting of juvenile lower crust. We interpret the melting to have resulted from extension and associated delamination. The ages of adakitic rocks are 141–120 Ma in the Xing'an region, 129–113 Ma in the Songliao basin, and 113–90 Ma in the Jiamusi region. Based on the lower-crustal-melting geochemical characteristics and spatial distribution of ages, we propose a new two-stage convergent bidirectional subduction model: Mongol-Okhotsk oceanic plate subduction and associated slab rollback in the west from 141–114 Ma and the Paleo-Pacific oceanic plate subduction and associated slab rollback in the east from 113–90 Ma. [ABSTRACT FROM AUTHOR]

This paper places the territorial politics of digital culture within a material perspective, specifically, through studying forms of labour involved in the mining of rare earths and minerals to generate our digital infrastructures. Following Jussi Parikka's lead in A Geology of Media (2015), I consider the deeper geological time of mineral formation, and analyse the intersection of labour and medianatures. Drawing attention to the exemplification of supply chain capitalism (Tsing), I look at the scales of violence of mining and the dispossession of bodies implicated in two locations in Congo and Australia in the Global South through the lens of performance studies and critical theory. [ABSTRACT FROM AUTHOR]

Percrocutoids are a group of Old World Neogene feliforms whose dentition evokes the adaptations shown by the most evolved forms of Pleistocene hyenas. This paper analyzes the ecomorphology of percrocutoid hyenas based on postcanine dentition from a multivariate metric perspective. Taking non-percrocutoid hyaenids as a reference, species of the genus Percrocuta and some species of the genus Dinocrocuta show a clear convergence with the transitional durophagous morphotypes and fully developed bone-crackers. In contrast, most Dinocrocuta species with increasing size develop very sectorial dentitions showing a clear convergence with the cursorial meat and bone-crackers hyaenids, such as those of the genus Chasmaporthetes. Through geological time, percrocutoids modified their upper dentition to a greater degree than standard hyaenids, while the opposite is observed for the lower dentition. [ABSTRACT FROM AUTHOR]

The metamorphic basement of the Mérida Andes in western Venezuela is constituted of paragneiss, orthogneiss, amphibolite, and metagranitoid of the Iglesias Complex. In this paper, U–Pb zircon geochronology, Lu–Hf, and Sm–Nd isotope systematics of these rocks are presented. Biotite-garnet orthogneiss protoliths intruded paragneiss at ~487 Ma, during Barrovian metamorphism (M1) that reached anatexis at ~467 Ma. Paragneiss and orthogneiss were later intruded by mafic to intermediate lower-crust and mantle-derived magmas (now hornblende orthogneiss and amphibolite) in a back-arc setting at ~460–455 Ma. A new compressional setting led to high-grade metamorphism (M2) at ~450 Ma, followed by decompression melting at ~430–420 Ma (M3). Finally, an upper greenschist- to amphibolite-facies overprint in the complex occurred at ~230 Ma (M4). Ordovician and Late Triassic metagranitoids are probably syn-tectonic to metamorphism M2 and M4, respectively. The Iglesias Complex has several similarities to rocks of the same age in other crustal fragments adjacent to northwest Gondwana, such as the Santander Massif in Colombia, and the Maya block and the Acatlán Complex in southern Mexico and Central America. Both, the early Palaeozoic and the early Mesozoic tectonothermal events, are related to active continental arcs broadly recognized as the Famatinian orogeny and the Proto-Andean Permo-Triassic arc, respectively. No exposures of Rodinia-type basement were found, but isotope systematics suggest that such basement is probably buried underneath the Mérida Andes. [ABSTRACT FROM AUTHOR]

In order of impact, the main anthropogenic threats to caves in eastern Australia are and have been for the European history of Australia: mining, inundation, vandalism, wear and tear, lampenflora, lint and dust, scientists and poorly informed decisions. Destruction of caves by natural processes is not a focus of this paper as it occurs over a geological time scale and there are few historical accounts of natural catastrophic cave failure. Saving and protecting caves are difficult due to the reliance and insistence on conservation by secrecy used by cavers and the organisations that represent them. Other issues that inhibit cave conservation are: limited public exposure, perceptions of land managers and farmers about caves, a shortage of research-based information on caves and difficulties with establishing the significance of a cave. Cave monitoring and the education of managers and cave guides are known to enhance the conservation of show caves. Actions that would help to save and conserve caves throughout Australia include: changes to planning legislation, establishment of a cave conservation organisation, introduction of specific cave protection legislation and the establishment of a Research Centre for Caves, Karst and Geoheritage. [ABSTRACT FROM AUTHOR]

The basal succession of the Condamine Valley, which overlays the boundary between the Surat and Clarence-Moreton basins (eastern Australia), contains a clay-rich horizon 'the Transition Zone' that marks a pronounced unconformity between the Jurassic Walloon Coal Measures and the Quaternary Condamine Alluvium. This paper provides insights into the tectonic and drainage evolution of the Condamine Valley through integrated analysis of U–Pb ages of detrital zircon from three samples (494 concordant analyses), stable oxygen isotope analysis on eight authigenic clay samples, X-ray fluorescence of primary and trace elements, and hyperspectral mineral analysis from two drill cores (Lone Pine 17 and Daandine 164). The Transition Zone is interpreted to consist of both weathered Jurassic sediments and Cenozoic clay deposits. Two sequential cycles of erosion, deposition and pedogenesis, related to geomorphological and climatic conditions are recognised. Distinctive oxygen isotope signatures of the two weathering fronts demonstrated an initial Early Cretaceous phase (δ18O = 11.9–15.7‰ VSMOW) associated with laterisation and possible uplift, followed by Paleogene (δ18O = 16.4–17.3‰ VSMOW) silcretisation of reworked Jurassic sediments. Detrital zircon geochronology yielded Jurassic maximum constraints for the age of deposition of three samples that are indistinguishable within error, the oldest of which (163 ± 8 Ma from the lateritic profile) corresponds to the age of the underlying Walloon Coal Measures. The two overlaying samples from a silcrete profile and granular alluvium yielded overlapping yet younger ages of 150 ± 6 Ma and 156 ± 9 Ma, respectively. Vitrinite reflectance used as a proxy for the thermal condition of the coal strata enabled an estimated 2–3 km of burial and subsequent (likely Early Cretaceous) uplift. Geochemical insights from the Condamine Valley correspond to broad-scale climatic and tectonic conditions, suggesting that 'transition zone equivalents' and corresponding groundwater dynamics may occur in similar sedimentary settings throughout eastern Australia. [ABSTRACT FROM AUTHOR]

This paper reports results from detrital zircon U-Pb geochronology, Hf isotopic geochemistry, sandstone modal analysis, and palaeocurrent analysis of the early Mesozoic strata within the Ningwu basin, China, with the aims of constraining the depositional ages and sedimentary provenances and shedding new light on the Mesozoic tectonic evolution of the northcentral North China Craton (NCC). The zircons from early Mesozoic sandstones are characterized by three major populations: Phanerozoic (late Palaeozoic and early Mesozoic), late Palaeoproterozoic (with a peak at approximately 1.8 Ga), and Neoarchaean (with a peak at approximately 2.5 Ga). Notably, three Phanerozoic zircons in the Early Triassic Liujiagou Formation were found to have positive εHf(t) values and characteristics typical of zircons from the Central Asian Orogenic Belt (CAOB). Therefore, the CAOB began to represent the provenance of sediment in the sedimentary basins in the northern NCC no later than the Early Triassic (261 Ma), implying that the final amalgamation of the NCC and CAOB occurred before the Early Triassic. The U-Pb geochronologic and Hf isotopic results show that the Lower Middle Triassic sediments were mainly sourced from the Yinshan-Yanshan Orogenic Belt (YYOB), and that a sudden change in provenances occurred, shifting from a mixed YYOB and CAOB source in the Middle Jurassic to a primarily YYOB source in the Late Jurassic. The results of the sandstone modal analysis suggest that the majority of the samples from the Lower Middle Jurassic rocks were derived from either Continental Block or Recycled Orogen sources, whereas all the samples from the Upper Jurassic rocks were derived from Mixed sources. The change in source might be ascribed to the southward subduction and closure of the Okhotsk Ocean and the resulting intense uplift of the YYOB during the Late Jurassic. This uplift likely represents the start of the Yanshan Orogeny. [ABSTRACT FROM AUTHOR]

In this paper, laser ablation ICP-MS U-Pb detrital zircon ages are used to discuss provenance and early Palaeozoic palaeogeography of continental fragments that originated in the Cadomian-Avalonian active margin of Gondwana at the end of Precambrian, were subsequently extended during late Cambrian to Early Ordovician opening of the Rheic Ocean, and finally were incorporated into and reworked within the European Variscan belt. The U-Pb detrital zircon age spectra in the analysed samples, taken across a late Neproterozoic (Ediacaran) to Early/Middle Devonian metasedimentary succession of the southeastern Teplá-Barrandian unit, Bohemian Massif, are almost identical and exhibit a bimodal age distribution with significant peaks at about 2.1-1.9 Ga and 650-550 Ma. We interpret the source area as an active margin comprising a cratonic (Eburnean) hinterland rimmed by Cadomian volcanic arcs and we suggest that this source was available at all times during deposition. The new detrital zircon ages also corroborate the West African provenance of the Teplá-Barrandian and correlative Saxothuringian and Moldanubian units, questioned in some palaeogeographic reconstructions. Finally, at variance with the still popular concept of the Cadomian basement units as far-travelled terranes, we propose that early Palaeozoic basins, developed upon the Cadomian active margin, were always part of a wide Gondwana shelf and drifted northwards together before involvement in the Variscan collisional belt. [ABSTRACT FROM AUTHOR]

This paper examines Neanderthal survival skills in Britain. Its starting point is that there are major tensions between the three main sources of relevant information – archaeological, palaeoanthropological and palaeoenvironmental data and their subsequent interpretation – that make our understanding of Neanderthal survival much more precarious than is generally supposed. The paper is speculative, and proffers questions not answers. It challenges us to look past the often mute material record, and to equip Neanderthals with a number of logically prerequisite but generally archaeologically invisible survival tools and practices, beyond the well-trodden paths of mobility, hunting and planning. [ABSTRACT FROM AUTHOR]

Abundant clues about the post-collisional transition in the southwestern margin of the Central Asian Orogenic Belt (CAOB) have been recorded by the late Palaeozoic volcanic rocks in the eastern Junggar region. These volcanic rocks provide a better window for understanding the magmatic and tectonic transition processes. This paper reports detailed petrology, whole-rock and Sr–Nd–Pb isotope geochemistry, andin situzircon U–Pb dating analyses of these volcanic rocks from this region. Systematic geochemical and geochronological studies show that three stages of magmatism were recorded in this area, including ca. 407 Ma and ca. 340 Ma medium-to-high-K calc-alkaline series and ca. 320 Ma alkaline and tholeiite series. The ca. 407 Ma volcanic rocks have calc-alkaline compositions, strong enrichment in large-ion lithophile elements (LILEs) and depletion in high-field strength elements (HFSEs), negative Nb anomalies, and light REE (rare earth element)-enriched patterns. The ca. 340 Ma volcanic rocks, which have similar calc-alkaline compositions and arc geochemical affinities but higher K content, have slightly lower Th/Yb and Ba/Nb values than typical island arc or continental margin volcanic suites. The compositions of the ca. 320 Ma volcanic rocks display a bimodal distribution; the ca. 320 Ma basaltic rocks are chemically similar to oceanic island basalt (OIB) but with slight depletion in Nb and Ta, wheres the acidic rocks show the features of A-type granite. The chemical compositions of these volcanic rocks indicate that the ca. 407 Ma magmatism was subduction related, while the ca. 340 Ma and ca. 320 Ma volcanic rocks were the product of post-collisional magmatism. This transition from ca. 407 Ma to ca. 320 Ma records slab subduction, slab break-off, and slab rollback and provides a plausible explanation for the complex spatial and temporal geochemical evolution of magmatism in eastern Junggar since the Devonian. [ABSTRACT FROM AUTHOR]

The advent of chemical abrasion-isotope dilution thermal ionisation mass spectrometry (CA-IDTIMS) has revolutionised U–Pb dating of zircon, and the enhanced precision of eruption ages determined on volcanic layers within basin successions permits an improved calibration of biostratigraphic schemes to the numerical time-scale. The Guadalupian and Lopingian (Permian) successions in the Sydney, Gunnedah, Bowen and Canning basins are mostly non-marine and include numerous airfall tuff units, many of which contain zircon. The eastern Australian palynostratigraphic scheme provides the basis for much of the local correlation, but the present calibration of this scheme against the numerical time-scale depends on a correlation to Western Australia, using rare ammonoids and conodonts in that succession to link to the standard global marine biostratigraphic scheme. High-precision U–Pb zircon dating of tuff layers via CA-IDTIMS allows this tenuous correlation to be circumvented—the resulting direct calibration of the palynostratigraphy to the numerical time-scale highlights significant inaccuracies in the previous indirect correlation. The new data show: the top of thePraecolpatites sinuosusZone (APP3.2) lies in the early Roadian, not the middle Kungurian; the top of theMicrobaculispora villosaZone (APP3.3) lies in the middle Roadian, not the early Roadian; the top of theDulhuntyispora granulataZone (APP4.1) lies in the Wordian, not in the latest Roadian; the top of theDidecitriletes ericianusZone (APP4.2) lies in the first half of the Wuchiapingian, not the latest Wordian; theDulhuntyispora dulhuntyiZone (APP4.3) is exceptionally short and lies within the Wuchiapingian, not the early Capitanian; and the top of theDulhuntyispora parvitholaZone (APP5) lies at or near the Permo-Triassic boundary, not in the latest Wuchiapingian. [ABSTRACT FROM PUBLISHER]

The INTIMATE (Integration of ice-core, marine and terrestrial records) project, the successor to the North Atlantic Seaboard Programme of International Geological Correlation Programme (IGCP-253) ‘Termination of the Pleistocene’, began in 1995 with the aim of integrating proxy climate records from around the North Atlantic during the Last Termination (18–8 ka BP). The INTIMATE remit has since expanded geographically to include the entire Atlantic basin and Australasia, while an extended temporal framework now covers the early Holocene and the Last Glacial cycle. This short paper outlines the principal achievements of the INTIMATE research community, which include the development of an event stratigraphy for the North Atlantic region; the establishment of protocols for ice–land–ocean correlation; important contributions to geochronology, most notably to tephrochronology, and to palaeoenvironmental and palaeoclimatic reconstructions; and the designation of the Greenland ice-core record as the global stratotype for the Pleistocene–Holocene boundary. Future directions of the INTIMATE programme are also briefly considered. [ABSTRACT FROM AUTHOR]

Caledonian nappes of southern Norway comprise basement slices and sedimentary cover, and generally have close affinity with autochthonous terranes in the Fennoscandian foreland. The nappes can be distinguished in those having Gothian (1700–1600 Ma) character and those of Telemarkian (1550–1480 Ma) type. There were also several periods of variously intense magmatism between these early accretionary events and the end of the Sveconorwegian Orogeny. Most prominent features are the anorthositic-noritic massifs, which formed mainly during the Telemarkian period and in the late stages of the Sveconorwegian Orogeny between 980 and 920 Ma. In this paper, we review the main events affecting the crystalline parts of the nappes and report new results from the Eikefjord Nappe. An augen gneiss yields a crystallization age of 1191 ± 2 Ma, which is an event rarely seen in nappes or the autochthon. An amphibolitic gneiss formed at about 1500 Ma and underwent high-grade metamorphism at 986 ± 3 Ma, followed by lower grade overprints as reflected by titanite dates ranging to 915 Ma. The Sveconorwegian metamorphism was ubiquitous in the nappes, although its intensity was locally highly variable. The association of metamorphism with the second main anorthosite generation event points to intense subcrustal magmatism, heating and deformation of the lithosphere. The various crustal forming events have different geneses, some are clearly related to subduction processes, others more consistent with localized mantle melting. Those closer in character to classical Large Igneous Provinces are the events at 1470–1420, 1280–1240 and 1220–1180 Ma. [ABSTRACT FROM PUBLISHER]

Palaeoproterozoic (ca. 1.8 Ga) mafic and ultramafic dykes are widely distributed within the whole Sarmatian segment of the East-European craton. This paper focuses on new geochronological, geochemical and isotope data obtained for mafic and ultramafic dykes of the Ingul terrain. Geochronological data available for these dykes indicate ages around 1800 Ma. We provide a new U–Pb zircon age of 1810 ± 15 Ma obtained for a dolerite dyke in the Kirovograd area. Geochemical and petrographical data allow identification of three groups of dykes: (1) kimberlites, (2) high-Mg# subalkaline rocks (picrite, camptonite, subalkaline dolerite etc.) and (3) tholeiite dolerite. Rocks of these groups were probably derived from different sources. εNd1800values of studied rocks vary from 0.7 to 2.8. The highest values were obtained for mantle xenoliths and their kimberlite host (εNd1800 = 2.5–2.8). Rb–Sr data yield a regression age of 1729 ± 20 Ma with an initial87Sr/86Sr = 0.70366 ± 41 (MSWD = 10.8). The whole-rock lead isotope data scatter, but data for sub-groups of samples can tentatively be fitted to parallel 1.8 Ga isochrons. The geochemical data indicate rocks to have formed by partial melting and the degree of melting is thought to be a function of formation depth, the latter ranging from sub-lithospheric to lower-crustal levels; we assume that melting was caused by a mantle plume. Dyking in the Ingul terrain was closely associated in time and space with metasomatic albitites that host numerous economic U deposits. [ABSTRACT FROM PUBLISHER]

This paper presents the result of my research in Sweden and my view on the relationships between physical geography (here mainly geomorphology) and geology. I developed a method for identification and mapping denudation surfaces formed in the Precambrian basement. South Sweden turned out to be a key area with cover rocks of different age directly on the basement. The relief differences in the basement are connected to the different sedimentary covers with a flat and inclined sub-Cambrian surface and a hilly and inclined sub-Cretaceous surface. The crosscutting horizontal South Småland Plain was classified as a peneplain, as it is a surface graded to a distinct base level. Besides the basement forms and remnant cover rocks, saprolite remnants are important for the identification of denudation surfaces. The mapping method was ultimately labeled Stratigraphic Landscape Analysis (SLA) and used for conclusion on tectonics (uplift/subsidence and faulting). I obtained, as a physical geographer, a broad holistic knowledge on the relief differentiation of the basement rocks of Fennoscandia and on Swedish regional geology. This gave me the tool to identify denudation surfaces with the aid of the new digital elevation data and new geological knowledge of the surrounding continental shelf. The Swedish knowledge on the relationships between relief in the basement and its cover rocks is unique in the world. Maybe the relationship between denudation surfaces, cover rocks and tectonics ought to be a part of geology. Results of measurements, by different new techniques, are nowadays often analyzed based on hypotheses/theories. Observations of field conditions have become difficult to perform both within geology and geomorphology and seem to be considered as unscientific. Further, regional analysis, typical for geography, does not exist anymore. [ABSTRACT FROM AUTHOR]

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Remains of 17thcentury cabinets of curiosity collections are held at the Museum of Evolution, Uppsala University, Sweden. Some of the oldest date back to the 1650s, and were included in the collection of Archiater, i.e. physician to the Crown, von Bromell (1679–1731). He is also known for publishing the first series of papers in Sweden to exclusively deal with palaeontology. Throughout his life he acquired specimens by collecting, buying or receiving in exchange to add to those he inherited from his father Olaus Bromelius, a famous botanist and physician. Information on the labels gives a glimpse of his network of friends, colleagues and fellow collectors, such as Kilian Stobaeus, Lars Roberg, Emanuel Swedenborg, Elias Brenner and Johan Döbelius. When Bromell died, his vast collections of books, coins, furniture, conchs, stuffed animals, minerals and fossils were sold off. The minerals and fossils were split up and owned by various persons during the following century. Parts owned by A. Lagerberg between the years 1746 and 1776 were bought in 1796 by Johan Afzelius and donated to Uppsala University at his death. Fossils and minerals earlier described by Bromell were in the care of The Royal Society of Science in Uppsala at least by 1791. Through the Institute of Geology, fossils accumulated over the centuries at Uppsala University eventually came together under the same roof in 1932, under professor Carl Wiman's care at the then newly erected Palaeontology museum building. Today, about 300 fossils from the Bromell collection are preserved at the museum. [ABSTRACT FROM PUBLISHER]

Basaltic porphyries from the northeast North China craton (NCC) provide an excellent opportunity to examine the nature of their mantle source and the secular evolution of the underlying mantle lithosphere. In addition, the study helps to constrain the age and the mechanism of NCC lithospheric destruction. In this paper, we report geochronological, geochemical, and Sr–Nd isotopic analyses of a suite of mafic lavas. Detailed laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) zircon U–Pb dating yielded an age of 223.3 ± 1.1 million years, which we regard as representing the crystallization age of the basaltic porphyries. The bulk-rock analysed samples are enriched in both large ion lithophile elements (LILEs) (i.e. Ba, Sr, and Pb) and light rare earth elements (LREEs), but depleted in high field strong elements (HFSEs) (i.e. Nb, Ta, Zr, Hf, and Ti) and heavy rare earth elements (HREEs), without significant Eu anomalies (Eu/Eu* =  089–0.98). The basaltic porphyries have undergone low degrees (∼5%) of partial melting of a garnet-bearing lherzolite mantle. The rocks display very uniform (87Sr/86Sr) i (0.70557–0.70583) and negative ϵNd (t) values (–11.9 to –10.1). These features indicate that the western Liaoning basaltic porphyries were derived from a common enriched lithosphere mantle that had previously been metasomatized by fluids related to subduction of Palaeo-Asian sedimentary units. However, the mafic melts were not affected to a significant degree by crustal contamination. Based on earlier studies, these findings provide new evidence that the northeast margin of the NCC had undergone a phase of post-orogenic extensional tectonics during the Middle Triassic. Furthermore, lithospheric thinning occurring across the northern NCC might have been initiated during Early Triassic times and was likely controlled by the final closure of the Palaeo-Asian Ocean, as well as the collision of Mongolian arc terrenes with the NCC. [ABSTRACT FROM AUTHOR]

The 40Ar/39Ar technique is a powerful geochronological method derived from the K/Ar technique that can help to unravel the evolution of the solar system. The 40Ar/39Ar system can not only record the timing of volcanic and metamorphic processes on asteroids and planets, it finds domain of predilection in dating impact events throughout the solar system. The 40Ar/39Ar method is a robust analytical technique when the events to be dated are well understood and data are not over interpreted. The power of the 40Ar/39Ar technique resides in the ability to check the validity of age data internally by statistical means and multiple lines of evidence, and hence to evaluate when Ar age data are unreliable. Yet, too many ‘ages’ reported in the literature are still based on over-interpretation of perturbed age spectra. This review is by no means exhaustive and is centred on the most recent applications of the 40Ar/39Ar technique applied to planetary material, not the history of the planetary bodies themselves, or a historical review of the development of the argon dating technique. This paper presents selected case-study examples on terrestrial impact structures, the Moon and meteorites with ages recalculated using the latest decay constants. Currently, only 21 terrestrial impact structures are precisely and accurately dated, and the only proven age concordance is between the Chixculub impact and the Cretaceous/Paleogene mass extinction. 40Ar/39Ar dating of volcanic events on the Moon suggests that volcanism was concentrated between 3.8 and 3.1 Ga. The study of lunar volcanism would also benefit from dating of volcanic spherules for which only few data are available. Rigorous filtering of the 40Ar/39Ar age database of lunar melt breccias yielded concordant ages with high precision for two major basins of the Moon, but more precise age data would be needed to further test and validate the Late Heavy Bombardment (LHB) hypothesis. 40Ar/39Ar dating of lunar impact spherules shows an increase of ages <400 Ma suggesting a recent increase in the impact flux. The impact history of the LL parent body (bodies?) has yet to be well constrained but may mimic the LHB observed on the Moon, which would indicate that the LL parent body was quite large. Basaltic meteorites (HEDs) show an 40Ar/39Ar age range between 4.1 and 3.4 Ga, suggesting a diffuse LHB event; however, the spread of apparent ages may be a data-interpretation artefact, and the LHB parent body (bodies?) might have experienced a bombardment closer to the duration of the LHB age range than expected. Martian meteorites contain clues on Mars atmospheric and mantle argon compositions. [ABSTRACT FROM AUTHOR]

John Joly was an Irish engineer and geologist who in the 1880s attempted to explain the formation of Cambrian markings known as Oldhamia to the freezing of sediment and the development of surface frost. He also noted differences in the preservation of two forms of Oldhamia when found together in the same bed; these were either as a positive or negative. Oldhamia also inspired Joly to write a sonnet in which he considered geochronology, denudation and the history of life. A detailed interpretation of Joly's sonnet is provided for the first time. [ABSTRACT FROM PUBLISHER]

The Eastern Qinling region, located in the southern margin of the North China Craton, is characterised by widespread granitoid intrusions. Precise geochronological constraints on the age and timing of these intrusions are lacking. In this paper, we report SHRIMP zircon U-Pb ages of 12 representative granitoid plutons, together with one syenite stock, dolerite, diorite and granitic dykes in Eastern Qinling. The results revealed two main magmatic events, which occurred in the Late Jurassic-Early Cretaceous (158 ± 3 to 136 ± 2 Ma) and the Early Cretaceous (134 ± 1 to 108 ± 2 Ma), respectively. The granitoids formed in the early magmatic event are similar in composition and are characterised by a mantle source mixed with variable amounts of crustal components, whereas those resulting from the late-stage magmatism show characters of I-, S- and A-types granite and coexist with coeval dolerite dykes and syenite stocks. A similar magmatic age distribution is also recognised in other belts or regions in East China, and even in other parts of the East Eurasian continental margin. This suggests that the Jurassic-Early Cretaceous magmatism was associated with the subduction of the Izanagi plate at a shallow angle or flat-slab subduction beneath the eastern China continent, whereas the Early Cretaceous magmatism was related to lithospheric thinning, asthenospheric upwelling and partial melting of the lower crust, induced by a change in Izanagi plate motion parallel to the continent margin. [ABSTRACT FROM AUTHOR]

This paper is a synthesis of structural and geochronological data from eastern Mediterranean ophiolitic metamorphic rocks and surrounding units to interpret the intra-oceanic subduction and ophiolite emplacement mechanism. Metamorphic rocks occur as discontinuous tectonic slices at the base of the ophiolites, generally between the peridotite tectonites and volcanic-sedimentary units, and locally in fault zones in the overlying peridotites. They consist essentially of amphibolite, and in lesser quantities, micaschist, quartzite, epidotite and marble. Geological and geochronological data indicate that recrystallization of the metamorphic rocks occurred in the oceanic environment. The contact between the metamorphic rocks and the hanging-wall is parallel to the foliation of the metamorphic rocks, and is interpreted as the fossil plane of intra-oceanic subduction. Structural relationships suggest that intra-oceanic subduction was situated between two lithospheric blocks separated by an oceanic fracture zone. Therefore the Neotethyan ophiolites with metamorphic soles represent the remnants of the overriding oceanic lithosphere's training slices of the metamorphic rocks at the base. In the Anatolian region, radiometric dating of metamorphic rocks from the Taurus and Izmir-Ankara-Erzincan zone ophiolites yield nearly identical ages. Besides, palaeontological and structural data indicate coeval opening and similar oceanic ridge orientation. Consequently it is highly probable that Taurus and Izmir-Ankara-Erzincan zone ophiolites represent fragments of the same oceanic lithosphere derived from a single spreading zone. Palaeontological data from underlying volcanic and sedimentary units point out that the opening of the Neotethyan ocean occurred during Late Permian-Middle Triassic time in the Iranian-Oman region, during Middle Triassic in Dinaro-Hellenic area, and finally during Late Triassic in the Anatolian region. Radiometric dating of the metamorphic rocks exhibit that the intra-oceanic thrusting occurred during late Lower-early Late Jurassic for Dinaro-Hellenic ophiolites, late Lower-early Late Cretaceous for Anatolian, Iranian and Oman ophiolites well before their obduction on the Gondwanian continent. Neotethyan ophiolites were obducted onto various sections of the Gondwanian continent from late Upper Jurassic to Palaeocene time, Dinaro-Hellenic ophiolites during late Upper Jurassic-early Lower Cretaceous onto the Adriatic promontory, Anatolian, Iranian and Oman ophiolites from late Lower Cretaceous to Palaeocene onto the Aegean, Anatolian and Arabic promontories. [ABSTRACT FROM AUTHOR]

The article discusses various reports published within the issue, including "Brief history of Isotope Geology at the Australian National University," and "Geochronology in New South Wales."

The landscapes and archaeological sites of the southern North Sea, drowned in the period 12–6 ky BP, represent an almost unexplored field of research. Published palaeoenvironmental reconstructions are largely speculative, being based on few published sea-level index points and in the absence of detailed physical and chronological surveys. In this paper, we review the post-glacial geochronology for the southern North Sea, which includes 54 radiocarbon ages derived from peat, 17 from molluscs and one known dated artefact. The lack of detailed contextual information for many dated samples means that there remains uncertainty in some elevation data, and thus in the resulting interpreted sea level. The archaeological artefacts are mostly derived deposits and thus are of limited use in palaeoenvironmental reconstruction. Overall, the data are consistent with current models of relative sea-level change back to about 10 ky BP (∼45 m depth) but beyond this, there is very little published data. Much more detailed stratigraphic, microfossil and geochemical analysis is needed to help verify chronological data, help interpret the sedimentary settings in which fossils and artefacts are found, and contribute towards more reliable palaeoenvironmental and archaeological reconstructions of the history of the southern North Sea. [ABSTRACT FROM AUTHOR]

In application of radioactive isotope systems ( \hbox{K}\ndash \hbox{Ar},\hbox{Rb}\ndash \hbox{Sr} etc.) during the last decades, experience was gained not only on their geochronometrical uses, but also on estimations of some important parameters of geological processes,'especially temperatures and durations of superimposed thermal events. In this paper, the formation of an exocontact thermal field of a magmatic intrusion is considered as a spreading of a thermal source delta-function. Appropriate solutions of the heat-transfer equation are deduced and correlated with diffusion parameters of the radiogenic argon, coupling radioactive, thermal and kinetic parameters in an exocontant zone of a magmatic body. These solutions were used for quantitative reinterpretations of data taken from Hart's classical paper [The petrology and isotopic mineral age relations of a contact zone in the Front Range, Colorado. J. Geol., 1964, v. 72, pp. 493-525]. Theoretic and measured radiogenic argon and strontium concentrations within exocontact aureoles are found to be in good concordance. [ABSTRACT FROM AUTHOR]

Significant improvements, both in understanding the evolution of zircons and in understanding the geotectonic and metallogenetic evolution of the complex terrain of southern Brazil, are obtained from a SHRIMP geochronology study and reviewed in this paper. The use of backscattered electron and cathodoluminescence images, prior to SHRIMP isotopic determinations, proved of enormous fundamental value for this technique. Zircon is a domainal open-system mineral in many geological conditions; very old domains may be preserved, but the same crystal may show ages of younger tectonic events. Zircons may recrystallise inwards from the rims or outwards from the cores, and also along euhedral high-U or metamict thin zones. Zircons also may be recrystallised during gold-related hydrothermalism, phyllic alteration of granitic rocks. The precise dating of amphibolite dykes can be achieved by the identification and dating of magmatic zircons. Precambrian orogenies are identified along with the intervening intracratonic tectonic cycles of supercontinents in southern Brazil from 3300 to 470 Ma. Granulite protoliths were formed during the Jequié Orogeny (ca 2600 Ma), but extensive arc accretion occurred in the Palaeoproterozoic (ca 2250 Ma) Encantadas Orogeny. Late in the Transamazonian Cycle, granites were formed by crustal melting at about 2000 Ma in the Camboriú Orogeny. Both accretionary and collisional orogenies are also identified in the Neoproterozoic Brasiliano Cycle. These are the accretionary Passinho Orogeny (ca 900 Ma) and São Gabriel Orogeny (ca 700 Ma), that were succeeded by the collisional Dom Feliciano Orogeny (ca 600 Ma). Base-metal and gold deposition occurred in juvenile island arcs and in late orogenic porphyry-copper-type magmatic–hydrothermal settings during the Neoproterozoic. [ABSTRACT FROM AUTHOR]

New stratigraphic, geochemical and palaeomagnetic data from the Peters Creek Volcanics are used to revise the correlations of part of the Palaeoproterozoic of northern Australia. The revised geological history for these cover rocks of the Murphy Inlier is extrapolated into the 1800–1700 Ma successions of the McArthur Basin and Mt Isa regions. New stratigraphic subdivisions and relationships are contrasted with the established lithostratigraphic schemes and also with conflicting published tectono-stratigraphic interpretations. For the first time, a plethora of stratigraphic units can be rationalised into two major superbasins, the Leichhardt and Calvert Superbasins, and into eight pseudo-chronostratigraphic basin phases (Associations A–H). There are few absolute age constraints, but lateral correlations of the units in these eight basin phases are proposed. Results from the overlying Isa Superbasin (<1670 Ma) suggest that these eight associations probably represent second-order supersequences. Mixed non-marine and marine coarse clastics, deposited between about 1790 and 1780 Ma dominate Associations A and B. In the Mt Isa region these were deposited in an initial rift then a thermal relaxation or sag phase. To the northwest, however, the succession is dominated by rift facies. Association C is a widespread flood basalt and immature clastic suite that was deposited in clearly defined, north-trending half-grabens in the Mt Isa region. Along the southern edge of the Murphy Inlier, however, geophysically defined half-grabens, filled with magnetic rocks (basalt), trend orthogonal to those at Mt Isa. North of the inlier Association C is much thinner, and little can be deduced about its palaeogeography. Association D is only present in the Mt Isa region as the Myally Subgroup. Differing views on its tectonic setting and environments of deposition, as presented in recent papers, are reviewed. Association E, deposited around 1755 Ma, is a regional sag phase... [ABSTRACT FROM AUTHOR]

Paul Bishop's contribution to the earth sciences is profound. His work on large spatial and temporal scale landscape evolution is well known, but he also (and coevally) directed his attention to the complexities of human–environmental interactions, with all their site-based and short-term cultural idiosyncrasies. His focus on mainland SE Asia, and Thailand in particular, reflects a long-standing fascination in and affection for the region and its people. His natural inquisitiveness stimulated work in historic climate change, the emergence of complex states, Quaternary landscape evolution and the geochronology of anthropogenically modified sediments, among many other areas. His work on human–environment interactions drew on and strengthened links with many people and institutions, and between Geographical and Earth Sciences and the Scottish Universities Research Centre at the University of Glasgow, in particular. Just as important as his contribution to the earth sciences was his contribution to the development of his students and other mentees, and his role in shaping our careers was enormous. [ABSTRACT FROM AUTHOR]

Crocodylomorph eggs and eggshells are known as old as the Late Jurassic and are frequent components of most multiootaxic eggshell assemblages. Classified within the oofamily Krokolithidae, thei histo- and ultrastructures are conservative throughout geological time, characterised by inverted-trapezoid-shaped shell units that grow from highly spaced basal knobs and present a diagnostic tabular ultrastructure. Here, we report 327 eggshell fragments from a new fossil site from the Maastrichtian of the Southern Pyrenees, Veracruz 1, and erect a new oogenus and oospecies, Pachykrokolithus excavatum oogen. et oosp. nov. characterised by crocodyloid morphotype and a prominent rugosocavate ornamentation. Eggshells from the slightly older locality of Blasi 2b, previously reported as aff. Krokolithidae, are also assigned to this new ootaxon. Different crocodylomorph taxa coexisted during the Late Cretaceous of the Tremp Basin, hindering the attribution of Pachykrokolithus excavatum oogen. et oosp. nov. to a single clade. Nevertheless, allodaposuchid eusuchians were dominant in this ecosystem, and are the most probable producers of Pachykrokolithus excavatum oogen. et oosp. nov. eggs. [ABSTRACT FROM AUTHOR]