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<jats:p> The formation and dynamics of granitoids in an intra-continental setting are crucial for understanding the architecture and evolution of continental crust. Here, we report geochronological, geochemical and Sr–Nd–Hf isotopic data for newly discovered late Mesozoic granitic intrusions in the Tianshan belt, northwestern China. These granitoids are I-type granites derived from an igneous precursor and were emplaced at <jats:italic>c</jats:italic> . 145–132 Ma. They have positive <jats:inline-formula> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ε</mml:mi> </mml:math> </jats:inline-formula> <jats:sub>Nd</jats:sub> ( <jats:italic>t</jats:italic> ) values and young Nd model ages, together with relatively low Sr/Y ratios, indicating that they might have originated from partial melting of the juvenile lower crust. There is a prominent decoupling between zircon Hf and bulk-rock Nd isotopes, which may have resulted from the early crystallization of Ti-rich minerals. These granitic intrusions also display subduction-related geochemical characteristics, which are probably inherited from Paleozoic crustal sources that were metasomatized by subduction-related fluids. We conclude that these late Mesozoic granitoids were emplaced in an intra-continental setting, and were probably triggered by thermal relaxation owing to crustal shortening and thickening. These data further imply that the Tianshan changed into crustal reworking during the Mesozoic from its prominent crustal growth in the Paleozoic. </jats:p> <jats:p content-type="supplementary-material"> <jats:bold>Supplementary material:</jats:bold> LA-ICP-MS zircon U–Pb dating results, whole-rock major and trace element compositions, whole-rock Sr–Nd isotopic data and zircon Lu–Hf isotopic data are available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" specific-use="dataset is-supplemented-by" xlink:href="https://doi.org/10.6084/m9.figshare.c.7167890">https://doi.org/10.6084/m9.figshare.c.7167890</jats:ext-link> </jats:p> <jats:p content-type="thematic-collection"> <jats:bold>Thematic collection:</jats:bold> This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change">https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change</jats:ext-link> </jats:p>

<jats:p>The North Scotia Ridge is the offshore morphostructural expression of the left-lateral transcurrent South America–Scotia plate boundary. Several blocks make up the ridge, including the scarcely studied Namuncurá Bank (also known as the Burdwood Bank). We present the first detailed study of active structures on the seafloor of the western Namuncurá Bank from a database of 3D and 2D seismic data, multibeam bathymetry and sub-bottom profiles. This work assesses the architecture, style of deformation and Cenozoic evolution of Namuncurá Bank, where several groups of faults and en echelon folding affect the seabed and shallow sub-bottom. These features compound the northernmost structures associated with a releasing bend, fitting well with a left-lateral Riedel shear model oriented at N74°E, slightly rotated with respect to the present day plate boundary stress regime. The current tectonic scenario started with a main deformational phase in the Neogene, partially distributed by the Malvinas fold–thrust belt, while modern deformation continues to be conditioned by pre-existing structures. This study allows a better understanding of the tectonics of the North Scotia Ridge, a morphostructure that influences the circulation of the Antarctic Circumpolar Current, thus impacting the global climate.</jats:p>

<jats:p> Zircon is a common mineral in nature that survives varied pressure and temperature conditions in the subduction process. It has excellent ability to reveal progressive metamorphic history and, hence, is useful in reconstructing the subduction tectonics in collisional orogenic belts. In the Tso Morari Gneiss of the Indus Suture Zone, Himalaya, eclogite boudins have registered the imprint of subduction-related ultrahigh-pressure (UHP) metamorphism; this imprint is, however, missing in the host gneisses. To search for the missing link, zircons of the gneisses were studied. The zircon overgrowth and the numerous mineral inclusions indicate the metamorphic responses of the gneisses. The Raman spectra of minerals show the cores of the zircon consist of apatite and quartz and the surrounding overgrowth preserves quartz–coesite, c-polymorphs and other metamorphic minerals. The distribution pattern of these minerals in the zircons is consistent with the Th/U ratios ranging from 0.30 to 0.01, recognizing the inner magmatic and outer metamorphic domains. The U–Pb ages from the inner magmatic (at <jats:italic>c.</jats:italic> 500 Ma) and from the outer metamorphic growth (at <jats:italic>c.</jats:italic> 45–42 Ma) suggest the former is the protolith age and the latter the metamorphic age of the gneisses. The tectonic interpretation reveals the subduction of Indian felsic crust to UHP depth (&gt;100 km) at <jats:italic>c.</jats:italic> 45 Ma. </jats:p> <jats:p content-type="supplementary-material"> <jats:bold>Supplementary material</jats:bold> : Raman spectra of C-inclusions in the zircon of Tso Morari Gneiss are available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" specific-use="dataset is-supplemented-by" xlink:href="https://doi.org/10.6084/m9.figshare.c.7168228">https://doi.org/10.6084/m9.figshare.c.7168228</jats:ext-link> </jats:p> <jats:p content-type="thematic-collection"> <jats:bold>Thematic collection:</jats:bold> This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change">https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change</jats:ext-link> </jats:p>

<jats:p>The early Silurian Llandovery–Wenlock boundary interval is marked by significant marine perturbations and biotic turnover, culminating in the Ireviken Extinction Event and the Early Sheinwoodian Carbon Isotope Excursion. Here, we apply multiple independent redox proxies to the early Wenlock Buttington section, which was deposited in a mid-shelf location in the Welsh Basin, UK. To account for the regional geochemical variability in marine sediments due to factors such as sediment provenance, we first define oxic baseline values for the Welsh Basin, utilizing deeper water, well-oxygenated intervals of late Llandovery age. Our approach documents unstable, oscillating redox conditions on the mid-shelf at Buttington. We suggest that these dynamic redox fluctuations are likely to relate to changes in the position of the chemocline or a migrating oxygen minimum zone. Benthic biota, such as trilobites, brachiopods, bivalves and gastropods, appear to have been relatively unaffected by fluctuating oxic-ferruginous conditions, but were more severely impacted by the development of euxinia, highlighting the inhibiting role of toxic sulfides. By contrast, the redox perturbations appear to have placed extreme stress on graptolites, causing many extinction losses regardless of the specific development of euxinia.</jats:p> <jats:p content-type="supplementary-material"> <jats:bold>Supplementary material:</jats:bold> The geochemical data for the Buttington section is available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" specific-use="dataset is-supplemented-by" xlink:href="https://doi.org/10.6084/m9.figshare.c.7165009">https://doi.org/10.6084/m9.figshare.c.7165009</jats:ext-link> </jats:p> <jats:p content-type="thematic-collection"> <jats:bold>Thematic collection:</jats:bold> This article is part of the Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response collection available at: <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system">https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system</jats:ext-link> </jats:p>

<jats:p>The Zhu 3 Depression is located at the transition between the South China Sea and the South China Block. The Cenozoic structure reflects the dynamic background of the South China Sea. We used 3D seismic and log data to study the structural evolution of the Zhu 3 Depression. We defined the characteristics of Cenozoic rift deformation and the migration of the depocentre based on fault activity and the distribution of sediment thickness. The spatial and temporal differences in the Cenozoic structure of the Zhu 3 Depression are due to the influence of pre-existing faults and regional stresses. Our results show that there are three populations of faults in the Zhu 3 Depression, striking NE, east–west and NW. The NE-striking faults are mainly large-scale boundary faults. The east–west-striking faults are small and were activated in the later stages of deformation. The NW-striking faults are continuous at depth, but are en echelon and parallel to each other at shallow depths. Based on these results, we suggest that the NE- and NW-striking pre-existing faults divide the Zhu 3 Depression into different structural zones and controlled the differences in deformation in the basin. The regional stress direction, which is controlled by regional plate interactions and the Red River Fault Zone, changed clockwise from NW-trending during the Paleocene to NE-trending during the Mid-Miocene. These findings will contribute to a better understanding of the evolution of the entire South China Sea.</jats:p> <jats:p content-type="thematic-collection"> <jats:bold>Thematic collection:</jats:bold> This article is part of the Emerging knowledge on the tectonics of the South China Sea collection available at: <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://www.lyellcollection.org/topic/collections/south-china-sea">https://www.lyellcollection.org/topic/collections/south-china-sea</jats:ext-link> </jats:p>

<jats:p> Understanding the long-term variations in seawater sulfate concentrations ([SO <jats:sub>4</jats:sub> <jats:sup>2−</jats:sup> ] <jats:sub>sw</jats:sub> ) is crucial to our understanding of the dynamic relationships between the sulfur, carbon, calcium and oxygen cycles, and their influence on the habitability of the Earth. Here, we explore how [SO <jats:sub>4</jats:sub> <jats:sup>2−</jats:sup> ] <jats:sub>sw</jats:sub> has changed throughout the Phanerozoic and its impact on other elemental cycles. We do this by utilizing the biogeochemical box model GEOCARBSULFOR. The model suggests that [SO <jats:sub>4</jats:sub> <jats:sup>2−</jats:sup> ] <jats:sub>sw</jats:sub> increased throughout the Paleozoic, decreased during the Mesozoic and then increased once more in the Cenozoic, generally matching geochemical proxies. Atmospheric oxygen mirrors [SO <jats:sub>4</jats:sub> <jats:sup>2−</jats:sup> ] <jats:sub>sw</jats:sub> changes during the Paleozoic and Mesozoic, but, intriguingly, decouples during the Cenozoic. We further explored the controls on [SO <jats:sub>4</jats:sub> <jats:sup>2−</jats:sup> ] <jats:sub>sw</jats:sub> by modifying the modelled gypsum fluxes via the incorporation of evaporite data from the geological record. We found that forcing gypsum burial with the observed evaporite deposition data causes the model to better match proxy records at some times, but worsens predictions at others. We also investigated the reliance of the model on a prescribed record of marine calcium concentrations, finding that it is a dominant control on modelled Phanerozoic [SO <jats:sub>4</jats:sub> <jats:sup>2−</jats:sup> ] <jats:sub>sw</jats:sub> and that removing this control seriously degrades the model predictions. We conclude that no model can yet simulate a reasonable evolution of both the calcium and sulfur cycles. </jats:p> <jats:p content-type="supplementary-material"> <jats:bold>Supplementary material:</jats:bold> Figures S1–S5 are available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" specific-use="dataset is-supplemented-by" xlink:href="https://doi.org/10.6084/m9.figshare.c.7164928">https://doi.org/10.6084/m9.figshare.c.7164928</jats:ext-link> </jats:p> <jats:p content-type="thematic-collection"> <jats:bold>Thematic collection:</jats:bold> This article is part of the Sulfur in the Earth system collection available at: <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://www.lyellcollection.org/topic/collections/sulfur-in-the-earth-system">https://www.lyellcollection.org/topic/collections/sulfur-in-the-earth-system</jats:ext-link> </jats:p>

<jats:p> The structures, sedimentary fill and magmatic rocks of sedimentary basins are the products of regional tectonic evolution and are crucial to studying the basin's tectonic–palaeogeographical environment and regional tectonic evolution. The present study discusses the zircon U–Pb dating of volcanic rock samples, <jats:italic>in situ</jats:italic> Hf isotope and whole-rock geochemistry analysis, and the palaeogeographical, sedimentary filling and tectonic background of the Bayingobi basin through outcrop and core descriptions of Meso-Cenozoic strata, stratigraphic correlation and lithofacies analysis. The U–Pb age of the volcanic rocks is 132–102 Ma, and the <jats:italic>in situ</jats:italic> Hf isotopic values range from −20.99 to +29.48. The <jats:sup>87</jats:sup> Sr/ <jats:sup>86</jats:sup> Sr and <jats:sup>143</jats:sup> Nd/ <jats:sup>144</jats:sup> Nd isotopic ratios of the volcanic rocks are 0.707049–0.879761 and 0.511846–0.512540, respectively, and the Nd isotopic values range from −0.62 to −6.83. The volcanic rocks in the basin have the characteristics of continental margin island arc volcanic rocks (CAA) with loss of Nb and Ta and enrichment of Pb, originating mainly from dehydration melting of the subducting plate. The lower Cretaceous Bayingobi, Suhongtu and Yingen Formations developed specifically delta–lacustrine deposits. The lower and upper member of the Bayingobi Formation was deposited in the Berriasian to Valanginian and Valanginian to late Aptian, respectively. The Suhongtu Formation was deposited during the late Aptian to early Albian and was controlled by the strike of the Engeer Us fault. The Yingen Formation was deposited in the late faulted depression stage in the late Albian. Because of the subduction of the Mongol–Okhotsk Ocean plate in the Early Cretaceous, several depressions (sags) were formed in the Bayingobi basin, accompanied by the eruption of continental plate margin island arc magmas. With the closure of the Mongol–Okhotsk Ocean in the late Early Cretaceous, the basin was uplifted as a whole and the Upper Cretaceous Ulansuhai Formation was deposited. </jats:p> <jats:p content-type="supplementary-material"> <jats:bold>Supplementary material</jats:bold> : Supplementary figures and tables are available at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" specific-use="dataset is-supplemented-by" xlink:href="https://doi.org/10.6084/m9.figshare.c.7105807">https://doi.org/10.6084/m9.figshare.c.7105807</jats:ext-link> </jats:p>

<jats:p> Restoring primary depositional frameworks from orogenic settings is challenging. To demonstrate a robust determination of original, but now highly deformed, depositional frameworks and their first-order sequence-stratigraphy, we analyse the Dalradian succession of Tyndrum–Glen Lyon (Breadalbane) in the southwestern Grampian Highlands of Scotland. In Breadalbane, several distinctive Appin and Argyll group Dalradian formations are absent. Omission has been attributed to ductile shearing on the Boundary Slide structure, during the Grampian Orogeny ( <jats:italic>c.</jats:italic> 470 Ma). Alternatively, we restore and describe a primary depositional framework and widely developed intra-Dalradian basin unconformity in Breadalbane, preserved in the relatively low-strain lower limb of the Grampian D <jats:sub>2</jats:sub> Ben Lui Syncline. On this unconformity, locally distinctive strata of the Easdale Subgroup, and more regionally typical strata of the Crinan Subgroup, were deposited directly on strata of the Lochaber Subgroup. Northeastward loss of strata of the Ballachulish, Blair Atholl and Islay subgroups, observed SW of Tyndrum, contrasts with gradual reappearance of correlative units northeastwards from Glen Lyon. Onlap and/or overstep relationships are well preserved; although strain is enhanced locally along pronounced stratal or rheological contrasts, the stratigraphical framework remains essentially intact. Our Scotland-wide analysis of the Dalradian depositional framework recognizes other probable basin-scale unconformities that locally influenced patterns of superimposed orogenic deformation. </jats:p>

<jats:p> Fluvial terraces are important archives for inferring changes in river dynamics. In the NE Tibetan Plateau, the Huangshui River flows through broad depressions and narrow gorges. This morphology is the result of strike-slip and reverse faulting. Differential vertical motion has led to the formation of diverse fluvial terraces. We used morphological analyses, sedimentary successions and optically stimulated luminescence dating to map, characterize and date fluvial terraces in two depressions and the connecting gorge. Our results show that an important phase of tectonism occurred shortly after 138 ka because: (1) terraces older than 138 ka in the gorge show clear deformation in their longitudinal profiles; (2) terraces from the last interglacial are composed of a thick fill terrace in the upstream depression, a strath terrace in the gorge and a fill terrace created by an alluvial fan in the downstream depression; and (3) the aggradation of the last interglacial terrace began synchronously in the upstream and downstream depressions, whereas the abandonment age becomes younger in an upstream direction (from <jats:italic>c.</jats:italic> 131 to <jats:italic>c.</jats:italic> 91 ka). The transient abandonment reflects an upstream-migrating knickpoint. </jats:p> <jats:p content-type="thematic-collection"> <jats:bold>Thematic collection:</jats:bold> This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change">https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change</jats:ext-link> </jats:p>

<jats:p> We investigate in this paper mineral compositions and geochemical evolution of the mantle wedge peridotites preserved in the Late Cretaceous Zagros ophiolites of SW Iran. Mantle peridotites above subduction zones commonly experience distinct melting, depletion and refertilization processes as a result of the circulation of fluids derived from subducting slabs and flux melting. Our results reveal that the mantle wedge peridotites in the Zagros ophiolites are characterized mainly by residual and impregnated types. Residual peridotites resulted from early depletion and later refertilization processes, whereas impregnated peridotites developed due to episodic melt impregnations within and across the mantle. Mg#s and NiO contents, spinel Cr#, Mg#, and TiO <jats:sub>2</jats:sub> in olivines, Mg# and Al <jats:sub>2</jats:sub> O <jats:sub>3</jats:sub> contents of orthopyroxenes, and Mg#, TiO <jats:sub>2</jats:sub> and Al <jats:sub>2</jats:sub> O <jats:sub>3</jats:sub> contents in clinopyroxenes of dunites, harzburgites and lherzolites indicate the significant role of re-equilibration processes among different mineral phases and interactions with basaltic melts percolating within the host peridotites. The observed geochemical variations in the mineral chemistry of the Zagros peridotites reflect changes in magma chemistry and fluctuations in the degree of melt extraction and melt–rock interactions within the mantle peridotites. However, our data suggest that Mg–Fe distribution in the spinels of some dunites and harzburgites might also have resulted from subsolidus redistribution and exchange with surrounding olivine grains. Spinel and clinopyroxene phases in gabbroic rocks and ultramafic cumulates within the Zagros ophiolites also show significant variations in their compositions, suggesting that their magmas evolved from MORB-like to IAT, calc–alkaline and boninite suites, typical of subduction initiation-generated melts. Hence, the Zagros ophiolites present a case study of time-progressive melt evolution of the forearc oceanic lithosphere. </jats:p> <jats:p content-type="supplementary-material"> <jats:bold>Supplementary material:</jats:bold> Datasets of the mineral chemistry and melt evolution of the mantle wedge peridotites in the Late Cretaceous Zagros Belt ophiolites (Iran) are available in tabular and figurative form at <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" specific-use="dataset is-supplemented-by" xlink:href="https://doi.org/10.6084/m9.figshare.c.7093528">https://doi.org/10.6084/m9.figshare.c.7093528</jats:ext-link> . </jats:p> <jats:p content-type="thematic-collection"> <jats:bold>Thematic collection:</jats:bold> This article is part of the Ophiolites, melanges and blueschists collection available at: <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists">https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists</jats:ext-link> </jats:p>