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Tidal dissipation morphodynamic feedback triggers loss of microtidal marshes Geology (IF 5.8) Pub Date : 2024-05-01 Samuel M. Zapp, Giulio Mariotti
Coastal marsh loss is commonly attributed to changes in external forcings, such as an increase in sea-level rise rate or a reduction in sediment supply. Here we show that extensive marsh loss can be caused by internal mechanisms alone, and specifically by autogenic tidal choking. This occurs when the marsh fills in, increasing tidal dissipation by bed friction and eventually decreasing the tidal range
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Hydrologically driven modulation of cutoff regime in meandering rivers Geology (IF 5.8) Pub Date : 2024-05-01 Riccardo Maitan, Alvise Finotello, Davide Tognin, Andrea D'Alpaos, Christopher R. Fielding, Alessandro Ielpi, Massimiliano Ghinassi
Bend cutoff is a fundamental process shaping meandering rivers. Despite the widely accepted differentiation between neck and chute cutoffs, a significant knowledge gap persists regarding the factors responsible for the occurrence of each cutoff regime and the specific conditions triggering the regime. Here, we used field and photogrammetric data derived from a global set of 22 meandering rivers, stretching
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Discovery of modern living intertidal stromatolites on Sheybarah Island, Red Sea, Saudi Arabia Geology (IF 5.8) Pub Date : 2024-05-01 Volker Vahrenkamp, Viswasanthi Chandra, Elisa Garuglieri, Ramona Marasco, Kai Hachmann, Pankaj Khanna, Daniele Daffonchio, Alexander Petrovic
Microbial carbonates, and stromatolites in particular, represent the earliest geological record of life on Earth, which dominated the planet as the sole biotic carbonate factory for almost 3 b.y., from the Archean to the late Proterozoic. Rare and sparsely scattered across the globe in the present day, modern “living” stromatolites are typically relegated to extreme environmental niches, remaining
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Cenozoic Pb–Zn–Ag mineralization in the Western Alps Geology (IF 5.8) Pub Date : 2024-05-01 Maxime Bertauts, Adrien Vezinet, Emilie Janots, Magali Rossi, Isabelle Duhamel-Achin, Philippe Lach, Pierre Lanari
Metallogenic models of polyphase mountain belts critically rely on robust geochronology. We combine petrology with Rb–Sr and U–Th–Pb in situ geochronology, paired at thin-section scale, to date mineralization in deformed hydrothermal Pb–Zn–Ag deposits along an east-west transect in the Western Alps, France. The Pb–Zn–Ag veins occur in shear zones with kinematic structures consistent with the mylonitized
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Tracking cycles of Phanerozoic opening and closing of ocean basins using detrital rutile and zircon geochronology and geochemistry Geology (IF 5.8) Pub Date : 2024-05-01 Margaret L. Odlum, Tomas N. Capaldi, Kelly D. Thomson, Daniel F. Stockli
Sedimentary basins provide a deep time archive of tectonic and Earth-surface processes that can be leveraged by detrital mineral U-Pb dating and geochemistry to track paleogeography, magmatism, and crustal evolution. Zircon preserves the long-term (billions of years) record of supercontinent cycles; however, it is biased toward preserving felsic crustal records. Detrital rutile complements the detrital
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Hydrological fluctuations in the Tarim Basin, northwest China, over the past millennium Geology (IF 5.8) Pub Date : 2024-05-01 Kangkang Li, Xiaoguang Qin, Gill Plunkett, David Brown, Bing Xu, Lei Zhang, Zhaoyan Gu, Guijin Mu, Hongjuan Jia, Zhiqiang Yin, Jiaqi Liu
Reconstruction of hydrological fluctuations in arid regions has proven challenging due to a lack of reliable chronologic constraints on sparse geological archives. The aim of this study was to establish an independent record of hydrologic changes in the hyper-arid Tarim Basin (TB; northwest China) with high spatiotemporal resolution. We present comprehensive radiocarbon and tree-ring data sets of subfossilized
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Submarine volcanism along shallow ridges did not drive Cryogenian cap carbonate formation Geology (IF 5.8) Pub Date : 2024-05-01 Adriana Dutkiewicz, R. Dietmar Müller
The termination of Neoproterozoic “Snowball Earth” glaciations is marked globally by laterally extensive neritic cap carbonates directly overlying glacial diamictites. The formation of these unique deposits on deglaciation calls for anomalously high calcium carbonate saturation. A popular mechanism to account for the source of requisite ocean alkalinity is the shallow-ridge hypothesis, in which initial
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Gibraltar subduction zone is invading the Atlantic Geology (IF 5.8) Pub Date : 2024-05-01 João C. Duarte, Nicolas Riel, Filipe M. Rosas, Anton Popov, Christian Schuler, Boris J.P. Kaus
Subduction initiation is a cornerstone of the Wilson cycle. It marks the turning point in an ocean's lifetime, allowing its lithosphere to be recycled into the mantle. However, formation of new subduction zones in Atlantic-type oceans is challenging, given that it commonly involves the action of an external force, such as the slab pull from a nearby subduction zone, a far-field compression, or the
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Recognizing big mantle wedges in deep time: Constraints from the Western Mongolia Collage in Central Asia Geology (IF 5.8) Pub Date : 2024-05-01 Xing Cui, Peter A. Cawood, Min Sun, Guochun Zhao
A big mantle wedge (BMW) is defined as the broad region of upper mantle above a stagnant slab in the mantle transition zone (MTZ). It is a common and significant structure within Earth's interior at modern convergent plate margins as revealed by seismic data yet rarely identified in fossil convergent systems. We propose the existence of a BMW beneath the Western Mongolia Collage during the early to
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Reconciling plate motion and faulting at a rift-rift-rift triple junction Geology (IF 5.8) Pub Date : 2024-05-01 Daniele Maestrelli, Federico Sani, Derek Keir, Carolina Pagli, Alessandro La Rosa, Ameha Atnafu Muluneh, Sascha Brune, Giacomo Corti
Rift-Rift-Rift triple junctions are regions where three plates interact, generating complex networks of variably oriented faults. While the geometry of the fault networks is easily constrained from their surface expression, what remains unclear is how the kinematics of faults and their interactions vary spatially, and how these relate to the unusual crustal motions that result from three plates diverging
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Long-lived Northern Hemisphere convergence systems driven by upper-mantle thermal inhomogeneity Geology (IF 5.8) Pub Date : 2024-05-01 Liang Liu, Zebin Cao, Jason P. Morgan, Hong-Yan Li, Fan Yang, Yi-Gang Xu
Plate reconstructions reveal that two secular centers of convergence formed beneath eastern Eurasia and North America no later than 200 Ma. The cause of these convergence centers, which featured flat subduction, slab stagnation, and/or continental margin subduction, remains uncertain. Here, we propose that upper-mantle thermal inhomogeneity, particularly an anomalously cool Northern Hemispheric upper
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Strong seismic anisotropy due to upwelling flow at the root of the Yellowstone mantle plume Geology (IF 5.8) Pub Date : 2024-05-01 Jonathan Wolf, Mingming Li, Anne A. Haws, Maureen D. Long
The Yellowstone region (western United States) is a commonly cited example of intraplate volcanism whose origin has been a topic of debate for several decades. Recent work has suggested that a deep mantle plume, rooted beneath southern California, is the source of Yellowstone volcanism. Seismic anisotropy, which typically results from deformation, can be used to identify and characterize mantle flow
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Fluvial response to Late Pleistocene–Holocene climate change in the Colorado River drainage, central Texas, USA: COMMENT Geology (IF 5.8) Pub Date : 2024-05-01 Mike Blum, Dustin Sweet
Abstract not available
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Fluvial response to Late Pleistocene–Holocene climate change in the Colorado River drainage, central Texas, USA: REPLY Geology (IF 5.8) Pub Date : 2024-05-01 E. Gabriela Gutiérrez, Daniel F. Stockli
Abstract not available
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Life in the Cambrian shallows: Exceptionally preserved arthropod and mollusk microfossils from the early Cambrian of Sweden Geology (IF 5.8) Pub Date : 2024-04-01 Ben J. Slater
Burgess Shale–type (BST) Lagerstätten record an exceptional variety of Cambrian soft-bodied fauna, yet these deposits are typically restricted to outboard depositional settings >1000 km from the paleocoastline. For shallow, well-oxygenated shelf environments, our knowledge of non-mineralized animals (the majority of diversity) is severely limited, giving rise to substantial bias in our perception of
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Does zircon geochemistry record global sediment subduction? Geology (IF 5.8) Pub Date : 2024-04-01 Kurt E. Sundell, Francis A. Macdonald, Stephen J. Puetz
Global compilations of zircon geochemistry have been used as evidence for changes in plate tectonic styles and surface environments. In particular, zircon δ18O has been used as a proxy for global sediment subduction and incorporation into igneous melts. However, research employing such compilations commonly ignores geologic and geographic context. We analyze a newly georeferenced zircon δ18O database
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Subduction polarity reversal facilitated by plate coupling during arc-continent collision: Evidence from the Western Kunlun orogenic belt, northwest Tibetan Plateau Geology (IF 5.8) Pub Date : 2024-04-01 Zaili Tao, Jiyuan Yin, Christopher J. Spencer, Min Sun, Wenjiao Xiao, Andrew C. Kerr, Tao Wang, Pengpeng Huangfu, Yunchuan Zeng, Wen Chen
Subduction polarity reversal usually involves the break off or tearing of the downgoing plate (DP) along the continent-ocean transition zone, in order to initiate subduction of the overriding plate (OP) with opposite polarity. We propose that subduction polarity reversal can also be caused by DP-OP coupling and can account for the early Paleozoic geological relationships in the Western Kunlun orogenic
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Ice-rafted dropstones at midlatitudes in the Cretaceous of continental, Iberia: REPLY Geology (IF 5.8) Pub Date : 2024-04-01 Juan Pedro Rodríguez-López, Carlos L. Liesa, Aránzazu Luzón, Arsenio Muñoz, María J. Mayayo, Julian B. Murton, Ana R. Soria
Abstract not available
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Geoelectric evidence for a wide spatial footprint of active extension in central Colorado Geology (IF 5.8) Pub Date : 2024-04-01 Benjamin S. Murphy, Jonathan Saul Caine, Paul A. Bedrosian, Jade W. Crosbie
Three-dimensional magnetotelluric (MT) imaging in central Colorado reveals a set of north-striking high-conductivity tracks at lower-crustal (50–20 km) depths, with conductive finger-like structures rising off these tracks into the middle crust (20–5 km depth). We interpret these features to represent saline aqueous fluids and partial melt that are products of active extensional tectonomagmatism. These
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Resolving pressure differences within the Grand Canyon Precambrian basement: Implications for Proterozoic tectonics Geology (IF 5.8) Pub Date : 2024-04-01 Suzanne Autrey-Mulligan, Chloe Bonamici, Michael L. Williams, Karl Karlstrom, Cailey B. Condit
Burial pressures (depths) within mountain belts place fundamental constraints on the growth and stabilization of continental crust. We report precise metamorphic pressures for ca. 1.7 Ga rocks from the Upper Granite Gorge (UGG) of the Grand Canyon (southwestern United States) and, for the first time, resolve pressure variations across this continuous exposure of mid-crustal rocks. We applied quartz-in-garnet
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Iron fertilization–induced deoxygenation of eastern equatorial Pacific Ocean intermediate waters during the Paleocene–Eocene thermal maximum Geology (IF 5.8) Pub Date : 2024-04-01 Xiaodong Jiang, Xiangyu Zhao, Xiaoming Sun, Andrew P. Roberts, Appy Sluijs, Yu-Min Chou, Weiqi Yao, Jieqi Xing, Weijie Zhang, Qingsong Liu
The Paleocene–Eocene thermal maximum (PETM), a transient period of global warming, is considered to be an important analog for future greenhouse conditions. It was accompanied by a significant carbon cycle perturbation. Although ocean deoxygenation across the PETM is reported widely, its mechanism in the open ocean remains uncertain. Here, we present magnetic and geochemical analyses of sediments from
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Rare earth element transport and mineralization linked to fluids from carbonatite systems Geology (IF 5.8) Pub Date : 2024-04-01 E.A.A. Mororó, M. Berkesi, Z. Zajacz, T. Guzmics
Rare earth elements are critical constituents for modern technologies, and some of their largest natural resource deposits are related to carbonatite systems. However, the mechanisms leading to rare earth element mineralization and the role of magmatic fluids in carbonatite systems remain poorly understood. Here, we present the first in situ characterization of fluids and their trace-element compositions
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Duration of Sturtian “Snowball Earth” glaciation linked to exceptionally low mid-ocean ridge outgassing Geology (IF 5.8) Pub Date : 2024-04-01 Adriana Dutkiewicz, Andrew S. Merdith, Alan S. Collins, Ben Mather, Lauren Ilano, Sabin Zahirovic, R. Dietmar Müller
The Sturtian “Snowball Earth” glaciation (ca. 717–661 Ma) is regarded as the most extreme interval of icehouse climate in Earth’s history. The exact trigger and sustention mechanisms for this long-lived global glaciation remain obscure. The most widely debated causes are silicate weathering of the ca. 718 Ma Franklin large igneous province (LIP) and changes in the length and degassing of continental
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Mantle flow and olivine fabric transition in the Myanmar continental subduction zone Geology (IF 5.8) Pub Date : 2024-04-01 Enbo Fan, Yinshuang Ai, Stephen S. Gao, Yumei He, Kelly H. Liu, Mingming Jiang, Guangbing Hou, Shun Yang, Chit Thet Mon, Myo Thant, Kyaing Sein
One of the major advances in mineral physics and seismology is the realization that different olivine fabric types are functions of temperature, shear stress, and water content in oceanic subducting systems. The distribution of different olivine fabric types and geodynamic processes in the mantle wedge above a subducting continental slab remain poorly understood. Here, based on splitting analysis of
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Nannofossil imprints across the Paleocene–Eocene thermal maximum Geology (IF 5.8) Pub Date : 2024-04-01 Sam M. Slater, Paul R. Bown, Phillip E. Jardine
The Paleocene–Eocene thermal maximum (PETM; ca. 56 Ma) geological interval records a marked decline in calcium carbonate (CaCO3) in seafloor sediments, potentially reflecting an episode of deep- and possibly shallow-water ocean acidification. However, because CaCO3 is susceptible to postburial dissolution, the extent to which this process has influenced the PETM geological record remains uncertain
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Increase in magma supply to Sakurajima volcano’s (Japan) shallow magma chamber over the past 500 years Geology (IF 5.8) Pub Date : 2024-04-01 Christian Huber, Atsushi Toramaru
Constraining the magma supply to a subvolcanic reservoir is crucial to characterizing unrest and evaluating the potential for a forthcoming eruption. With the advent of GPS, tiltmeters, and satellite interferometry, it has been possible to infer changes in the supply rate of magma to shallow reservoirs over time scales of as much as decades. While these methods have impacted our ability to characterize
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Bulldoze and rebuild: Modifying cratonic lithosphere via removal and replacement induced by continental subduction Geology (IF 5.8) Pub Date : 2024-04-01 Lingtong Meng, Yang Chu, Wei Lin, Ross N. Mitchell, Liang Zhao
Establishing the mechanisms for craton modification is critical for understanding cratonic stability and architecture. It is well known that oceanic subduction and mantle plumes can destroy and destabilize the overriding cratonic lithosphere, but the role of continental subduction in craton modification remains unclear. In the North China craton (NCC), which experienced deep continental subduction
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A late refugium for Classopollis in the Paleocene Lower Wilcox Group along the Texas Gulf Coast Geology (IF 5.8) Pub Date : 2024-04-01 Vann Smith, Angela Hessler, Lorena Moscardelli, David Bord, Iulia Olariu, Maria Antonieta Lorente, Evan Sivil, Xiuju Liu
We report a new ecological refugium for the Cheirolepidiaceae family (pollen form genus Classopollis) in the Paleocene Lower Wilcox Group in the Gulf Coast of southeastern Texas based on palynological analysis of four wells. The Cheirolepidiaceae were once thought to have gone extinct at the Cretaceous–Paleogene (K/Pg) boundary or earlier in North America; however, similar ecological refugia for this
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Precambrian to Pleistocene 40Ar/39Ar dating of clinopyroxene-hosted melt inclusions Geology (IF 5.8) Pub Date : 2024-04-01 Brian R. Jicha, Allen J. Schaen, Bryan Wathen, William O. Nachlas
Clinopyroxene is a rock-forming mineral that commonly hosts melt inclusions in mafic to intermediate composition volcanic and plutonic rocks. It is highly resistant to alteration compared to other co-existing phenocrysts such as plagioclase. Several recent studies have 40Ar/39Ar dated clinopyroxene in Neoproterozoic to Miocene basalts and dolerites. To assess the viability of the technique at the youngest
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Intersection between tectonic faults and magmatic systems promotes swarms with large-magnitude earthquakes around the Tengchong volcanic field, southeastern Tibetan Plateau Geology (IF 5.8) Pub Date : 2024-04-01 Min Liu, Yen Joe Tan, Xinglin Lei, Hongyi Li, Yunpeng Zhang, Weitao Wang
Volcanic regions commonly host swarms comprising small to moderate-sized earthquakes while tectonic faults host mostly mainshock-aftershock sequences that can include very large earthquakes. In the southeastern Tibetan Plateau, large tectonic faults formed by the collision between the Indian and Eurasian plates intersect with the intraplate Tengchong volcanic field, and the seismic behavior of such
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Correlating mantle cooling with tectonic transitions on early Earth Geology (IF 5.8) Pub Date : 2024-04-01 Prasanna M. Gunawardana, Priyadarshi Chowdhury, Gabriele Morra, Peter A. Cawood
The dominant tectonic mode operating on early Earth (before ca. 2.5 Ga) remains elusive, with an increasing body of evidence suggesting that non-plate tectonic modes were likely more prevalent at that time. Thus, how plate tectonics evolved after that remains contentious. We performed two-dimensional numerical modeling of mantle convection at temperatures appropriate for the Hadean–Archean eons and
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Rapid development of spiral garnets during subduction zone metamorphism revealed from high-resolution Sm-Nd garnet geochronology Geology (IF 5.8) Pub Date : 2024-04-01 Thomas P. Farrell, Domingo Aerden, Ethan F. Baxter, Paul G. Starr, Mike L. Williams
Multiple studies have applied zoned garnet geochronology to place temporal constraints on the rates of metamorphism and deformation during orogenesis. We report new high-resolution isotope dilution–thermal ionization mass spectrometry Sm-Nd isochron ages on concentric growth zones from microstructurally and thermodynamically characterized garnets from the Betic Cordillera, southern Spain. Our ages
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Initiation of the Cascade arc Geology (IF 5.8) Pub Date : 2024-04-01 Jeffrey H. Tepper, Kenneth P. Clark
The Cascade arc (western North America) is the world’s youngest continental arc, and because the down-going Juan de Fuca plate is young, it is also the hottest end member among subduction zones worldwide. We present evidence that the arc initiated <5 m.y. after accretion of the Siletzia oceanic terrane terminated the earlier subduction system and caused the northern portion of the Farallon slab to
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Ice-rafted dropstones at midlatitudes in the Cretaceous of continental Iberia: COMMENT Geology (IF 5.8) Pub Date : 2024-04-01 M. Isabel Benito, I. Emma Quijada, Martín Garcia-Martín, Alejandro Pertuz, Pablo Suarez-Gonzalez, Angélica Torices, Sonia Campos-Soto
Abstract not available
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Constraints of boron and oxygen stable isotopes on dehydration fluids, sediment-derived melts, and crustal assimilation of the Toba volcanic system (Indonesia) Geology (IF 5.8) Pub Date : 2024-03-01 Ping-Ping Liu, Dian-Bing Wang, Mei-Fu Zhou, Xian-Hua Li, Qiu-Li Li, Glenn A. Gaetani, Brian Monteleone, Vadim Kamenetsky
Arc magmas are produced from the mantle wedge, with possible addition of fluids and melts derived from serpentinites and sediments in the subducting slab. Identification of various sources and their relevant contributions to such magmas is challenging; in particular, at continental arcs where crustal assimilation may overprint initial geochemical signatures. This study presents oxygen isotopic compositions
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An Eoarchean continental nucleus for the Fennoscandian Shield and a link to the North Atlantic craton Geology (IF 5.8) Pub Date : 2024-03-01 Andreas Petersson, Tod Waight, Anthony I.S. Kemp, Martin. J. Whitehouse, John W. Valley
Enabling the build-up of continental crust is a vital step in the stabilization of cratonic lithosphere. However, these initial crustal nuclei are commonly either destroyed by recycling or buried by younger rocks. In the Fennoscandian Shield, the oldest rocks are ca. 3.5 Ga, but ca. 3.7 Ga inherited and detrital zircons suggest the presence of an older, unexposed crustal substrate. We present U-Pb
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Discovery of Permian–Triassic eclogite in northern Tibet establishes coeval subduction erosion along an ~3000-km-long arc: COMMENT Geology (IF 5.8) Pub Date : 2024-03-01 Shuguang Song, Hafiz U. Rehman
Abstract not available
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Boninitic melt percolation makes depleted mantle wedges rich in silica: COMMENT Geology (IF 5.8) Pub Date : 2024-03-01 Antoine Bénard, Dmitri A. Ionov, Oliver Nebel, Richard J. Arculus
Abstract not available
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Boninitic melt percolation makes depleted mantle wedges rich in silica: REPLY Geology (IF 5.8) Pub Date : 2024-03-01 Ming Chen, Jianping Zheng, Hong-Kun Dai, Qing Xiong, Min Sun, Mikhail M. Buslov, Xiang Zhou, Jingao Liu
Abstract not available
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Discovery of Permian–Triassic eclogite in northern Tibet establishes coeval subduction erosion along an ~3000-km-long arc: REPLY Geology (IF 5.8) Pub Date : 2024-03-01 Chen Wu, Andrew V. Zuza, Drew A. Levy, Jie Li, Lin Ding
Abstract not available
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Elastic stresses can form metamorphic fabrics Geology (IF 5.8) Pub Date : 2024-03-01 James Gilgannon, Damien Freitas, Roberto Emanuele Rizzo, John Wheeler, Ian B. Butler, Sohan Seth, Federica Marone, Christian M. Schlepütz, Gina McGill, Ian Watt, Oliver Plümper, Lisa Eberhard, Hamed Amiri, Alireza Chogani, Florian Fusseis
Detailing the relationship between stress and reactions in metamorphic rocks has been controversial, and much of the debate has centered on theory. Here, we add to this discussion and make a major advance by showing in time-resolved synchrotron microtomography experiments that a reacting and deforming sample experiencing an elastic differential stress produces a fabric orthogonal to the largest principal
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Toroidal flow around the Tonga slab moved the Samoan plume during the Pliocene Geology (IF 5.8) Pub Date : 2024-03-01 Kevin Konrad, Matthew Jackson, Bernhard Steinberger, Anthony Koppers, Andrea Balbas, Valerie Finlayson, Jasper Konter, Allison Price
Age-progressive seamount tracks generated by lithospheric motion over a stationary mantle plume have long been used to reconstruct absolute plate motion (APM) models. However, the basis of these models requires the plumes to move significantly slower than the overriding lithosphere. When a plume interacts with a convergent or divergent plate boundary, it is often deflected within the strong local mantle
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Mechanisms of nitrogen isotope fractionation at an ancient black smoker in the 2.7 Ga Abitibi greenstone belt, Canada Geology (IF 5.8) Pub Date : 2024-03-01 A.N. Martin, E.E. Stüeken, J.A.-S. Michaud, C. Münker, S. Weyer, E.H.P. van Hees, M.M. Gehringer
The biological nitrogen (N) cycle on early Earth is enigmatic because of limited data from Archean (meta-)sediments and the potential alteration of primary biotic signatures. Here we further investigate unusual 15N enrichments reported in 2.7 Ga meta-sediments from the Abitibi greenstone belt, Canada, purportedly related to a 15N-enriched Archean atmosphere. Given that sediments from this region are
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Methane-carbon budget of a ferruginous meromictic lake and implications for marine methane dynamics on early Earth Geology (IF 5.8) Pub Date : 2024-03-01 Sajjad A. Akam, Pei-Chuan Chuang, Sergei Katsev, Chad Wittkop, Michelle Chamberlain, Andrew W. Dale, Klaus Wallmann, Adam J. Heathcote, Elizabeth D. Swanner
The greenhouse gas methane (CH4) contributed to a warm climate that maintained liquid water and sustained Earth’s habitability in the Precambrian despite the faint young sun. The viability of methanogenesis (ME) in ferruginous environments, however, is debated, as iron reduction can potentially outcompete ME as a pathway of organic carbon remineralization (OCR). Here, we document that ME is a dominant
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High-precision U-Pb geochronology links magmatism in the Southwestern Laurentia large igneous province and Midcontinent Rift Geology (IF 5.8) Pub Date : 2024-03-01 M.T. Mohr, M.D. Schmitz, N.L. Swanson-Hysell, K.E. Karlstrom, F.A. Macdonald, M.E. Holland, Y. Zhang, N.S. Anderson
The Southwestern Laurentia large igneous province (SWLLIP) comprises voluminous, widespread ca 1.1 Ga magmatism in the southwestern United States and northern Mexico. The timing and tempo of SWLLIP magmatism and its relationship to other late Mesoproterozoic igneous provinces have been unclear due to difficulties in dating mafic rocks at high precision. New precise U-Pb zircon dates for comagmatic
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Crucial role of water-present melting in metagranite: Implications for the instigation of crustal-scale shear zones Geology (IF 5.8) Pub Date : 2024-03-01 Jonas Vanardois, Pierre Trap, Didier Marquer
Where, when, and why large-scale shear zones nucleate and propagate into the continental lithosphere are critical issues that challenge the research in tectonics. The East Variscan shear zone is one of the crustal-scale strike-slip faults that shaped the Variscan orogenic crust during late Carboniferous time. Field-based structural analysis and petrological observations demonstrate that suprasolidus
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A Bayesian astrochronology for the Cambrian first occurrence of trilobites in West Gondwana (Morocco) Geology (IF 5.8) Pub Date : 2024-03-01 Matthias Sinnesael, Andrew R. Millard, Martin R. Smith
The first occurrence of trilobites at ca. 520 Ma is an iconic feature of the Cambrian Explosion. Developing a robust evolutionary view on early Cambrian life is generally hindered by large uncertainties in the ages of fossil finds and their global stratigraphic correlation. We developed an astrochronological interpretation for the Tiout section in Morocco that features some of the oldest trilobite
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From dome to duplex: Convergent gravitational collapse explains coeval intracratonic doming and nappe tectonics, central Australia Geology (IF 5.8) Pub Date : 2024-03-01 Youseph Ibrahim, Patrice F. Rey, Donna L. Whitney, Christian Teyssier, Françoise Roger, Valérie Bosse, Bénédicte Cenki
In central Australia, an apparently coeval gneiss dome (Entia Dome) developed adjacent to a thrust belt (Arltunga Nappe Complex) within an intracratonic setting. Here we employ a combination of fieldwork, geochronology, and numerical modeling to investigate the structure and tectonic evolution of these features. We present a structural model linking an extensional domain comprising the Entia Dome,
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In situ U-Pb dating of Jurassic dinosaur bones from Sichuan Basin, South China Geology (IF 5.8) Pub Date : 2024-03-01 Liang Qi, Mingcai Hou, Jacob A. Mulder, Peter A. Cawood, Yao Guo, Shitou Wu, Liangxuan Jiao, Xiaolin Zhang, Hui Ouyang
Direct dating of vertebrate fossils is difficult due to complex postburial diagenetic processes and the often low and heterogeneous concentration of radioisotopes (e.g., U) in fossilized bone material. Here, we demonstrate a novel approach to dating vertebrate fossils via laser ablation–inductively coupled plasma–mass spectrometry U-Pb dating of early diagenetic calcite cements precipitated within
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Marine snowstorm during the Permian–Triassic mass extinction Geology (IF 5.8) Pub Date : 2024-02-01 Stephen E. Grasby, Omid H. Ardakani, Xiaojun Liu, David P.G. Bond, Paul B. Wignall, Lorna J. Strachan
The Permian–Triassic mass extinction (PTME) interval is marked by major excursions in both inorganic and organic carbon (C) isotopes. Carbon cycle models predict that these trends were driven by large increases in productivity, yet organic C–rich rocks are not recorded in most PTME shelf sedimentary successions. Anomalous C-rich facies have been reported from rare abyssal plains records now exposed
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Garnet versus amphibole: Implications for magmatic differentiation and slab melting Geology (IF 5.8) Pub Date : 2024-02-01 Yajie Gao, Hugh St. C. O’Neill, John A. Mavrogenes
The garnet signature in the rare earth element (REE) abundances in adakites has been considered a key genetic indicator of these controversial rocks, whose proposed origins include direct melting of subducted oceanic crust (“slab melts”). We show that the garnet signature may be quantified using the shape coefficients of chondrite-normalized REE patterns. We applied this method to a global data set
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Magma-carbonate interactions drive CO2 production and metal enrichment in shallow dikes and sills at volcanic arcs Geology (IF 5.8) Pub Date : 2024-02-01 R.A. Morris, D. Canil, J. Spence
The contribution of CO2 from crustal carbonates into arc magmas is debated, as is its role in the long-term C cycle. To better understand the contributions and mechanisms that drive CO2 production in arc magmas, we examined in detail basaltic dike and sill contacts with carbonate in the Jurassic Bonanza arc on Vancouver Island, Canada. We discovered discrete boundary melts that formed along dike and
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Pleistocene Colorado River terraces in the canyonlands region (Utah, USA) record unsteady, transient incision and growth of the Cataract Canyon knickzone by salt tectonics Geology (IF 5.8) Pub Date : 2024-02-01 Natalie M. Tanski, Joel L. Pederson, Tammy M. Rittenour, Alan J. Hidy
Colorado River terraces in the canyonlands region of southeastern Utah can be dated and analyzed to address the controls of incision and nature of the Colorado Plateau’s largest channel-steepness anomaly, Cataract Canyon. Field correlations supported by luminescence and cosmogenic-nuclide ages on strath terraces along Meander Canyon, upstream of Cataract Canyon, reveal a complex record of unsteady
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Massive rare earth element storage in sub-continental lithospheric mantle initiated by diapirism, not by melting Geology (IF 5.8) Pub Date : 2024-02-01 XinXiang Zhu, Yan Liu, Zengqian Hou
Rare earth elements (REEs) are essential metals for modern technologies. Recent studies suggest that subcontinental lithospheric mantle (SCLM) remelting, previously fertilized by subducted marine sediments, leads to formation of REE-bearing rocks. However, the transfer mechanism of REE-rich sediments from the subducted slab to the overlying mantle wedge is unclear. We present high-pressure experiments
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Intrusion tip velocity controls the emplacement mechanism of sheet intrusions Geology (IF 5.8) Pub Date : 2024-02-01 Jonas Köpping, Alexander R. Cruden, Samuel T. Thiele, Craig Magee, Andrew Bunger
Space for intruding magma is created by elastic, viscous, and/or plastic deformation of host rocks. Such deformation impacts the geometries of igneous intrusions, particularly sills and dikes. For example, tapered intrusion tips indicate linear-elastic fracturing during emplacement, whereas fluidization of host rocks has been linked to development of elongate magma fingers with rounded tips. Although
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Metasomatized mantle sources for orogenic gold deposits hosted in high-grade metamorphic rocks: Evidence from Hg isotopes Geology (IF 5.8) Pub Date : 2024-02-01 Qingfei Wang, Xuefei Liu, Runsheng Yin, Weijun Weng, Hesen Zhao, Lin Yang, Degao Zhai, Dapeng Li, Yao Ma, David I. Groves, Jun Deng
Investigation of Hg isotope ratios of gold-related sulfides and penecontemporaneous mafic dikes from four orogenic gold provinces on the margins of the North China Craton and Yangtze Craton identifies three orogenic gold deposit (OGD) groups from different tectonic regimes. Ore-related sulfides of group 1 OGDs and mafic dikes from the craton margin reworked via oceanic subduction mostly have positive
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Early Cambrian Cambroclavus is a scleritomous eumetazoan unrelated to bryozoan or dasyclad algae Geology (IF 5.8) Pub Date : 2024-02-01 Kai Xiang, Zongjun Yin, Wei Liu, Fangchen Zhao, Maoyan Zhu
The origin of Bryozoa has long been an intriguing mystery, largely due to the dearth of unambiguous bryozoan fossils within Cambrian strata. The earliest bryozoan thus far identified, Protomelission, an early Cambrian microfossil from Australia and China, was recently contested and proposed to be dasyclad algae. Our reanalysis of micro-computed tomography data from Protomelission specimens, however
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Geochemical mapping of lithospheric architecture disproves Archean terrane accretion in the Yilgarn craton Geology (IF 5.8) Pub Date : 2024-02-01 R.H. Smithies, K. Gessner, Y. Lu, C.L. Kirkland, T. Ivanic, J.R. Lowrey, D.C. Champion, J. Sapkota, Q. Masurel, N. Thébaud, R. Quentin de Gromard
The basement of Mesoarchean to Neoarchean greenstone basins in the Yilgarn craton is composed of fragments of evolved crust up to 3.7 Ga old. New cratonwide geochemical and isotopic data with unparalleled spatial resolution image a NE- to ENE-trending architecture in pre–2.73 Ga crust. These trends cannot be reconciled with plate-tectonic models, as they persist across younger NNW-striking structural
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Holocene gigascale rock avalanches in Vaigat strait, West Greenland—Implications for geohazard Geology (IF 5.8) Pub Date : 2024-02-01 Kristian Svennevig, Matthew J. Owen, Michele Citterio, Tove Nielsen, Salik Rosing, Jan Harff, Rudolf Endler, Mathieu Morlighem, Eric Rignot
Rock avalanche–triggered displacement waves (also termed tsunamis) have recently occurred in Greenland and Alaska, and they illustrate the presence of such hazards in polar regions. To improve understanding of the magnitude of this hazard for these areas, we investigated gigascale subaerial rock avalanches impacting a partially confined water body within the Vaigat strait (western Greenland). We present
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Controls on topography and erosion of the north-central Andes Geology (IF 5.8) Pub Date : 2024-02-01 Joel S. Leonard, Kelin X. Whipple, Arjun M. Heimsath
We present 17 new 10Be erosion rates from southern Peru sampled across an extreme orographic rainfall gradient. Using a rainfall-weighted variant of the normalized channel steepness index, ksnQ, we show that channel steepness values, and thus topography, are adjusted to spatially varying rainfall. Rocks with similar physical characteristics define distinct relationships between ksnQ and erosion rate