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Biogeodynamics: Coupled evolution of the biosphere, atmosphere, and lithosphere Geology (IF 6.324) Pub Date : 2022-08-01 Christopher J. Spencer
There is broad consensus that tectonic and magmatic processes play a role in the evolution of life and the composition of the atmosphere. Tectonic and magmatic processes provide a suite of bio-essential nutrients that are carried into the hydrosphere through sedimentary processes. Tectonic processes facilitate the subsequent recycling and concentration of these nutrients for continued biospheric utilization
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Time scales of open-system processes in a complex and heterogeneous mush-dominated plumbing system Geology (IF 6.324) Pub Date : 2022-08-01 Helena Albert, Teresa Trua, José Fonseca, Michael P. Marani, Fabiano Gamberi, Richard Spiess, Andrea Marzoli
The architecture of a mush-dominated plumbing system in active volcanic areas conditions the magma pathways feeding eruptions. Open-system processes along these pathways and the associated time scales are directly related to monitoring data and eruptive behavior. Despite crystal mush–dominated systems being common in active volcanoes, previous studies have not focused on the integration of data from
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Possible bipolar global expression of the P3 and P4 glacial events of eastern Australia in the Northern Hemisphere: Marine diamictites and glendonites from the middle to upper Permian in southern Verkhoyanie, Siberia Geology (IF 6.324) Pub Date : 2022-08-01 V.I. Davydov, I.V. Budnikov, R.V. Kutygin, N.G. Nurgalieva, A.S. Biakov, E.V. Karasev, A.N. Kilyasov, V.I. Makoshin
Three intervals of glaciomarine diamictites with extensive glendonites in middle to upper Permian sediments were found in the Kobyume River, southern Verkhoyanie, Russia. The successions are biostratigraphically constrained as middle to upper Permian. The middle Permian diamictite horizons extend over a large area with a lateral distance of >1000 km. The upper Permian diamictites developed only locally
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Late glacial–Holocene record of Southern Hemisphere westerly wind dynamics from the Falkland Islands, South Atlantic Ocean Geology (IF 6.324) Pub Date : 2022-08-01 Alistair Monteath, Paul Hughes, Matthew Cooper, Dulcinea Groff, Rob Scaife, Dominic Hodgson
The Southern Hemisphere westerly wind belt (SHWW) is a major feature of Southern Hemisphere, midlatitude climate that is closely linked with the sequestration and release of CO2 in the Southern Ocean. Past changes in the strength and position of this wind belt are poorly resolved, particularly across the Pleistocene-Holocene transition, a time period associated with fluctuations in atmospheric temperatures
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Nd isotopic evidence for enhanced mafic weathering leading to Ordovician cooling Geology (IF 6.324) Pub Date : 2022-08-01 Christopher T. Conwell, Matthew R. Saltzman, Cole T. Edwards, Elizabeth M. Griffith, Y. Datu Adiatma
It remains unclear whether waning of the volcanic degassing CO2 source or enhancement of the mafic (Ca, Mg-silicate) weathering CO2 sink, or both, caused global cooling leading to the Ordovician greenhouse–icehouse transition. We present a uniquely age-constrained and integrated Middle–Late Ordovician (470–450 Ma) continental weathering isotopic proxy data set (87Sr/86Sr and εNd(t)) from carbonate
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Thermal and compositional anomalies in a detailed xenolith-based lithospheric mantle profile of the Siberian craton and the origin of seismic midlithosphere discontinuities Geology (IF 6.324) Pub Date : 2022-08-01 Zhe Liu, Dmitri A. Ionov, Paolo Nimis, Yigang Xu, Pengli He, Alexander V. Golovin
The fine structure and thermal state of >200-km-thick cratonic lithosphere remain poorly explored because of insufficient sampling and uncertainties in pressure (P) and temperature (T) estimates. We report exceptionally detailed thermal and compositional profiles of the continental lithospheric mantle (CLM) in the Siberian craton based on petrographic, in situ chemical, and P-T data for 92 new garnet
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Claspers in the mid-Cambrian Olenoides serratus indicate horseshoe crab–like mating in trilobites Geology (IF 6.324) Pub Date : 2022-08-01 Sarah R. Losso, Javier Ortega-Hernández
Sexual reproduction represents a fundamental aspect of animal biology, but the diversity of reproductive strategies among early Paleozoic metazoans remains obscure. Direct evidence of reproductive strategies comes from exceptionally preserved egg masses in Cambrian and Ordovician euarthropods such as waptiids and trilobites, but anatomical or behavioral adaptations for mating in these taxa are all
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Multiple phyla, one time resolution? Similar time averaging in benthic foraminifera, mollusk, echinoid, crustacean, and otolith fossil assemblages Geology (IF 6.324) Pub Date : 2022-08-01 Rafał Nawrot, Michaela Berensmeier, Ivo Gallmetzer, Alexandra Haselmair, Adam Tomašových, Martin Zuschin
Time averaging of fossil assemblages determines temporal precision of paleoecological and geochronological inferences. Taxonomic differences in intrinsic skeletal durability are expected to produce temporal mismatch between co-occurring species, but the importance of this effect is difficult to assess due to lack of direct estimates of time averaging for many higher taxa. Moreover, burial below the
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Evidence for benthic oxygen production in Neoarchean lacustrine stromatolites Geology (IF 6.324) Pub Date : 2022-08-01 Dylan T. Wilmeth, Stefan V. Lalonde, William M. Berelson, Victoria Petryshyn, Aaron J. Celestian, Nicolas J. Beukes, Stanley M. Awramik, John R. Spear, Taleen Mahseredjian, Frank A. Corsetti
The evolution of oxygenic photosynthesis fundamentally altered the global environment, but the history of this metabolism prior to the Great Oxidation Event (GOE) at ca. 2.4 Ga remains unclear. Increasing evidence suggests that non-marine microbial mats served as localized “oxygen oases” for hundreds of millions of years before the GOE, though direct examination of redox proxies in Archean lacustrine
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Cenozoic delamination of the southwestern Yangtze craton owing to densification during subduction and collision Geology (IF 6.324) Pub Date : 2022-08-01 Jun Wang, Qiang Wang, Chuan-Bing Xu, Wei Dan, Zhuo Xiao, Chutian Shu, Gangjian Wei
It is widely thought that oceanic subduction can trigger cratonic keel delamination, but the southwestern Yangtze craton (SYC; southwestern China) lost its lower keel during Cenozoic continental collision. The upper mantle beneath the thinned SYC contains its incompletely delaminated keel, which has high-velocity seismic anomalies. Combining geophysical observations with the geochemistry of Eocene
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830-million-year-old microorganisms in primary fluid inclusions in halite Geology (IF 6.324) Pub Date : 2022-08-01 Sara I. Schreder-Gomes, Kathleen C. Benison, Jeremiah A. Bernau
Primary fluid inclusions in bedded halite from the 830-m.y.-old Browne Formation of central Australia contain organic solids and liquids, as documented with transmitted light and ultraviolet–visible (UV-vis) petrography. These objects are consistent in size, shape, and fluorescent response with cells of prokaryotes and eukaryotes and with organic compounds. This discovery shows that microorganisms
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The influence of glacial isostatic adjustment on continental shelf stratigraphic correlation Geology (IF 6.324) Pub Date : 2022-08-01 Meghan E. King, Jessica R. Creveling
Glacial isostatic adjustment (GIA) imparts geographic variability in the amplitude and timing of local sea-level (LSL) change arising from glacial-interglacial oscillations relative to a global mean signal (eustasy). We modeled how GIA manifests in the stratigraphic record across four shelf-perpendicular transects moving progressively more distal to the Quaternary North American ice complex, subject
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Diapirism of carbonate platforms subducted into the upper mantle Geology (IF 6.324) Pub Date : 2022-08-01 Mihai N. Ducea, Claire A. Currie, Constantin Balica, Iuliana Lazar, Ananya Mallik, Lucian Petrescu, Mihai Vlasceanu
Subduction of lithospheric plates at convergent margins leads to transport of materials once close to or at the surface of Earth to great depths. Some of them later return to the surface by magmatism or degassing, whereas others end up being stored in the mantle for long periods of time. The fate of carbon-bearing minerals in subduction is of particular interest because they can arbitrate the long-term
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Extensive evidence for a last interglacial Laurentide outburst (LILO) event Geology (IF 6.324) Pub Date : 2022-08-01 Yuxin Zhou, Jerry McManus
A catastrophic last interglacial Laurentide outburst (LILO) event approximately 125,000 years ago (125 ka) may have contributed to abrupt climate change during the last interglacial. It has been proposed that this event was an analog of the Holocene 8.2 ka event. We characterize in detail the (1) provenance, (2) timing, and (3) delivery mechanism of a layer of red sediments deposited across much of
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An explosive volcanic origin identified for dark sand in Aeolis Dorsa, Mars Geology (IF 6.324) Pub Date : 2022-08-01 Devon M. Burr, Christina E. Viviano, Timothy I. Michaels, Matthew Chojnacki, Robert E. Jacobsen
Dark, windblown (eolian) sand on Mars has produced significant geologic effects throughout Martian history. Although local and regional sand sources have been identified, a primary origin, or genesis, for Martian sand has not been demonstrated. This knowledge gap was recently heightened by the discovery of widespread sand motion, implying breakdown of grains to sub-sand sizes. To address the question
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Early incubation and prolonged maturation of large ignimbrite magma bodies: Evidence from the Southern Rocky Mountain volcanic field, Colorado, USA Geology (IF 6.324) Pub Date : 2022-08-01 Peter W. Lipman, Matthew J. Zimmerer, Amy K. Gilmer
Clusters of early central volcanoes in the mid-Cenozoic Southern Rocky Mountain volcanic field (SRMVF; southwestern Colorado, USA) record sites of initial magmatic focusing that led to assembly of sizable upper-crustal magma bodies capable of generating large ignimbrites. Peak growth at precursor andesitic volcanoes was followed by extended periods (0.5 to >2 m.y.) of reduced eruptive activity during
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A newly discovered subglacial lake in East Antarctica likely hosts a valuable sedimentary record of ice and climate change Geology (IF 6.324) Pub Date : 2022-08-01 Shuai Yan, Donald D. Blankenship, Jamin S. Greenbaum, Duncan A. Young, Lin Li, Anja Rutishauser, Jingxue Guo, Jason L. Roberts, Tas D. van Ommen, Martin J. Siegert, Bo Sun
The Princess Elizabeth Land sector of the East Antarctic Ice Sheet is a significant reservoir of grounded ice and is adjacent to regions that experienced great change during Quaternary glacial cycles and Pliocene warm episodes. The existence of an extensive subglacial water system in Princess Elizabeth Land (to date only inferred from satellite imagery) bears the potential to significantly impact the
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A tropically hot mid-Cretaceous North American Western Interior Seaway Geology (IF 6.324) Pub Date : 2022-08-01 Matthew M. Jones, Sierra V. Petersen, Allison N. Curley
The mid-Cretaceous thermal maximum (KTM) during Cenomanian to Santonian times from ca. 100 to 83 Ma is considered among Earth's warmest sustained intervals of the Phanerozoic. The time interval is also characterized by major paleoceanographic changes in the form of an oceanic anoxic event and the flooding of epicontinental seaways, such as the Western Interior Seaway in North America. We report carbonate
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U-Pb dating reveals multiple Paleoproterozoic orogenic events (Hamersley orogenic cycle) along the southern Pilbara margin (Australia) spanning the onset of atmospheric oxygenation Geology (IF 6.324) Pub Date : 2022-08-01 Birger Rasmussen, Jian-wei Zi, Janet Muhling
The early Paleoproterozoic was a time of unprecedented change in Earth's climate and surface environment. The key to resolving some of the controversies surrounding the timing and causes of these changes lies with supracrustal sequences, such as the 2.45–2.22 Ga Turee Creek Group in the southern Pilbara craton, northwestern Australia. The group preserves a predominantly siliciclastic sequence; however
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Permeability of subducted oceanic crust revealed by eclogite-facies vugs Geology (IF 6.324) Pub Date : 2022-08-01 Samuel Angiboust, Tom Raimondo
We report the finding of rare eclogite-facies vugs forming millimeter- to centimeter-sized pockets in meta-ophiolites from the western European Alps. Euhedral garnet crystals covering the vug walls display oscillatory chemical zoning for a wide range of major and trace elements, including Cr, Mn, and rare earth elements. Thermodynamic modeling revealed that closed-system fluid production through the
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Recurrent tectonic activity in northeastern Brazil during Pangea breakup: Constraints from U-Pb carbonate dating Geology (IF 6.324) Pub Date : 2022-08-01 Carlos E. Ganade, Caue R. Cioffi, João Pacífico Machado, Tiago Miranda, Leonardo B. Lopes, Roberto F. Weinberg, Maria Alcione Celestino, Bruno Carvalho, Marcel Guillong, Nick M.W. Roberts
Carbonate U-Pb dating of samples from rift-bounding faults of intracontinental basins in the Borborema province, northeastern Brazil, indicate recurrent tectonic activity during Pangea breakup lasting for >150 m.y. from the Late Triassic to the Paleocene, reactivating inherited strike-slip Neoproterozoic–Cambrian shear zones. Triassic ages indicate that brittle deformation started some 80 m.y. before
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Origin of Tibetan post-collisional high-K adakitic granites: Anatexis of intermediate to felsic arc rocks Geology (IF 6.324) Pub Date : 2022-07-01 Jian-Kang Yi, Di-Cheng Zhu, Roberto F. Weinberg, Qing Wang, Jin-Cheng Xie, Liang-Liang Zhang, Zhi-Dan Zhao
Potassium-rich adakitic rocks have been used to infer high-pressure (HP) melting of thickened or foundered mafic lower crust in post-collisional settings. However, their origin remains debated because of their potassic rather than sodic nature. We address this debate by investigating the source of post-collisional Oligocene high-K adakitic granites in southern Tibet, which are widely attributed to
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The problem of paleo-planforms Geology (IF 6.324) Pub Date : 2022-07-01 Sinéad J. Lyster, Alexander C. Whittaker, Elizabeth A. Hajek
Reconstructing river planform is crucial to understanding ancient fluvial systems on Earth and other planets. Paleo-planform is typically interpreted from qualitative facies interpretations of fluvial strata, but these can be inconsistent with quantitative approaches. We tested three well-known hydraulic planform predictors in Cretaceous fluvial strata (in Utah, USA) where there is a facies-derived
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Looking upstream with clumped and triple oxygen isotopes of estuarine oyster shells in the early Eocene of California, USA Geology (IF 6.324) Pub Date : 2022-07-01 Julia R. Kelson, Sierra V. Petersen, Nathan A. Niemi, Benjamin H. Passey, Allison N. Curley
The δ18O of carbonate minerals that formed at Earth's surface is widely used to investigate paleoclimates and paleo-elevations. However, a multitude of hydrologic processes can affect δ18O values, including mixing, evaporation, distillation of parent waters, and carbonate growth temperatures. We combined traditional carbon and oxygen isotope analyses with clumped (Δ47) and triple oxygen isotopes (Δ′17O)
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Apparent preservation of primary foraminiferal Mg/Ca ratios and Mg-banding in recrystallized foraminifera Geology (IF 6.324) Pub Date : 2022-07-01 Philip T. Staudigel, Eleanor H. John, Ben Buse, Paul N. Pearson, Caroline H. Lear
Trace element and δ18O values of foraminifera are widely used to reconstruct oceanic temperatures throughout the Cenozoic and beyond. Previous work evaluating the geochemistry of foraminifera with differing degrees of physical preservation have shown that Mg/Ca and δ18O paleothermometers give discrepant values in recrystallized tests, with planktonic oxygen isotopes often yielding significantly lower
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Metastable olivine within oceanic lithosphere in the uppermost lower mantle beneath the eastern United States Geology (IF 6.324) Pub Date : 2022-07-01 Fansheng Kong, Stephen S. Gao, Kelly H. Liu, Yinxia Fang, Hejun Zhu, Robert J. Stern, Jiabiao Li
Approximately two-thirds of Earth's outermost shell is composed of oceanic plates that form at spreading ridges and recycle back to Earth's interior in subduction zones. A series of physical and chemical changes occur in the subducting lithospheric slab as the temperature and pressure increase with depth. In particular, olivine, the most abundant mineral in the upper mantle, progressively transforms
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Late Holocene increase of winter precipitation in mid-continental North America from a seasonally resolved speleothem record Geology (IF 6.324) Pub Date : 2022-07-01 Cameron J. Batchelor, Shaun A. Marcott, Ian J. Orland, Kouki Kitajima
Subannual climate reconstructions of the Holocene are rare despite the ability of such records to provide a better understanding of the underlying factors that drive subannual climate variability. We used specialized confocal laser fluorescent microscope imaging and automated secondary ion mass spectrometry microanalysis to resolve a seasonal oxygen isotope (δ18O) record of a late Holocene–aged (2
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Infaunalization and resource partitioning during the Mesozoic marine revolution Geology (IF 6.324) Pub Date : 2022-07-01 Luis A. Buatois, M. Gabriela Mángano, Bhawanisingh Desai, Noelia B. Carmona, Fiona Burns, Dean Meek, Bruce Eglington
Infaunalization has been regarded as representing a response to increased predation pressures and is therefore central to the Mesozoic marine revolution, which gives pre-eminence to the role that enemy-directed evolution has played as a driving force of biotic change. Our ichnologic compilation from 39 Middle Triassic to Late Jurassic shallow-marine siliciclastic units allows us to evaluate the vertical
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Ancient roots of tungsten in western North America Geology (IF 6.324) Pub Date : 2022-07-01 V. Elongo, H. Falck, K.L. Rasmussen, L.J. Robbins, R.A. Creaser, Y. Luo, D.G. Pearson, C. Sarkar, E. Adlakha, M.C. Palmer, J.M. Scott, K. Hickey, K. Konhauser, P. Lecumberri-Sanchez
The highly irregular and localized distribution of tungsten deposits worldwide constitutes a supply challenge for basic industries such as steel and carbides. Over Earth's history, tungsten has preferentially accumulated at paleocontinental margins formed during the breakup of supercontinents. Later crustal thickening of these paleogeographic regions and the magmas they produce are associated with
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Laser-ablation Lu-Hf dating reveals Laurentian garnet in subducted rocks from southern Australia Geology (IF 6.324) Pub Date : 2022-07-01 Dillon A. Brown, Alexander Simpson, Martin Hand, Laura J. Morrissey, Sarah Gilbert, Renée Tamblyn, Stijn Glorie
Garnet is a fundamental expression of metamorphism and one of the most important minerals used to constrain the thermal conditions of the crust. We used innovative in situ laser-ablation ICP-MS/MS Lu-Hf geochronology to demonstrate that garnet in metapelitic rocks enclosing Cambrian eclogite in southern Australia formed during Laurentian Mesoproterozoic metamorphism. Garnet porphyroblasts in amphibolite-facies
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Oceanic isostasy as a trigger for the rift-to-drift transition Geology (IF 6.324) Pub Date : 2022-07-01 James A. Conder
A long-standing missing link in our understanding of the Wilson cycle is how a continental rift transitions to seafloor spreading. The variety of rift structures and transition timings at rift margins do not easily lend themselves to some specific degree of strain and/or magmatism as the tipping point. Invariably ignored in the process, but a potential key to the conundrum, is the isostatic response
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Fluid inclusion evidence for extreme overpressure induced by gas generation in sedimentary basins Geology (IF 6.324) Pub Date : 2022-07-01 Xiaolin Wang, Wenxuan Hu, Ye Qiu, Yifeng Liu, Dong Jia, Jian Cao, Xian Liu, Yiquan Li
Formation and preservation of extremely high-pressure fluid in sedimentary basins is critical to understanding petroleum accumulation and basin evolution; however, this issue remains poorly understood due to a lack of key evidence. We present fluid inclusion evidence from the Paleozoic black shales in the eastern Sichuan Basin (South China block) that suggest that gas generation can form methane-saturated
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Oxygen isotope evidence for progressively assimilating trans-crustal magma plumbing systems in Iceland Geology (IF 6.324) Pub Date : 2022-07-01 A. Caracciolo, S.A. Halldórsson, E. Bali, E.W. Marshall, H. Jeon, M.J. Whitehouse, J.D. Barnes, G.H. Guðfinnsson, M. Kahl, M.E. Hartley
The oxygen isotope composition of mantle-derived melts can place important constraints on how magmas are processed as they traverse the crust. Assimilation of crustal material is a crucial aspect of basalt petrogenesis, as it affects the chemical and rheological characteristics of eruptive magmas at active volcanoes. We report oxygen isotope (δ18O) and trace element (TE) data from a suite of well-characterized
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Relationship between glacial CO2 drawdown and mercury cycling in the western South Atlantic: An isotopic insight Geology (IF 6.324) Pub Date : 2022-07-01 Thiago S. Figueiredo, Bridget A. Bergquist, Thiago P. Santos, Ana Luiza S. Albuquerque, Emmanoel Vieira Silva-Filho
Pronounced changes in the deep Atlantic circulation occurred during glacial stages, which affected the global carbon distribution and the biogeochemical cycles of other elements. Previous studies demonstrated that oceanic mercury is sensitive to the same kind of processes that affect the carbon cycle in glacial–interglacial time scales. We used Hg isotopes to elucidate Hg cycling during the last two
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Atypical landslide induces speedup, advance, and long-term slowdown of a tidewater glacier Geology (IF 6.324) Pub Date : 2022-07-01 Maximillian Van Wyk de Vries, Andrew D. Wickert, Kelly R. MacGregor, Camilo Rada, Michael J. Willis
Atmospheric and oceanic warming over the past century have driven rapid glacier thinning and retreat, destabilizing hillslopes and increasing the frequency of landslides. The impact of these landslides on glacier dynamics and resultant secondary landslide hazards are not fully understood. We investigated how a 262 ± 77 × 106 m3 landslide affected the flow of Amalia Glacier, Chilean Patagonia. Despite
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Seismic anisotropy in the central Tien Shan unveils rheology-controlled deformation during intracontinental orogenesis Geology (IF 6.324) Pub Date : 2022-07-01 Bingfeng Zhang, Xuewei Bao, Yixian Xu
The initiation and evolution of compressional intracontinental orogens are favored by rheologically weak lithosphere underneath; however, how this weakened lithosphere responds to the regional stress regime remains vigorously debated. The Tien Shan mountains in central Asia provide the best example to illustrate the deep deformational responses to intracontinental orogenesis. We present new constraints
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Cenozoic sediment bypass versus Laramide exhumation and erosion of the Eagle Ford Group: Perspective from modelling of organic and inorganic proxy data (Maverick Basin, Texas, USA) Geology (IF 6.324) Pub Date : 2022-07-01 Alexandra S. Robinson, Annabel Dale, Thierry Adatte, Cédric M. John
The Cenozoic unconformity above the Late Cretaceous carbonates within the Maverick Basin is a unique feature of Texas (USA). Hypotheses accounting for the unconformity include (1) Cenozoic sediment bypass, and (2) ~6400 m of erosion during the Laramide orogeny. Both hypotheses have different implications for the burial history of the Eagle Ford Group (EFG) and for our understanding of the Laramide
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Plate tectonic–like cycles since the Hadean: Initiated or inherited? Geology (IF 6.324) Pub Date : 2022-07-01 Ross N. Mitchell, Christopher J. Spencer, Uwe Kirscher, Simon A. Wilde
Interpretation of Earth's oldest preserved crustal archive, the Jack Hills zircon of Western Australia, has been controversial in terms of the onset of plate tectonics. We conduct time-series analysis on hafnium isotopes of the Jack Hills zircon and reveal an array of statistically significant cycles that are reminiscent of plate-tectonic subduction. At face value, such cycles may suggest early Earth
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Pothole-like depressions in the chamber floor of the Sudbury Igneous Complex, Canada Geology (IF 6.324) Pub Date : 2022-07-01 S.Yu. Chistyakova, R.M. Latypov
The magmatic stratigraphy of the Sudbury Igneous Complex (Canada) is thought to have resulted from closed-system differentiation of an initially homogeneous impact melt sheet. The topography of its upward-growing chamber floor is therefore thought to have been planar and subhorizontal. However, we report on the discovery of a large pothole-like depression (~300 m in depth and ~550 m in width) in the
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Plagioclase archives of depleted melts in the oceanic crust Geology (IF 6.324) Pub Date : 2022-07-01 David A. Neave, Olivier Namur
Mid-ocean ridge and ocean-island basalts provide vital but incomplete insights into mantle chemistry. For example, high-anorthite plagioclase is generally too refractory and incompatible-element depleted to have crystallized from the melts that carry it to the surface. Moreover, erupted basalts rarely preserve the extreme isotopic and incompatible-element depletions found in some primitive melt inclusions
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Sulfide-associated hydrothermal dolomite and calcite reveal a shallow burial depth for Alpine-type Zn-(Pb) deposits Geology (IF 6.324) Pub Date : 2022-07-01 M. Giorno, L. Barale, C. Bertok, M. Frenzel, N. Looser, M. Guillong, S.M. Bernasconi, L. Martire
Difficulties in dating Mississippi Valley–type (MVT) mineral deposits and the often closely associated dolomitization have led to controversy regarding their origin. We report the first radiometric ages for the Gorno mining district in northern Italy, an example of the Alpine subclass of MVT deposits. U-Pb ages of hydrothermal carbonates pre- and postdating the ore-forming event show that base-metal
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Cenozoic mountain building in eastern China and its correlation with reorganization of the Asian climate regime Geology (IF 6.324) Pub Date : 2022-07-01 Jingxing Yu, Dewen Zheng, Jianzhang Pang, Chaopeng Li, Ying Wang, Yizhou Wang, Yuqi Hao, Peizhen Zhang
The Cenozoic Asian climate system experienced a transformation from a zonal pattern to a monsoon-dominant pattern around the Paleogene-Neogene boundary. A series of dynamic mechanisms, such as uplift of the Tibetan Plateau, retreat of the Paratethys Sea, expansion of the South China Sea, and decreasing atmospheric CO2 content, has been suggested to be responsible for the transformation of the Asian
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Significance of U-Pb detrital zircon geochronology for mudstone provenance Geology (IF 6.324) Pub Date : 2022-06-01 Paul J. Sylvester, A. Kate Souders, Rui Liu
Detrital zircon U-Pb studies of mudstone provenance are rare but may preferentially fingerprint distal zircon sources. To examine this issue, Pierre Shale and Trinidad Sandstone deposited in a Late Cretaceous deltaic environment in the Raton Basin, Colorado (USA), were measured for detrital zircon U-Pb age by laser ablation–inductively coupled plasma–mass spectrometry. Two major detrital zircon age
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Nanoscale isotopic evidence resolves origins of giant Carlin-type ore deposits Geology (IF 6.324) Pub Date : 2022-06-01 E.A. Holley, A. Fulton, C. Jilly-Rehak, C. Johnson, M. Pribil
The western North American Great Basin's Carlin-type deposits represent the largest accumulation of gold in the Northern Hemisphere. The controversy over their origins echoes the debate between Neptunists and Plutonists at the birth of modern geology: were the causative processes meteoric or magmatic? Sulfur isotopes have long been considered key to decoding metal cycling in the Earth's crust, but
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Can deepwater bottom currents generate clinothems? An example of a large, asymmetric mounded drift in Upper Jurassic to Lower Cretaceous sediments from northwestern Australia Geology (IF 6.324) Pub Date : 2022-06-01 O. Mantilla, F.J. Hernández-Molina, N. Scarselli
Clinoforms and clinothems are ubiquitous in shallow marine and shelf margin environments, where they show remarkable seaward progradation trends. Consensus holds that these features do not form in deepwater settings. This study describes an example of a large, asymmetric mounded deposit formed in Upper Jurassic to Lower Cretaceous sediments along the Exmouth Plateau (offshore northwestern Australia)
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Greenland tidewater glacier advanced rapidly during era of Norse settlement Geology (IF 6.324) Pub Date : 2022-06-01 Danni M. Pearce, James M. Lea, Douglas W.F. Mair, Brice R. Rea, J. Edward Schofield, Nicholas A. Kamenos, Kathryn M. Schoenrock, Lukasz Stachnik, Bonnie Lewis, Iestyn Barr, Ruth Mottram
Our ability to improve prognostic modeling of the Greenland Ice Sheet relies on understanding the long-term relationships between climate and mass flux (via iceberg calving) from marine-terminating tidewater glaciers (TWGs). Observations of recent TWG behavior are widely available, but long-term records of TWG advance are currently lacking. We present glacial geomorphological, sedimentological, archaeological
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Five million years of high atmospheric CO2 in the aftermath of the Permian-Triassic mass extinction Geology (IF 6.324) Pub Date : 2022-06-01 Michael M. Joachimski, Johann Müller, Timothy M. Gallagher, Gregor Mathes, Daoliang L. Chu, Fedor Mouraviev, Vladimir Silantiev, Yadong D. Sun, Jinnan N. Tong
The end-Permian mass extinction, the largest biological crisis in Earth history, is currently understood in the context of Siberian Traps volcanism introducing large quantities of greenhouse gases to the atmosphere, culminating in the Early Triassic hothouse. In our study, the late Permian and Early Triassic atmospheric CO2 history was reconstructed by applying the paleosol pCO2 barometer. Atmospheric
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Episodic fluid flow in an eclogite-facies shear zone: Insights from Li isotope zoning in garnet Geology (IF 6.324) Pub Date : 2022-06-01 William F. Hoover, Sarah Penniston-Dorland, Lukas Baumgartner, Anne-Sophie Bouvier, Besim Dragovic, Michele Locatelli, Samuel Angiboust, Philippe Agard
Episodic fluid overpressure and escape is invoked as a cause or consequence of many subduction-zone seismic phenomena but can be challenging to constrain in exhumed high-pressure metamorphic rocks. In situ measurements of lithium isotopes in garnet reveal evidence of episodic fluid transport in a subduction shear zone now exposed in the Monviso ophiolite (Western Alps). Garnet from an eclogite block
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Calcite U-Pb ages constrain petroleum migration pathways in tectonic complex basins Geology (IF 6.324) Pub Date : 2022-06-01 Fuyun Cong, Jinqiang Tian, Fang Hao, Andrew R.C. Kylander-Clark, Wenqing Pan, Baoshou Zhang
Tracing secondary oil migration pathways is critical for understanding petroleum system evolution histories. Traditional tools (e.g., molecular indicators and numerical modeling) utilized for evaluating oil migration processes either lead to ambiguous interpretations or only provide qualitative estimates. We quantitatively constrain secondary oil migration processes under an absolute time frame by
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Magmatism at oceanic core complexes on the ultraslow Southwest Indian Ridge: Insights from near-seafloor magnetics Geology (IF 6.324) Pub Date : 2022-06-01 Fei Zhou, Jérôme Dyment, Chunhui Tao, Tao Wu
Oceanic core complexes (OCCs) and detachment faults play a key role in crustal accretion at slow and ultraslow spreading centers. We investigated the effect of different magma supply at three OCCs of the Southwest Indian Ridge using high-resolution deep-sea bathymetric and magnetic data. The average equivalent thickness of extrusive basalt deduced from the magnetic anomalies, a proxy for magma supply
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Cumulate granites: A perspective from new apatite MgO partition coefficients Geology (IF 6.324) Pub Date : 2022-06-01 Qiong-Yao Zhan, Di-Cheng Zhu, Roberto F. Weinberg, Qing Wang, Jin-Cheng Xie, Liang-Liang Zhang, Zhi-Dan Zhao
Apatite is a powerful research tool because it is common in various rocks and incorporates many chemical elements. Understanding how elements partition between apatite and melt and the controls on the partition are critical for applications of apatite. It has been recently proposed that MgO content in magmatic apatite is proportional to that of the melt, highlighting the potential importance of this
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Deformation and metasomatism recorded by single-grain apatite petrochronology Geology (IF 6.324) Pub Date : 2022-06-01 Margaret L. Odlum, Drew A. Levy, Daniel F. Stockli, Lisa D. Stockli, Joel W. DesOrmeau
The timing and processes of ductile deformation and metasomatism can be documented using apatite petrochronology. We integrated microstructural, U-Pb, and geochemical analyses of apatite grains from an exhumed mylonitic shear zone in the St. Barthélémy Massif, Pyrenees, France, to understand how deformation and metasomatism are recorded by U-Pb dates and geochemical patterns. Electron backscatter diffraction
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Deep-sea hiatuses track the vigor of Cenozoic ocean bottom currents Geology (IF 6.324) Pub Date : 2022-06-01 Adriana Dutkiewicz, R. Dietmar Müller
The deep-sea stratigraphic record is full of gaps. These hiatuses track changes in ocean circulation and chemistry, but determining their timing and causes has been limited by sparse data and incomplete knowledge of ocean gateway evolution in earlier studies. We combine a significantly expanded, age-calibrated deep-sea stratigraphic database with a global tectonic and paleo–water depth model to investigate
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How old are the Jack Hills metasediments really?: The case for contamination of bedrock by zircon grains in transported regolith Geology (IF 6.324) Pub Date : 2022-06-01 P.D. Kinny, C. Clark, C.L. Kirkland, M. Hartnady, J. Gillespie, T.E. Johnson, B. McDonald
The enigmatic occurrence of Neoarchean- and Proterozoic-aged zircon grains in some samples of metasedimentary rocks from the Jack Hills, Western Australia, that otherwise appear to have been deposited before 3.0 Ga is explained by contamination with embedded zircon grains sourced from transported regolith. Zircon U-Pb age spectra obtained by laser ablation–inductively coupled plasma mass spectrometry
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Re-Os geochronology for the Cambrian SPICE event: Insights into euxinia and enhanced continental weathering from radiogenic isotopes Geology (IF 6.324) Pub Date : 2022-06-01 Alan D. Rooney, Alexie E.G. Millikin, Per Ahlberg
The late Cambrian Steptoean positive carbon isotope excursion (SPICE) represents a major perturbation to the global carbon cycle and was associated with trilobite extinctions and expansion of anoxic and/or euxinic water masses during episodes of eustatic sea-level change. We present a new Re-Os age together with Os and Nd isotope stratigraphy and major- and trace-element data from the Alum Shale Formation
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Groundwater age persistence in topography-driven groundwater flow over paleohydrogeologic time scales Geology (IF 6.324) Pub Date : 2022-06-01 Yueqing Xie, Andrew J. Love, Craig T. Simmons, Adrian Costar, Jichun Wu
The Pleistocene-Holocene climate transition resulted in a dramatic reduction in groundwater recharge in many aquifers in arid and semiarid regions throughout the world. This study conducted numerical experiments to compare the evolution of groundwater hydraulics and age patterns in arid and semiarid aquifers in response to transient conditions associated with recharge decline from the Pleistocene to
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Stagnation and tearing of the subducting northwest Pacific slab Geology (IF 6.324) Pub Date : 2022-06-01 Muchen Sun, Youqiang Yu, Stephen S. Gao, Kelly H. Liu
Despite numerous observational and geodynamic modeling studies, the presence of the northwest Pacific slab tear and its influence on mantle dynamics remain controversial. By imaging the mantle transition zone (MTZ) discontinuities beneath the Japan Sea and adjacent areas, we demonstrate an ESE-WNW elongated zone with significant MTZ thinning extending from central Honshu, Japan, to the Korean Peninsula
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A Tonian volcano-sedimentary succession in Newfoundland, eastern North America: A post-Grenvillian link to the Asgard Sea? Geology (IF 6.324) Pub Date : 2022-06-01 Susan Strowbridge, Aphrodite Indares, Greg Dunning, Markus Wälle
Early Tonian bimodal volcanic and sedimentary rocks (the Pine Pond succession) were identified in the Appalachians of eastern Laurentia for the first time, with U-Pb ages of igneous zircon at 951.4 ± 9 Ma for a felsic tuff and 952 ± 10 Ma for a crosscutting granite sheet. This Neoproterozoic succession is part of the East Pond metamorphic suite on the Baie Verte Peninsula (Newfoundland, Canada), which
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Nanoscale trace-element zoning in pyrite framboids and implications for paleoproxy applications Geology (IF 6.324) Pub Date : 2022-06-01 Daniel D. Gregory, Libor Kovarik, Sandra D. Taylor, Daniel E. Perea, Jeremy D. Owens, Nicole Atienza, Timothy W. Lyons
Pyrite framboids (spherical masses of nanoscale pyrite) are among the earliest textures of pyrite to form in sediments. It has been proposed that their trace-element (TE) contents can be used to track the TE composition of the water column in which they formed. However, it is not clear how these TEs are associated with the framboidal pyrite grains. For instance, it is important to know whether they
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Reconstructing source-to-sink systems from detrital zircon core and rim ages Geology (IF 6.324) Pub Date : 2022-06-01 Li Liu, Daniel F. Stockli, Timothy F. Lawton, Jie Xu, Lisa D. Stockli, Majie Fan, Gregory C. Nadon
Grenville-age (1.3–0.9 Ga) zircons represent one of the most ubiquitous detrital zircon (DZ) age modes on Earth. In North America, given the widespread occurrence of Grenville basement, Grenville DZs are commonly viewed as nondiagnostic with regard to source region in provenance studies. Systematic recovery of DZ core-rim U-Pb ages makes it possible to identify and differentiate previously indistinguishable