Geology最新文献_第4页

Vestiges of Earth’s earliest depleted mantle reservoir 地球最早的枯竭地幔储层遗迹

Geology Pub Date : 2024-03-13 DOI: 10.1130/g51936.1

Jordan K. Wright, Asish R. Basu

{"title":"Vestiges of Earth’s earliest depleted mantle reservoir","authors":"Jordan K. Wright, Asish R. Basu","doi":"10.1130/g51936.1","DOIUrl":"https://doi.org/10.1130/g51936.1","url":null,"abstract":"There is a paucity of evidence preserved in the rock record regarding Earth’s earliest enriched crust and its complementary depleted mantle during the Hadean. In recent years, vestiges of these early reservoirs have been inferred by examination of Hf isotope systematics compiled from zircons. The Singhbhum craton of Eastern India, for example, preserves only the existence of an enriched (εHf <0) crustal reservoir during the Hadean−Eoarchean, with the notable absence of a depleted mantle reservoir signature (εHf >0) until ca. 3.5 Ga. Here we report a new Sm-Nd isochron for the Lower Lava greenstones of the western Iron Ore Group from the Singhbhum craton, confirming a 3.42 ± 0.14 Ga crystallization age with an initial εNd of +5.7 ± 2.5. This is the highest positive εNd value derived from an isochron of this age. We infer that this depleted mantle source is a vestige complementary to the primary crust following planetary differentiation. Furthermore, we present U-Pb zircon ages for a 3.39 ± 0.02 Ga tuff that lies stratigraphically above the Lower Lava and <30 cm below an extensive conformable banded iron formation (BIF). This age implies that the western Iron Ore Group’s BIF is the largest economic-grade iron formation of its Paleoarchean age, suggesting that free atmospheric oxygen existed as more than just whiffs at this time.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140247304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Competing effects of crustal shortening, thermal inheritance, and surface processes explain subsidence anomalies in inverted rift basins 地壳缩短、热继承和地表过程的竞争效应解释了倒置裂谷盆地的沉降异常现象

Geology Pub Date : 2024-03-12 DOI: 10.1130/g51971.1

Éva Oravecz, A. Bálazs, Taras Gerya, Dave A. May, László Fodor

{"title":"Competing effects of crustal shortening, thermal inheritance, and surface processes explain subsidence anomalies in inverted rift basins","authors":"Éva Oravecz, A. Bálazs, Taras Gerya, Dave A. May, László Fodor","doi":"10.1130/g51971.1","DOIUrl":"https://doi.org/10.1130/g51971.1","url":null,"abstract":"Structural inversion of rifted basins is generally associated with surface uplift and denudation of the sedimentary infill, reflecting the active contractional deformation in the crust. However, worldwide examples of inverted rifts show contrasting basin-scale subsidence and widespread sedimentation patterns during basin inversion. By conducting a series of three-dimensional coupled geodynamic and surface processes models, we investigated the dynamic controls on these subsidence anomalies during the successive stages of rifting and basin inversion, and we propose a new evolutionary model for this process. Our models show that the inherited thermo-rheological properties of the lithosphere influence the initial strain localization and subsequent migration of crustal deformation during inversion. The sense of the vertical movements (i.e., uplift or subsidence), however, is not directly linked to the underlying crustal stress patterns; rather, it reflects the balance among contraction-induced tectonic uplift, postrift thermal subsidence of the inherited lithosphere, and sediment redistribution. Based on the interplay among the competing differential vertical movements with different amplitudes and wavelengths, inversion of rifted basins may lead to the growth of intraplate orogens, or the contraction-driven localized uplift may be hindered by the thermal sag effects of the inherited shallow lithosphere-asthenosphere boundary, resulting in basin-scale subsidence. In such basins, dating the first erosional surfaces and other unconformities may not provide accurate timing for the onset of inversion.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140249075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Comprehensive seismic evidence for the inducing mechanism of extremely shallow 2019 Changning Ms 6.0 earthquake by solution salt mining, Sichuan Basin, China 中国四川盆地溶盐开采诱发 2019 年长宁 Ms 6.0 极浅层地震机制的综合地震学证据

Geology Pub Date : 2024-03-11 DOI: 10.1130/g51699.1

U. Anyiam, Jiawei Qian, Yuyang Tan, Haijiang Zhang

引用次数: 0

An ongoing lithospheric dripping process beneath northeast China and its impact on intraplate volcanism 中国东北地下正在进行的岩石圈滴落过程及其对板块内火山活动的影响

Geology Pub Date : 2024-03-06 DOI: 10.1130/g51861.1

Feiyu Lin, Liang Qi, Nan Zhang, Zhen Guo

{"title":"An ongoing lithospheric dripping process beneath northeast China and its impact on intraplate volcanism","authors":"Feiyu Lin, Liang Qi, Nan Zhang, Zhen Guo","doi":"10.1130/g51861.1","DOIUrl":"https://doi.org/10.1130/g51861.1","url":null,"abstract":"Unique intraplate volcano eruptions and westward volcano migration since the Oligocene have been observed in northeast China, where an overriding continental zone is tectonically controlled by the subduction of the northwestern Pacific plate and the opening of Japan Sea. Interestingly, these intraplate magmatic events occur around a subsiding basin (the Songliao Basin), but no volcanic activity has been observed within the Songliao Basin. The geodynamic mechanism responsible for these volcanoes remains unclear. To address the geodynamic process beneath northeast China, we conducted numerical models constrained by data from regional reconstruction and seismic and volcanic studies. The vertical velocity field of mantle convection and lithospheric partial melting structures derived from our models show that mantle upwelling and melting centers migrate from east to west in northeast China with the westward propagation of the sub-horizontal slab in the transition zone, leading to the observed volcano migration. Also, with the subduction retreat of the northwestern region of the Pacific plate and the opening of the Japan Sea, significant lithospheric thickness differences developed between the Changbaishan-Mudanjiang region and the Songliao Basin, leading to lithospheric unstable dripping. This dripping structure prevents the partial melting of the lithosphere but facilitates the subsidence of the Songliao Basin. Moreover, the lithospheric dripping model successfully predicts upper mantle structures consistent with the proposed tomography model, the observed Moho depth, and surface topography variations. Thus, lithospheric dripping induced by lithospheric thickness differences and the retreating subduction of the Pacific slab provides a robust mechanism for the unique geodynamic processes in northeast China.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140078293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Spatiotemporal distribution of giant magnetofossils holds clues to their biological origin 巨型磁化石的时空分布提供了生物起源的线索

Geology Pub Date : 2024-03-04 DOI: 10.1130/g51809.1

Pengfei Xue, Liao Chang

{"title":"Spatiotemporal distribution of giant magnetofossils holds clues to their biological origin","authors":"Pengfei Xue, Liao Chang","doi":"10.1130/g51809.1","DOIUrl":"https://doi.org/10.1130/g51809.1","url":null,"abstract":"Micrometer-size magnetite crystals with peculiar morphologies, such as spearhead, spindle, needle, and giant bullet, known as giant magnetofossils, were previously identified in marine sediments mainly during the Eocene epoch. The origin of these unusual magnetite crystals remains unclear because no known modern analogues have been found, and data about their spatiotemporal distribution are sparse. Here, using electron microscope observations, we performed a large-scale spatiotemporal search for these mysterious magnetite crystals. We report the occurrence of giant magnetofossils in variable marine sedimentary environments, including the first report in modern South Atlantic and Indian Ocean environments and the oldest occurrence at ca. 93 Ma in the North Atlantic Ocean. Grain-size data for the giant magnetofossils in the Southwest Pacific and North Atlantic Oceans suggest that the dimension of spearheads is sensitive to regional environments during similar warming periods but is insensitive to environmental conditions across the distinct geological periods at the same locality. The grain-size distributions of needles and giant bullets do not show significant changes in diverse environments. These observations greatly expand the known temporal and geographic distribution of giant magnetofossils, shedding new light on their likely biological origin.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140079641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Impact of rift history on the structural style of intracontinental rift-inversion orogens 断裂历史对大陆内断裂-反转造山带结构风格的影响

Geology Pub Date : 2024-03-01 DOI: 10.1130/g51489.1

Dylan A. Vasey, J. Naliboff, Eric Cowgill, Sascha Brune, A. Glerum, Frank Zwaan

{"title":"Impact of rift history on the structural style of intracontinental rift-inversion orogens","authors":"Dylan A. Vasey, J. Naliboff, Eric Cowgill, Sascha Brune, A. Glerum, Frank Zwaan","doi":"10.1130/g51489.1","DOIUrl":"https://doi.org/10.1130/g51489.1","url":null,"abstract":"Although many collisional orogens form after subduction of oceanic lithosphere between two continents, some orogens result from strain localization within a continent via inversion of structures inherited from continental rifting. Intracontinental rift-inversion orogens exhibit a range of structural styles, but the underlying causes of such variability have not been extensively explored. We use numerical models of intracontinental rift inversion to investigate the impact of parameters including rift structure, rift duration, post-rift cooling, and convergence velocity on orogen structure. Our models reproduce the natural variability of rift-inversion orogens and can be categorized using three endmember styles: asymmetric underthrusting (AU), distributed thickening (DT), and localized polarity flip (PF). Inversion of narrow rifts tends to produce orogens with more localized deformation (styles AU and PF) than those resulting from wide rifts. However, multiple combinations of the parameters we investigated can produce the same structural style. Thus, our models indicate no unique relationship between orogenic structure and the conditions prior to and during inversion. Because the style of rift-inversion orogenesis is highly contingent upon the rift history prior to inversion, knowing the geologic history that preceded rift inversion is essential for translating orogenic structure into the processes that produced that structure.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140084544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Strong seismic anisotropy due to upwelling flow at the root of the Yellowstone mantle plume 黄石地幔羽流根部的上涌流动导致强烈的地震各向异性

Geology Pub Date : 2024-03-01 DOI: 10.1130/g51919.1

Jonathan Wolf, Mingming Li, Anne A. Haws, Maureen D. Long

引用次数: 0

Magnetite-apatite ores record widespread involvement of molten salts 磁铁矿-磷灰石矿石记录了熔盐的广泛参与

Geology Pub Date : 2024-03-01 DOI: 10.1130/g51887.1

Xinyue Xu, W. Bain, F. Tornos, J. Hanchar, Hector M. Lamadrid, Bernd Lehmann, Xiaochun Xu, Jeffrey A. Steadman, Ralph S. Bottrill, Majid Soleymani, A. Rajabi, Peng Li, Xuehai Tan, Shihong Xu, A. Locock, M. Steele‐MacInnis

引用次数: 0

Lithospheric mantle as a metal storage reservoir for orogenic gold deposits in active continental margins: Evidence from Hg isotopes 岩石圈地幔作为活动大陆边缘造山运动金矿床的金属储存库：来自汞同位素的证据

Geology Pub Date : 2024-03-01 DOI: 10.1130/g51871.1

Jing-Yuan Zhang, Kun-Feng Qiu, Runsheng Yin, Zheng-Yu Long, Yue-Chuan Feng, Hao-Cheng Yu, Zi-Yue Gao, Jun Deng

{"title":"Lithospheric mantle as a metal storage reservoir for orogenic gold deposits in active continental margins: Evidence from Hg isotopes","authors":"Jing-Yuan Zhang, Kun-Feng Qiu, Runsheng Yin, Zheng-Yu Long, Yue-Chuan Feng, Hao-Cheng Yu, Zi-Yue Gao, Jun Deng","doi":"10.1130/g51871.1","DOIUrl":"https://doi.org/10.1130/g51871.1","url":null,"abstract":"The subcontinental lithospheric mantle (SCLM) is now suggested by many workers to play a role in the formation of orogenic gold deposits in active continental margins, given that the gold and volatiles may be introduced into the SCLM during plate subduction. The giant Cretaceous Jiaodong gold province within the North China block occurs in a convergent margin setting where there is no terrane accretion, thus eliminating from consideration the commonly accepted metal and fluid source reservoir for orogenic gold—the metamorphosed upper crust of an active orogenic belt. Thus, the auriferous fluids were released below the high-grade Archean cratonic rocks from either enriched SCLM or directly from the subducted oceanic slab. Mercury (Hg) isotopes allow fingerprinting of isotopically distinct reservoirs, discriminating between the two possibilities. We present Hg isotope data for a set of pyrite grains, native gold, and lamprophyres from six main gold districts in the Jiaodong gold province. These samples dominantly yielded near-zero Δ199Hg (0‰ ± 0.1‰), within uncertainty of the mantle Δ199Hg value. The results provide novel evidence that the SCLM predominantly controlled the Hg budget of the Jiaodong gold deposits, implying that the SCLM acted as a buffer for the crustal mass-independent fractionation Hg signatures and a storage reservoir for gold and volatiles. Consequently, during slab subduction, gold and volatiles were recycled and stored within the SCLM and were later released from the mantle during uplift and relaxation of compressional tectonics.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140092534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Detrital isotopic record of a retreating accretionary orogen: An example from the Patagonian Andes 退缩增生造山运动的碎屑同位素记录：以巴塔哥尼亚安第斯山脉为例

Geology Pub Date : 2024-02-28 DOI: 10.1130/g51918.1

F.M. Rey, M. Malkowski, J. Fosdick, S.C. Dobbs, M. Calderón, M. Ghiglione, S.A. Graham

{"title":"Detrital isotopic record of a retreating accretionary orogen: An example from the Patagonian Andes","authors":"F.M. Rey, M. Malkowski, J. Fosdick, S.C. Dobbs, M. Calderón, M. Ghiglione, S.A. Graham","doi":"10.1130/g51918.1","DOIUrl":"https://doi.org/10.1130/g51918.1","url":null,"abstract":"U-Pb zircon geochronology and isotopic records have played an influential role in our understanding of convergent margin dynamics. Orogenic cyclicity models link tectonic regimes with magmatic isotopic signatures in advancing orogens, relating compressional regimes with evolved signatures and extension with juvenile signatures; however, such frameworks may not apply for retreating orogens, which commonly produce substantial crustal heterogeneities during backarc rifting and ocean spreading. We explore the Mesozoic to Cenozoic Patagonian Andes tectonic evolution, combining U-Pb zircon ages, bulk rock εNd, and new detrital zircon εHf from the retroarc basin to understand the associated magmatic arc evolution during retreat and advance of the margin. Our results reveal a protracted phase of isotopically juvenile magmatism between 150 and 80 Ma, which began during backarc extension and persisted long after the margin switched to a contractional regime. We propose that the prolonged juvenile isotopic trend started mainly due to trenchward migration of the arc during backarc extension (150−120 Ma) and persisted due to partial melting of underthrusted juvenile attenuated and oceanic crust during backarc basin closure (120−80 Ma). This interpretation implies that tectonic stress alone does not predict isotopic trends, and factors like assimilation or the composition of underthrusted crust are important controls on magmatic isotopic composition, especially in retreating and transitional orogens.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140419568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0