Geology Pub Date : 2024-02-01 DOI: 10.1130/g51766.1

Lingtong Meng, Y. Chu, Wei Lin, Ross N. Mitchell, Liang Zhao

{"title":"Bulldoze and rebuild: Modifying cratonic lithosphere via removal and replacement induced by continental subduction","authors":"Lingtong Meng, Y. Chu, Wei Lin, Ross N. Mitchell, Liang Zhao","doi":"10.1130/g51766.1","DOIUrl":"https://doi.org/10.1130/g51766.1","url":null,"abstract":"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 of the Yangtze block (YB) during the early Mesozoic, we report the presence of the YB crust embedded in the overriding craton. Combining our new results with previous observations, we argue that during 250–220 Ma, a 200-km-long tract of the NCC lithosphere was bulldozed by the subducted YB, resulting in a lithospheric suture far from the suture zone at the surface. This lithospheric removal occurred at middle-lower crustal levels (16–20 km depth)—much shallower than previously thought possible. The bulldozed NCC lithosphere was replenished by the subducted YB continental lithosphere rather than the asthenosphere, thus terminating the lithosphere modification. With essentially no net loss of lithosphere during deep continental subduction, the NCC maintained its stability until Early Cretaceous paleo-Pacific oceanic subduction. This “bulldoze and rebuild” model can thus account for how a craton maintains stability during a collision with another continental plate.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139825535","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

Bulldoze and rebuild: Modifying cratonic lithosphere via removal and replacement induced by continental subduction 推土与重建：通过大陆俯冲引起的移除和置换改变板块岩石圈

Geology Pub Date : 2024-02-01 DOI: 10.1130/g51766.1

Lingtong Meng, Y. Chu, Wei Lin, Ross N. Mitchell, Liang Zhao

{"title":"Bulldoze and rebuild: Modifying cratonic lithosphere via removal and replacement induced by continental subduction","authors":"Lingtong Meng, Y. Chu, Wei Lin, Ross N. Mitchell, Liang Zhao","doi":"10.1130/g51766.1","DOIUrl":"https://doi.org/10.1130/g51766.1","url":null,"abstract":"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 of the Yangtze block (YB) during the early Mesozoic, we report the presence of the YB crust embedded in the overriding craton. Combining our new results with previous observations, we argue that during 250–220 Ma, a 200-km-long tract of the NCC lithosphere was bulldozed by the subducted YB, resulting in a lithospheric suture far from the suture zone at the surface. This lithospheric removal occurred at middle-lower crustal levels (16–20 km depth)—much shallower than previously thought possible. The bulldozed NCC lithosphere was replenished by the subducted YB continental lithosphere rather than the asthenosphere, thus terminating the lithosphere modification. With essentially no net loss of lithosphere during deep continental subduction, the NCC maintained its stability until Early Cretaceous paleo-Pacific oceanic subduction. This “bulldoze and rebuild” model can thus account for how a craton maintains stability during a collision with another continental plate.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139885673","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

Resolving pressure differences within the Grand Canyon Precambrian basement: Implications for Proterozoic tectonics 解析大峡谷前寒武纪基底内的压力差异：对新生代构造的影响

Geology Pub Date : 2024-01-25 DOI: 10.1130/g51706.1

Suzanne Autrey-Mulligan, Chloe Bonamici, Michael L. Williams, K.E. Karlstrom, C. Condit

{"title":"Resolving pressure differences within the Grand Canyon Precambrian basement: Implications for Proterozoic tectonics","authors":"Suzanne Autrey-Mulligan, Chloe Bonamici, Michael L. Williams, K.E. Karlstrom, C. Condit","doi":"10.1130/g51706.1","DOIUrl":"https://doi.org/10.1130/g51706.1","url":null,"abstract":"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 (QuiG) barometry and pseudosection modeling to determine pressures in domains (“blocks”) with evidence of higher and lower peak metamorphic grades. New pressure-temperature (P-T) paths constructed using this integrated approach show that a hot block sample reached 7 kbar and a cold block sample never surpassed 5 kbar, revealing an ∼2 kbar P difference between hot and cold blocks and delineating distinct P-T paths for these domains in the UGG. Our findings suggest that hot and cold blocks were likely metamorphosed at different crustal levels within a pre-Yavapai, Paleoproterozoic orogen and were subsequently juxtaposed during and/or after the Yavapai Orogeny at mid-crustal levels. The deformation that produced differential vertical displacement of crustal blocks post-dated peak metamorphism and could reflect extensional collapse of a large orogen and/or renewed folding and thrusting at the Paleoproterozoic Laurentian plate margin.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139598085","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

Life in the Cambrian shallows: Exceptionally preserved arthropod and mollusk microfossils from the early Cambrian of Sweden 寒武纪浅滩中的生命瑞典早寒武纪保存完好的节肢动物和软体动物微化石

Geology Pub Date : 2024-01-25 DOI: 10.1130/g51829.1

Ben J. Slater

{"title":"Life in the Cambrian shallows: Exceptionally preserved arthropod and mollusk microfossils from the early Cambrian of Sweden","authors":"Ben J. Slater","doi":"10.1130/g51829.1","DOIUrl":"https://doi.org/10.1130/g51829.1","url":null,"abstract":"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 Cambrian biotas. An alternate means of detecting soft-bodied Cambrian fauna, independent of paleobathymetry, is to use acid maceration to extract microscopic organic remains of non-mineralized animals, known as “small carbonaceous fossils” (SCFs). Here, a hitherto unknown diversity of Cambrian arthropod and mollusk remains are reported from shallow-marine sediments (Cambrian Stage 3 Mickwitzia Sandstone, Sweden). These microfossils comprise a variety of arthropod cuticles preserving sub-micron-scale anatomy alongside abundant radular mouthparts from mollusks—among the oldest known arthropod and molluscan SCFs on record. Significantly, at least three distinct types of fossil radula are identifiable (uniseriate, distichous, and polystichous forms), revealing that substantial diversification of the basic molluscan radula had already taken place by the early Cambrian. These cryptic elements of the biota—otherwise undetectable in such deposits—offer novel insights into Cambrian primary consumers as well as aspects of the fauna that are absent from deeper-water BST deposits.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139596768","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

Rapid development of spiral garnets during subduction zone metamorphism revealed from high-resolution Sm-Nd garnet geochronology 高分辨率 Sm-Nd 石榴石地质年代学揭示俯冲带变质过程中螺旋榴石的快速发展

Geology Pub Date : 2024-01-25 DOI: 10.1130/g51882.1

Thomas P. Farrell, Domingo Aerden, E. Baxter, Paul G. Starr, Michael L. Williams

{"title":"Rapid development of spiral garnets during subduction zone metamorphism revealed from high-resolution Sm-Nd garnet geochronology","authors":"Thomas P. Farrell, Domingo Aerden, E. Baxter, Paul G. Starr, Michael L. Williams","doi":"10.1130/g51882.1","DOIUrl":"https://doi.org/10.1130/g51882.1","url":null,"abstract":"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 for the garnet core (13.64 ± 0.31 Ma), mantle (13.41 ± 0.37 Ma), and rim (13.34 ± 0.45 Ma) indicate rapid garnet growth and are consistent with published garnet ages interpreted to reflect high-pressure metamorphism in the region. Thermodynamic analysis indicates garnets grew during subduction at ∼1.5−2.0 GPa and 570−600 °C. The core to rim duration of spiral garnet growth was just a few hundred thousand years. While other zoned garnet studies have shown similar rapid growth in subduction zone settings, this is the first documentation of such rapid growth of a spiral garnet. Combining this garnet growth duration with the magnitude of spiral inclusion trail curvature, we compute a strain rate of ∼10−13 s−1, an order of magnitude faster than all previous spiral garnet studies. We interpret that these spiral garnets recorded a rapid pulse of deformation and strain during the final stages of subduction and incipient exhumation.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139598442","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

A late refugium for Classopollis in the Paleocene Lower Wilcox Group along the Texas Gulf Coast 德克萨斯州海湾沿岸古新世下威尔科克斯群中的晚期Classopollis栖息地

Geology Pub Date : 2024-01-22 DOI: 10.1130/g51772.1

Vann Smith, Angela Hessler, Lorena Moscardelli, David Bord, Iulia Olariu, Maria Antonieta Lorente, Evan Sivil, Xiuju Liu

{"title":"A late refugium for Classopollis in the Paleocene Lower Wilcox Group along the Texas Gulf Coast","authors":"Vann Smith, Angela Hessler, Lorena Moscardelli, David Bord, Iulia Olariu, Maria Antonieta Lorente, Evan Sivil, Xiuju Liu","doi":"10.1130/g51772.1","DOIUrl":"https://doi.org/10.1130/g51772.1","url":null,"abstract":"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 family in the Paleocene have previously been reported in China, Argentina, and potentially the Rocky Mountains of the United States. The highest relative abundances of Classopollis pollen were found in delta front, lagoon, and shoreface depositional paleoenvironments marked by high mud-fraction Sr/Ba (a geochemical proxy for salinity), and abundances generally increased down section in older Paleocene strata. The high relative abundance of Classopollis pollen in the well samples, the rarity of reworked Mesozoic palynomorphs, the generally good preservation of Classopollis pollen, and the similarity of Classopollis fluorescence spectra to other in situ Paleocene pollen all provide strong evidence for the survival of the Cheirolepidiaceae family in the coastal salt marshes of Texas through at least the late Paleocene.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139608811","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

Rare earth element transport and mineralization linked to fluids from carbonatite systems 与碳酸盐岩系统流体有关的稀土元素迁移和成矿作用

Geology Pub Date : 2024-01-19 DOI: 10.1130/g51531.1

Emanuel Mororó, M. Berkesi, Z. Zajacz, T. Guzmics

引用次数: 0

Increase in magma supply to Sakurajima volcano’s (Japan) shallow magma chamber over the past 500 years 过去 500 年樱岛火山（日本）浅层岩浆室岩浆供应量的增加

Geology Pub Date : 2024-01-18 DOI: 10.1130/g51763.1

Christian Huber, Atsushi Toramaru

引用次数: 0

From dome to duplex: Convergent gravitational collapse explains coeval intracratonic doming and nappe tectonics, central Australia 从穹隆到复式：汇聚引力塌陷解释了澳大利亚中部同时期的地壳内穹隆和岩层构造

Geology Pub Date : 2024-01-16 DOI: 10.1130/g51721.1

Youseph Ibrahim, Patrice F. Rey, D. Whitney, C. Teyssier, Françoise Roger, Valérie Bosse, Bénédicte Cenki

引用次数: 0

In situ U-Pb dating of Jurassic dinosaur bones from Sichuan Basin, South China 华南四川盆地侏罗纪恐龙骨骼的原位 U-Pb 定年

Geology Pub Date : 2024-01-16 DOI: 10.1130/g51872.1

Liang Qi, Mingcai Hou, Jacob A. Mulder, Peter A. Cawood, Yao Guo, Shitou Wu, Liangxuan Jiao, Xiaolin Zhang, Ouyang Hui

{"title":"In situ U-Pb dating of Jurassic dinosaur bones from Sichuan Basin, South China","authors":"Liang Qi, Mingcai Hou, Jacob A. Mulder, Peter A. Cawood, Yao Guo, Shitou Wu, Liangxuan Jiao, Xiaolin Zhang, Ouyang Hui","doi":"10.1130/g51872.1","DOIUrl":"https://doi.org/10.1130/g51872.1","url":null,"abstract":"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 bone cavities of a Jurassic sauropod from the Sichuan Basin, South China. Early diagenetic calcite yielded a U-Pb age of 165.3 ± 3.6/5.6 Ma, in agreement with a maximum depositional age of 165.8 ± 1.0 Ma from detrital zircon ages of the surrounding rocks, suggesting that diagenesis occurred shortly after the death of the sauropod. This new age demonstrates that the best-known Jurassic large sauropod faunas in South China are much older than those in North America and Africa, suggesting the geographical isolation of South China. Authigenic apatite U-Pb dating on the fibrolamellar bones from the same sauropod gave a distinctly younger age, indicating more complex U-Pb system behavior, possibly due to U uptake by residual organic matter and recrystallization of apatite after early diagenesis. Our findings demonstrate that U-Pb dating of calcite cements within bone cavities has significant potential for constraining the burial age of vertebrate fossils, which could aid in constructing a more robust temporal framework for the radiation and evolution of vertebrates.","PeriodicalId":503125,"journal":{"name":"Geology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139619434","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

Geology最新文献