Journal of Geology最新文献_第9页

Geodynamics of Late Paleozoic to Early Mesozoic Magmatism in South China: Insights from the Genesis of the Late Permian S-Type Granites in the Yunkai Massif 华南晚古生代至早中生代岩浆活动的地球动力学——从云开地块晚二叠世S型花岗岩成因看

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-04-06 DOI: 10.1086/708465

Long Qing, Yao-Hui Jiang, Fo-Guang Du

{"title":"Geodynamics of Late Paleozoic to Early Mesozoic Magmatism in South China: Insights from the Genesis of the Late Permian S-Type Granites in the Yunkai Massif","authors":"Long Qing, Yao-Hui Jiang, Fo-Guang Du","doi":"10.1086/708465","DOIUrl":"https://doi.org/10.1086/708465","url":null,"abstract":"Late Paleozoic granites have rarely been reported in South China. We present the first detailed zircon laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb dating and in situ Hf isotopic and whole-rock element geochemical and Sr-Nd isotopic data for two late Permian granitic plutons (Napeng and Shicun) recently identified in the Yunkai massif, South China. In addition, we assess their origin and relationship to the geodynamics of late Paleozoic to early Mesozoic magmatism in South China. The Napeng pluton consists of cordierite- and/or garnet-bearing biotite granites, and the Shicun pluton is composed of two-mica granites and muscovite granites. Detailed LA-ICP-MS zircon U-Pb dating shows that both plutons were emplaced in the late Permian and contain abundant inherited zircons with a spread of ages, including Neoarchean-Paleoproterozoic, Neoproterozoic-Cambrian, Ordovician-Silurian, Devonian, Carboniferous, and early Permian. The cordierite- and/or garnet-bearing biotite granites are strongly peraluminous and have higher maficity than experimental melts of metasedimentary rocks. Both the two-mica and muscovite granites are also strongly peraluminous but have similar maficity to experimental melts of metasedimentary rocks. All the granites have high initial 87Sr/86Sr, negative εNd(t), and εHf(t) (in situ zircon). Detailed petrographic and geochemical characteristics of the studied granites suggest that they are S-type granites and were formed by partial melting of subducted oceanic sediments of the eastern Paleo-Tethys Ocean within the depth of mantle region to normal lower crust in the continental collision zone. Our new data suggest that the origin of the Napeng and Shicun granites might mark the onset of the continental collision between the Indochina and South China Blocks with the initial closure of the eastern Paleo-Tethys Ocean at the beginning of the late Permian.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"128 1","pages":"275 - 301"},"PeriodicalIF":1.8,"publicationDate":"2020-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/708465","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43138258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

First Evidence of Late Paleoproterozoic/Early Mesoproterozoic Sediment Deposition and Magmatism in the Central Aravalli Orogen (NW India) 印度西北部Aravalli造山带中部晚古元古代/早中元古代沉积与岩浆作用的首个证据

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-02-13 DOI: 10.1086/707235

P. Kaur, A. Zeh, N. Chaudhri, Jaideep K. Tiwana

{"title":"First Evidence of Late Paleoproterozoic/Early Mesoproterozoic Sediment Deposition and Magmatism in the Central Aravalli Orogen (NW India)","authors":"P. Kaur, A. Zeh, N. Chaudhri, Jaideep K. Tiwana","doi":"10.1086/707235","DOIUrl":"https://doi.org/10.1086/707235","url":null,"abstract":"The nature and stratigraphic position of the Beawar gneiss unit (BGU) within the central Aravalli orogen (NW India) remain unresolved. These rocks are currently assigned to the South Delhi Supergroup, assumed to be deposited at 1200–1000 Ma. This interpretation is challenged by new results of petrography, combined with U-Pb dating, Hf isotope analyses of zircon, and whole-rock geochemistry. These data reveal that the BGU consists of both ortho- and paragneisses and that the protoliths were formed and/or deposited at the boundary between the late Paleoproterozoic and early Mesoproterozoic at ca. 1600 Ma. U-Pb ages of detrital zircon grains from a paragneiss sample indicate a maximum deposition age of 1614±14 Ma and major age peaks at 2528, 1916, 1840, 1725, and 1617 Ma. These ages, in combination with Hf isotope data, suggest that the source area consisted mainly of felsic magmatic rocks similar to those exposed within the Aravalli orogen and in the Bundelkhand Craton and/or in terranes within the Central Indian Tectonic Zone. A single detrital zircon with an Eoarchean crystallization age of ca. 3630 Ma and Hf model age of 4.05 Ga point to the existence of the Hadean crust. Magmatic zircon in an orthogneiss sample yields an upper-intercept age of 1581±24 Ma, indicating granite emplacement during the early Mesoproterozoic. Combined geochemical and Hf isotope data suggest that the orthogneiss protolith was a strongly peraluminous S-type granite, formed by melting of surrounding country rocks perhaps within a convergent setting. U-Pb ages (980–960 Ma) of zircon overgrowths and monazite grains suggest that all the rocks were affected by a Grenvillian metamorphic overprint during the assembly of Rodinia.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"128 1","pages":"109 - 129"},"PeriodicalIF":1.8,"publicationDate":"2020-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/707235","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46274751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 16

Genesis and Petrology of Postcollisional Rare-Metal-Bearing Granites in the Arabian Shield: A Case Study of Aja Ring Complex, Northern Saudi Arabia 阿拉伯地盾碰撞后含稀有金属花岗岩的成因与岩石学——以沙特阿拉伯北部阿贾环形杂岩为例

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-02-13 DOI: 10.1086/707236

Bassam A. Abuamarah

{"title":"Genesis and Petrology of Postcollisional Rare-Metal-Bearing Granites in the Arabian Shield: A Case Study of Aja Ring Complex, Northern Saudi Arabia","authors":"Bassam A. Abuamarah","doi":"10.1086/707236","DOIUrl":"https://doi.org/10.1086/707236","url":null,"abstract":"The Jabal Aja Ring Complex (ARC) is a late Ediacaran composite pluton of postcollisional A-type granites in the northeastern part of the Arabian Shield. It is an elliptical body with discontinuous ring-shaped outcrops due to later faulting. Field relationships enable the recognition of two main phases of magmatic activity in the ARC. The early phase represents the core of the intrusion (monzogranite, syenogranite, granophyre, and alkali feldspar granite) surrounded by the last phase (alkali volcanics and alkaline/peralkaline granites). The contacts between two phases are gradational and/or sharp, indicating their emplacement within a very short time period before the complete crystallization of the earlier phase. The ARC is alkaline to peralkaline rare-metal granites with the common geochemical characteristics of postcollisional intraplate A-type rocks. The pronounced negative Eu anomalies (Eu/Eu*=0.14−0.25) reflect extreme magmatic fractionation and perhaps the effects of late fluid-rock interaction. All A-type rocks of the ARC retain a positive Nb-Ta anomaly that increases from the early phase to the most evolved alkaline/peralkaline granites. They define geochemical signatures reflecting their derivation from the same magma sources that evolved through fractional crystallization with crustal contamination. The geochemical characteristics of the A-type granites of ARC reflect remelting of previously formed arc material. The mafic microgranular enclaves represent metamorphic rocks derived from or in the deeper part of the crust and represent the source rocks from which the granitic magma was generated by partial melting. The early phase of magmatism of the ARC represents melts derived from partial melting of lower or middle crustal sources during the postcollisional stage that fractionated to give the various granitic rocks. The absence of mafic xenoliths in the late stage of the ARC indicates that the contribution of crustal sources to magma generation is absent in the late stage.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"128 1","pages":"131 - 156"},"PeriodicalIF":1.8,"publicationDate":"2020-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/707236","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47285887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

Coupled Microfracturing and Chemical Weathering of Precambrian Quartzite in the Extremely Humid and Tectonically Active Shillong Plateau, NE India: Implications for In Situ Quartz Weathering and Quartz Silt Production 印度东北部极度潮湿和构造活跃的西龙高原前寒武纪石英岩的微压裂和化学风化耦合作用:对原位石英风化和石英粉生成的启示

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-02-13 DOI: 10.1086/707326

S. Sensarma, R. V. S. Shimyaphy, T. Chakraborty

{"title":"Coupled Microfracturing and Chemical Weathering of Precambrian Quartzite in the Extremely Humid and Tectonically Active Shillong Plateau, NE India: Implications for In Situ Quartz Weathering and Quartz Silt Production","authors":"S. Sensarma, R. V. S. Shimyaphy, T. Chakraborty","doi":"10.1086/707326","DOIUrl":"https://doi.org/10.1086/707326","url":null,"abstract":"The origin of quartz silt, the most abundant detrital particle, is controversial. Quartz silt is generally considered to be broken quartz sand, attributed to glacial, eolian, and/or long fluvial transport. In this article, we highlight the origin of in situ quartz silt in deep weathering profiles (≤7 m) over Precambrian quartzite (>92% quartz with or without 6%–8% mica, feldspar-free), a rock known to be resistant to weathering, in the Shillong Plateau (NE India). This region is one of the most tectonically active and the rainiest place on Earth. We discuss, for the first time, detailed field petrographic and microstructural evidence including diverse microfracturing and dissolution morphologies in quartz, from bedrock through saprolite (2–3 m) and nodular zone (NZ; ∼0.5 m) to soil (≤2–5 m), for quartz silt production through coupled mechanical-chemical processes over 3–4 My in the plateau. Progressive size reduction of quartz from medium sand (1.13–1.36 Φ) in bedrock quartzite through fine sand in saprolite (2.55–2.67 Φ) and the NZ (2.12–4.4 Φ) to coarse and medium silt in soil (4–5 Φ), with concomitant increase in clay mineral (≤80%), characterizes the profiles. Quartzite microfracturing, linked to exhumation and/or seismicity, provided pathways for acidic water to attack and promote chemical weathering in quartz, which in turn effected microfracture widening, porosity enhancement, and weakening of quartz in a positive feedback loop. Mica-microbe interactions facilitated fluid acidity, causing Al and Fe mobilization and more clay mineral production, and enhanced corrosive potential for in situ quartz dissolution in feldspar-free quartzite. Coupled brittle disintegration and chemical weathering of even extremely resistant quartz-rich rocks thus contribute toward long-term regolith development and global quartz silt production.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"128 1","pages":"201 - 226"},"PeriodicalIF":1.8,"publicationDate":"2020-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/707326","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43915725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

A Prediction Model of Vitrinite Reflectance for Suppression of Organic-Matter Maturation by Overpressure 超压抑制有机物成熟的镜质反射率预测模型

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-02-06 DOI: 10.1086/707237

Maoguo Hou, M. Zha, Xiujian Ding, Ablimit Imin, R. Lai, Shouxu Pan, Yutao Ding

{"title":"A Prediction Model of Vitrinite Reflectance for Suppression of Organic-Matter Maturation by Overpressure","authors":"Maoguo Hou, M. Zha, Xiujian Ding, Ablimit Imin, R. Lai, Shouxu Pan, Yutao Ding","doi":"10.1086/707237","DOIUrl":"https://doi.org/10.1086/707237","url":null,"abstract":"Vitrinite reflectance is the most commonly used index in the study of source rock evaluation, diagenetic stage division, basin simulation, and diagenesis. Because data on vitrinite reflectance are limited, many prediction models have been proposed to address this problem. However, these models may fail to predict vitrinite reflectance effectively in overpressured basins because overpressure can suppress organic-matter maturation. Overpressure appears to reduce the degree of disorder in the hydrocarbon generation reaction system and to increase the mechanical work against the force of pore fluid that occurs as the volume of the activated complex increases, thereby reducing the preexponential factor and increasing the activation energy of the hydrocarbon generation reaction; therefore, organic-matter maturation is slowed. In this article, the reasons for the abnormally low vitrinite reflectance in the overpressured system were analyzed, which revealed that overpressure is interpreted as significantly suppressing organic-matter maturation. A new prediction model for vitrinite reflectance, A-Ea-Ro, is proposed that accounts for the suppression of overpressure in organic-matter maturation based on data from wells in the Fukang Sag in the Junggar Basin, northwestern China. The overpressure is modeled by introducing a preexponential factor and activation energy in this model. Based on measured drilling and geochemical data and simulated data, the overpressure controlling factors were optimized by a nonlinear constrained programming method and assigned 151.23 MPa and 30.65 kJ·mol−1·MPa−1, respectively. Prediction models including A-Ea-Ro were applied to wells Fu10 and Mu7 of Fukang Sag. The reflectance values predicted by the model A-Ea-Ro, applied to wells Fu10 and Mu7, were in good agreement with the measured values. This model provides a closer match between predicted and observed vitrinite reflectance values for this study area.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"128 1","pages":"189 - 200"},"PeriodicalIF":1.8,"publicationDate":"2020-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/707237","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43009114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Origin and Formation Process of Gabbro and Diorite Xenoliths in the Northern Part of Uromieh-Dokhtar Magmatic Belt, NW Iran: Constraints from Mineral and Whole-Rock Chemistries 伊朗Uromieh-Dokhtar岩浆带北部辉长岩和闪长岩捕虏体的成因和形成过程:矿物化学和全岩化学的约束

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-02-06 DOI: 10.1086/707325

A. Khezerlou, M. Grégoire, N. Amel, M. Moayyed, A. Jahangiri, Mohammad Kilzi

{"title":"Origin and Formation Process of Gabbro and Diorite Xenoliths in the Northern Part of Uromieh-Dokhtar Magmatic Belt, NW Iran: Constraints from Mineral and Whole-Rock Chemistries","authors":"A. Khezerlou, M. Grégoire, N. Amel, M. Moayyed, A. Jahangiri, Mohammad Kilzi","doi":"10.1086/707325","DOIUrl":"https://doi.org/10.1086/707325","url":null,"abstract":"Gabbro and diorite xenoliths occur within the alkaline trachyandesites in the northern part of Uromieh-Dokhtar magmatic belt (NW Iran). The host volcanic rocks are located on the upper Miocene sediments; therefore, they are probably Plio-Quaternary in age. The texture of xenoliths is granular, and the gabbro xenoliths are classified into two groups based on their petrographic characteristics and mineral chemistry. Based on chemical analyses, xenoliths show a subalkaline to slightly alkaline magmatic trend. Thermobarometric results indicate that gabbro and diorite xenoliths formed within the middle crustal level. All xenolith samples are light rare earth elements (LREEs) enriched and depleted in Ta, Zr, and Nb. These features can be explained by the subduction of the Neotethys. The LREE enrichment as well as negative Th, Ti, Nb, and Zr anomalies and positive Pb anomaly are in agreement with an origin through partial melting of an enriched mantle previously affected by metasomatism processes linked to mantle wedge-derived melts (fluids). Different REE concentration levels and patterns for Group 1 gabbro, Group 2 gabbro, and diorite xenoliths point out that their parental melts were not the same. Those forming the Group 1 gabbro xenoliths originated from melting of garnet mantle lherzolite, whereas the parental melts from Group 2 gabbro and diorite xenoliths originated from melting of spinel-garnet mantle lherzolite. The 86Sr/87Sr and 143Nd/144Nd ratios and chemical composition of minerals are different for host volcanic rocks and xenoliths; therefore, we may conclude that the parental melts of the different groups of xenoliths and host volcanic rocks differ in composition.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"128 1","pages":"227 - 246"},"PeriodicalIF":1.8,"publicationDate":"2020-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/707325","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42677721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Nature of the Eastern Boundary of the Mesozoic Ordos Basin and the Formation of the Lüliangshan Anticline 鄂尔多斯盆地中生代东界性质与吕梁山背斜的形成

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-02-05 DOI: 10.1086/707346

Heng Zhao, Jin Zhang, J. Qu, Beihang Zhang, Long Yun, Jinyi Li, Pengfei Niu, F. Nie

{"title":"Nature of the Eastern Boundary of the Mesozoic Ordos Basin and the Formation of the Lüliangshan Anticline","authors":"Heng Zhao, Jin Zhang, J. Qu, Beihang Zhang, Long Yun, Jinyi Li, Pengfei Niu, F. Nie","doi":"10.1086/707346","DOIUrl":"https://doi.org/10.1086/707346","url":null,"abstract":"The Mesozoic to Cenozoic intraplate deformation of the North China Craton (NCC) is an intriguing phenomenon that led to different evolutions of the Ordos Basin and the eastern part of the NCC. Located in the central part of the NCC, the Lüliangshan is regarded as a boundary between the Ordos Basin and the eastern NCC, but the exact location of this boundary is still debated. Our field investigations suggest that the Lüliangshan anticline is a classical Mesozoic basement-involved anticline. The Lishi fault on the west of the southern part of the Lüliangshan anticline is argued to be a large fault and the east boundary of the Ordos Basin. However, our investigations show that it is not a continuous single fault but a deformation zone composed of several segments without connection along the strike. In front of the western Lüliangshan, this tectonic zone is a top-to-the-west breakthrough thrust placing the western Lüliangshan basement-involved anticline in the hanging wall with limited displacement. Field investigations show that the traditional view of the northern segment of the Lishi fault as a boundary between blocks is not clear. With a similar deformation style, the southern Lishi fault passes Lishi City, extends northeastward, connects to the Ximafang fault, and then extends to link with the Kouquan fault as the west boundary of the Datong Basin. All these faults show a map pattern of relay array. The eastern margin of the Ordos Basin was deformed by a series of thrusts that controlled the basement-involved folds. The Lüliangshan anticline and its boundary faults were formed in the Late Jurassic, and the driving force of the intraplate deformation is inferred to the westward low-angle subduction of the Paleo-Pacific plate from the east.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"128 1","pages":"157 - 187"},"PeriodicalIF":1.8,"publicationDate":"2020-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/707346","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41432714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Index to Volume 113 第113卷索引

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-01-01 DOI: 10.1353/clw.2020.0045

引用次数: 0

Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ∼12,800 Years Ago: A Reply 非凡的生物质燃烧事件和影响冬季由新仙女木宇宙撞击触发~ 12,800年前:一个答复

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-01-01 DOI: 10.1086/706265

W. Wolbach, Joanne P. Ballard, P. Mayewski, A. Kurbatov, T. Bunch, M. LeCompte, V. Adedeji, I. Israde-Alcántara, R. Firestone, W. Mahaney, A. Melott, C. R. Moore, W. Napier, G. A. Howard, K. Tankersley, B. Thomas, J. Wittke, John R. Johnson, S. Mitra, J. Kennett, G. Kletetschka, A. West

引用次数: 7

Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ∼12,800 Years Ago, Parts 1 and 2: A Discussion 大约12,800年前新仙女木宇宙撞击引发的非同寻常的生物质燃烧事件和撞击冬季，第1部分和第2部分:讨论

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-01-01 DOI: 10.1086/706264

V. Holliday, P. Bartlein, A. Scott, J. Marlon

{"title":"Extraordinary Biomass-Burning Episode and Impact Winter Triggered by the Younger Dryas Cosmic Impact ∼12,800 Years Ago, Parts 1 and 2: A Discussion","authors":"V. Holliday, P. Bartlein, A. Scott, J. Marlon","doi":"10.1086/706264","DOIUrl":"https://doi.org/10.1086/706264","url":null,"abstract":"Wolbach et al. published two papers on the Younger Dryas Impact Hypothesis (YDIH)—the paleoenvironmental effects of a purported cosmic impact at the beginning of the Younger Dryas Chronozone (YDC). Part 1 includes a selective summary of previous discussions of the YDIH but leaves out key reviews, uncritically accepts previous interpretations of purported impact, and fails to take into account abundant criticisms and contradictory data. A discussion of icecore evidence focuses only on the beginning of the YDCrather thanona longer interval thatwouldallow the context of claimed impact indicators to be evaluated. The exceptionalism claimed for many of the key data points is the result of exaggerations, and the graphical analyses themselves are not reproducible. Part 2 presents data from sedimentary records. The authors assume that impacts triggered widespread fires, but the evidence for such a link between extraterrestrial impacts and wildfires is weak. The presence of charcoal at the beginning of the YDC (YDB) fails to unambiguously support the hypothesis of impact-related fires because there is also a large peak at the end of the YDC. Stratigraphic markers used to argue for widespread burning, such as the Usselo soil of northwest Europe and the blackmat of the southwesternUnited States,were shownby their original investigators to have no plausible link to an impact event. Human population decline in North America is not supported by abundant published","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"128 1","pages":"69 - 94"},"PeriodicalIF":1.8,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/706264","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47938459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 20