Journal of Geology最新文献_第6页

Early Paleozoic Arc Magmatism and Accretionary Orogenesis in the Indochina Block, Southeast Asia

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2021-01-01 DOI: 10.1086/713727

N. Trọng, K. Zong, Yongsheng Liu, Yu Yuan, P. T. Hieu, L. Dung, P. Minh

{"title":"Early Paleozoic Arc Magmatism and Accretionary Orogenesis in the Indochina Block, Southeast Asia","authors":"N. Trọng, K. Zong, Yongsheng Liu, Yu Yuan, P. T. Hieu, L. Dung, P. Minh","doi":"10.1086/713727","DOIUrl":"https://doi.org/10.1086/713727","url":null,"abstract":"Southeast Asia plays a key role in the evolution of the eastern Tethys, which is characterized by accretion and amalgamation of numerous terranes since early Paleozoic. In the present study, an early Paleozoic granitoid sequence from the Kontum massif in the central Indochina block was investigated to reveal the early Paleozoic accretionary orogenesis of the eastern Tethys. Early Paleozoic Kontum granitoids include diorites and granites. Early Ordovician (485–473 Ma) Ben Giang diorites show high Mg#, Cr and Ni contents, and negative Nb-Ta and positive Pb anomalies as well as positive zircon ɛHf(t) values (+6.2 to +10), probably reflecting the melting of a metasomatized mantle wedge. Late Ordovician (457–453 Ma) Dien Binh hornblende-bearing diorites and granites exhibit low Mg#, Cr and Ni contents, and negative Nb-Ta and positive Pb anomalies as well as negative zircon ɛHf(t) values (−8.7 to −4.2), which is interpreted to reflect the reworking of ancient continental mafic crust during subduction. In contrast, the Silurian (422 Ma) Dai Loc muscovite-bearing granites are characterized by relatively high A/CNK and heavy rare earth element contents, and a negative Eu anomaly, corresponding to a typical S-type granite affinity. Their negative zircon ɛHf(t) values (−6.0 to +0.6) suggest that a petrogenesis linked to reworking of crustal sediments. In combination with the widespread occurrence of coeval high-pressure metamorphism, we suggest that an advancing accretionary orogenesis was responsible for the generation of the early Paleozoic magmatic arc in the Kontum massif. Such magmatic arc systems dominated the early Paleozoic evolution of the northern Gondwana margin during the subduction of the Proto-Tethys.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"129 1","pages":"33 - 48"},"PeriodicalIF":1.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/713727","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42245499","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

A New 40Ar/39Ar Analysis Method of Volcanoclastic Strata to Determine Eruption Periods—Example of Xintaimen, China 火山碎屑地层40Ar/39Ar分析确定喷发时期的新方法——以新台门为例

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2021-01-01 DOI: 10.1086/713685

Xin Zhou, J. Ji, Jing Zhou, Lhamo Yungchen, Wuxun Quan, J. Tu

{"title":"A New 40Ar/39Ar Analysis Method of Volcanoclastic Strata to Determine Eruption Periods—Example of Xintaimen, China","authors":"Xin Zhou, J. Ji, Jing Zhou, Lhamo Yungchen, Wuxun Quan, J. Tu","doi":"10.1086/713685","DOIUrl":"https://doi.org/10.1086/713685","url":null,"abstract":"The Jehol Biota is famous for its diversity of Early Cretaceous fossils preserved under large amounts of pyroclastic materials. However, the precise determination on the ages of volcanoclastic strata is challenging, because of their complex provenance. The solution to this problem may lie in the greatly improved geochronological methods, such as the 40Ar/39Ar geochronology. In this study, we use the laser fusion 40Ar/39Ar dating method to date volcanoclastic samples and apply statistical analyses of the acquired apparent ages to determine the volcanic eruption periods. From the 12 volcanoclastic samples analyzed in this study, we obtained 262 apparent ages that vary from 85.5 to 153.6 Ma. By fitting these apparent ages with a Gaussian mixture distribution model, we find three age clusters that are normally distributed, with each cluster statistically representing an eruption period. The mean values of the three normal distributions are 90.37±2.72 (1σ), 109.89±4.94, and 125.26±10.01 Ma. A comparison of our results with a statistical analysis of literature data indicates that volcanic activities occurred over a wide spatial scale across western Liaoning Province during the two older periods, whereas during the last time period, eruptions occurred more locally and belonged to the final stage of volcanic eruptions in the basin. The method and results reported in this study provide a good example of (1) dating volcanoclastic materials using the 40Ar/39Ar method to determine the time periods of volcanic activities and (2) investigating the stratigraphic correlation in complex volcanoclastic basins.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"129 1","pages":"63 - 76"},"PeriodicalIF":1.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/713685","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46412520","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: 0

Source of Detritus in Subducted Turbidites, Tectonic Mélange, Port Macquarie Block, Southern New England Orogen, Australia—A Geochemical Perspective 澳大利亚新英格兰造山带南部麦夸里港地块俯冲浊积岩碎屑物来源——地球化学视角

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2021-01-01 DOI: 10.1086/713684

R. Offler, R. Boyd

{"title":"Source of Detritus in Subducted Turbidites, Tectonic Mélange, Port Macquarie Block, Southern New England Orogen, Australia—A Geochemical Perspective","authors":"R. Offler, R. Boyd","doi":"10.1086/713684","DOIUrl":"https://doi.org/10.1086/713684","url":null,"abstract":"A tectonic mélange containing blueschists and eclogites, Middle Ordovician mid-ocean ridge basalt, cherts, and clastic sediments occurs at Port Macquarie in the southern New England Orogen, Australia. The clastics are quartz-poor and are dominated by mafic volcanic and fragmented plagioclase clasts; felsic volcanic clasts are less common. They exhibit erosional bases, graded bedding, load structures, and lithologies ranging from laminated mudstones to pebbly sandstones. Based on these features, they are interpreted as turbidites. During subduction, these turbidites were deformed and metamorphosed under prehnite–pumpellyite and lower greenschist facies conditions. Geochemically, they have a calc-alkaline, intra-oceanic arc signature; show no recycling; and have been derived from a provenance dominated by mafic volcanic rocks of basaltic-andesite composition. Further, chemical index of alteration (44–69) and Index of Compositional Variability (0.8–2.4) data reveal they show little weathering and are immature. The lack of weathering of rocks in a location where tropical climatic conditions existed is attributed to extreme erosion associated with a dynamic setting resulting in rapid transportation of the sediments to the fore arc basin and subsequently to the trench. As a consequence, little time was available for weathering to take place. The detritus in the turbidites is thought to have been derived from Late Ordovician volcanics in the Macquarie Arc and fore arc basin sequences of the Murrawong Formation. The cherts with which they are associated record both a continental and oceanic arc geochemical signature.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"129 1","pages":"49 - 62"},"PeriodicalIF":1.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/713684","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47398629","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: 0

Revised Provenance, Depositional Environment, and Maximum Depositional Age for the Baraboo ( Baraboo的修订物源、沉积环境和最大沉积年龄(

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2021-01-01 DOI: 10.1086/713687

E. Stewart, L. Brengman, E. Stewart

{"title":"Revised Provenance, Depositional Environment, and Maximum Depositional Age for the Baraboo (","authors":"E. Stewart, L. Brengman, E. Stewart","doi":"10.1086/713687","DOIUrl":"https://doi.org/10.1086/713687","url":null,"abstract":"Up to 2 km of siliciclastic and chemical sedimentary rocks, metamorphosed to greenschist facies, are preserved in the Baraboo Hills of southern Wisconsin. The strata compose two sedimentary successions separated by an angular unconformity. The lower succession includes the Baraboo quartzite, Seeley slate, and Freedom Formation, and the upper includes the Dake quartzite and Rowley Creek slate. Despite being studied for more than 100 y, the exposed section is only recently subdivided into informal members based on identification of sedimentary lithofacies and geologic mapping. This study integrates detrital zircon and paleocurrent analyses with sedimentologic and stratigraphic observations derived from detailed field mapping of the Baraboo and Dake quartzites. Our purpose is twofold: (1) characterize lithofacies of the Baraboo quartzite to interpret the environments of deposition for this unit and (2) evaluate sediment provenance and constrain depositional age. Lithofacies, paleocurrent, and detrital zircon U-Pb analyses of the Baraboo quartzite record fluvial braid plain, eolian, and fluvial-, tide- and wave-influenced deltaic depositional environments with sediments sourced from the north and deposited after 1714 ± 17 Ma. Lithofacies compose two backstepping alluvial to marine successions separated by a thick, laterally continuous coastal dune deposit. North-directed paleocurrents and detrital zircon ages confirm the Dake quartzite is a distinct unit with maximum depositional age of less than 1630.1 ± 8.6 Ma. Deposition of the Dake quartzite reflects basement uplift that postdates deposition of the Baraboo quartzite. The hiatus represented by the unconformity beneath the Dake quartzite is unconstrained and may represent more than 100 My.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"129 1","pages":"1 - 31"},"PeriodicalIF":1.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/713687","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44373895","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: 3

Petrogenesis of the Taishanmiao A-type Granite in the Eastern Qinling Orogenic Belt: Implications for Late Cretaceous Tectonic Transition and Mineralization 东秦岭造山带台山庙A型花岗岩的岩石成因——对晚白垩世构造转换和成矿作用的启示

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2021-01-01 DOI: 10.1086/713726

Jun He, Yue Qi, Xinjie Fan, Fukun Chen

{"title":"Petrogenesis of the Taishanmiao A-type Granite in the Eastern Qinling Orogenic Belt: Implications for Late Cretaceous Tectonic Transition and Mineralization","authors":"Jun He, Yue Qi, Xinjie Fan, Fukun Chen","doi":"10.1086/713726","DOIUrl":"https://doi.org/10.1086/713726","url":null,"abstract":"Numerous late Mesozoic (Late Jurassic to Early Cretaceous) granitic plutons are present along the southern margin of the North China Craton (s-NCC), which belongs to the northernmost tectonic unit of the eastern Qinling orogenic belt. This tectonic unit records multiple tectonothermal and metallogenic events that occurred after continental collision of the North and South China Cratons in the late Early to Middle Triassic. This study reports the zircon U-Pb ages and the whole-rock and apatite geochemical compositions of the Taishanmiao granite, one of the largest late Mesozoic plutons in eastern Qinling. Three phases of this granite, emplaced between ∼125 and ∼113 Ma, are characterized by uniformly high SiO2 and K2O but low CaO, TFe2O3, and MgO contents and enriched Nd isotopic composition with initial εNd values of −13.5 to −12.7. Geochemical features reveal that these are A-type granites derived from partial melting mainly of ancient crust. Temperatures obtained from Ti-in-zircon thermometry and oxygen fugacity (fO2) data indicate that the magma(s) formed at high crystallization temperatures (∼800°–840°C) and fO2 levels (fayalite–magnetite–quartz [FMQ] buffer −1.5 to +1.5). Comparison with neighboring granites, such as the ∼150–130 Ma adakitic Heyu granite and the ∼115 Ma Donggou ore-bearing granite porphyry, implies that the Heyu granite formed from thickened crust and that the Donggou granite porphyry and Taishanmiao granite likely originated from a consistent magma system during the crustal thinning that occurred ∼125–113 Ma, except the porphyry rock was more evolved. This finding implies that their uniform magma chamber could provide sufficient metals and associated materials and even energy for the Donggou Mo deposit.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"129 1","pages":"97 - 114"},"PeriodicalIF":1.8,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/713726","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49377974","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: 0

Deformation Structures in a Large Slump Horizon, Paleoproterozoic Vempalle Formation, Cuddapah Basin, Southern India 印度南部Cuddapah盆地古元古代Vempalle组大滑塌层位的变形构造

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-11-01 DOI: 10.1086/712290

Sayani Khan, T. Majumder, S. Patranabis‐Deb, D. Saha

{"title":"Deformation Structures in a Large Slump Horizon, Paleoproterozoic Vempalle Formation, Cuddapah Basin, Southern India","authors":"Sayani Khan, T. Majumder, S. Patranabis‐Deb, D. Saha","doi":"10.1086/712290","DOIUrl":"https://doi.org/10.1086/712290","url":null,"abstract":"Occurrence of slump folds and associated faults generated by soft-sediment deformation from the Paleoproterozoic Vempalle Formation, southwestern Cuddapah basin, India, is being reported here for the first time. The slump horizon is preserved within a more or less undeformed shallow to deep-water carbonate unit in the Cuddapah basin exposed near Parnapalle village, Andhra Pradesh, India. The stratigraphic framework includes the Gulcheru Quartzite, lowermost unit of the Cuddapah basin succession, deposited in an alluvial to shallow marine shelf environment, and the overlying Vempalle Formation, representing a ramp-type stromatolitic carbonate platform. The synsedimentary sliding along a steepened ramp is evidenced by northeast-verging kink-like folds with wavelength up to 400 m and an overprinting set of thrusts with ramp-flat geometry, fault-cored folds or small break-thrusts showing top-to-southwest displacement, and smaller congruent folds. From the isolated occurrence within a generally undeformed succession, association of structures, and the stratigraphic context, we suggest soft-sediment deformation at the toe of a large (kilometer-scale) slump, with the prevalent bedding-parallel anisotropy exploited for common flexural slip and ramp-flat geometry. In addition, the bedding-parallel slickensides in the Gulcheru Quartzite immediately below the Vempalle Formation indicate a top-to-east-northeast, normal sense of slip representing extensional slip at the slump head. Northeast-verging large folds in the Parnapalle slump horizon possibly represent structures formed during the translation phase of slumping. As the large northeast propagating slump was halted, the backthrust-like structures and associated folds developed at the slump toe.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"128 1","pages":"517 - 534"},"PeriodicalIF":1.8,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/712290","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46174955","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: 0

Radiolarian Biochronology, Detrital Zircon Geochronological and Geochemical Constraints on Provenance and Depositional Environment of Cherts in the Southern Belt of the Western Yarlung Zangbo Suture Zone, Tibet 西藏雅鲁藏布河西部缝合带南带放射虫生物年代学、碎屑锆石年代学及岩质岩物源与沉积环境的地球化学约束

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-11-01 DOI: 10.1086/712185

Fei Liu, D. Lian, Guangying Feng, Zhao-li Li, Xiaolu Niu, Jingsui Yang

{"title":"Radiolarian Biochronology, Detrital Zircon Geochronological and Geochemical Constraints on Provenance and Depositional Environment of Cherts in the Southern Belt of the Western Yarlung Zangbo Suture Zone, Tibet","authors":"Fei Liu, D. Lian, Guangying Feng, Zhao-li Li, Xiaolu Niu, Jingsui Yang","doi":"10.1086/712185","DOIUrl":"https://doi.org/10.1086/712185","url":null,"abstract":"Ophiolites in the southern belt (SB) occur as much larger peridotite massifs compared with those of the northern belt (NB), sporadically overlain by a thin layer of isotropic gabbro in the western part of Yarlung Zangbo suture zone (YZSZ) in Tibet, which in turn is tectonically thrust over a volcanic-sedimentary sequence. Geochemical data and radiolarian fauna of cherts and detrital zircon ages of litho-quartz sandstones in the sequence provide robust constraints to elucidate the stratigraphic and paleo-depositional environments in which these rocks formed. Eight cherts from Purang, Dongbo, Daba Qu, East Daba, and Labuzha massifs in the SB reveal Late Jurassic–Early Cretaceous radiolarians; they are coeval with minimum detrital zircon U-Pb ages of 132 and 149 Ma, respectively, from two litho-quartz sandstones in the northwestern part of Purang massif. Thirty chert samples from five massifs geochemically show that they have high SiO2 contents of 86.51–95.93 wt%, and high mean ratios of Al/(Al+Fe+Mn) ranging from 0.59 to 0.78, indicating a nonhydrothermal, biogenic, and terrigenous origin. Ce/Ce* ratios of cherts range from 0.93 to 1.52, combined with claystone interlayered with radiolarian chert sporadically overlying litho-quartz sandstone and quartzose sandstone, suggesting a continental slope setting. Given the structural and stratigraphic evidences of ophiolites associated with sedimentary strata and no arc-related magmatism in the SB, we propose that SB ophiolites and ophiolitic mélanges represent southward-thrust nappes from the NB.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"128 1","pages":"535 - 562"},"PeriodicalIF":1.8,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/712185","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46924763","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: 3

Young and Old Granulites: A Volatile Connection 年轻和年老的麻粒岩:一个易变的联系

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-09-01 DOI: 10.1086/711026

R. C. Newton

{"title":"Young and Old Granulites: A Volatile Connection","authors":"R. C. Newton","doi":"10.1086/711026","DOIUrl":"https://doi.org/10.1086/711026","url":null,"abstract":"Granulite facies metamorphism of the lower crust has decreased in scale since the Late Archean, but many of its definitive features have persisted: (1) Punctuated, sometimes relatively short-lived, episodes of high-grade metamorphism. These are recorded, in favorably simple cases, by discrete growth rims on zircons. (2) A consistent age gap of a few to several tens of millions of years between juvenile magmatism (crustal accretion) and high-temperature metamorphism. The secondary thermal pulse is an event distinct from primary crustal accretion. (3) Involvement of mineralizing pore fluids of lowered H2O activity, that is, with high CO2 and saline concentrations. Very high oxidation states of some granulites implicate sulfur as an important fluid component. (4) Transcurrent faulting as a conspicuous feature of synmetamorphic deformation. This gives rise to characteristic transposed foliation and lineation. (5) Emplacement of coeval postorogenic K-rich granites at midcrust levels. These features can be rationalized by concepts of modern plate tectonics. High-angle plate collision is succeeded by orogen-parallel transport. This change of plate motion necessarily detaches the underthrust portion of the lithosphere, liberating asthenospheric melts and/or fluids in a postorogenic resurgence. A generation of volatile-rich mafic magmas invades the continental margin; high CO2 and halogen contents cause outgassing and freezing of the magmas at depth. Liberated volatiles effect granulite facies metamorphism by leaching H2O and lithophile elements, importantly K, and transporting these components and heat upward. Extensive melting of the lower crust is inhibited by the low H2O activity of saline-carbonic pore fluids at high pressure. Melting of orthogneiss and supracrustal rocks occurs at midcrust levels by increase of H2O activity as pressure on alkali chloride solutions falls below 0.6–0.5 GPa. The foregoing hypothesis is an alternative to the classical view that granite results from fluid-absent partial melting of, and extraction from, the lower crust, leaving granulites.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"128 1","pages":"395 - 413"},"PeriodicalIF":1.8,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/711026","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45773286","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

Integrating Petrography, X-Ray Fluorescence, and U-Pb Detrital Zircon Geochronology to Interpret Provenance of the Mississippian Hartselle Sandstone, USA 结合岩石学、x射线荧光和U-Pb碎屑锆石年代学解释美国密西西比期Hartselle砂岩物源

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-06-24 DOI: 10.1086/709700

Jennifer N. Gifford, B. Platt, L. D. Yarbrough, A. O’Reilly, Mohammed Al Harthy

{"title":"Integrating Petrography, X-Ray Fluorescence, and U-Pb Detrital Zircon Geochronology to Interpret Provenance of the Mississippian Hartselle Sandstone, USA","authors":"Jennifer N. Gifford, B. Platt, L. D. Yarbrough, A. O’Reilly, Mohammed Al Harthy","doi":"10.1086/709700","DOIUrl":"https://doi.org/10.1086/709700","url":null,"abstract":"The Chesterian (Mississippian) Hartselle Sandstone is a tar sand exposed in the Black Warrior Basin and southern Appalachian fold belt in northern Mississippi and Alabama. Previous studies disagree about the delivery direction and relative contributions of sediment from the cratonic interior, the Appalachians, and the Ouachitas. The goal of this research is to investigate lateral trends in sedimentary and geochemical properties to provide new details about the provenance of the Hartselle. Samples were collected along a west-to-east transect and analyzed using petrography, X-ray fluorescence (XRF) geochemistry, and U-Pb detrital zircon (DZ) geochronology. Point counting indicated a major cratonic interior source with a minor recycled orogen signal. Sillimanite in the easternmost sample narrows down the potential Appalachian sources to areas of high-grade metamorphism. Petrographic observations suggest both western and eastern sources. The XRF results showed high concentrations of Ti and Mo in the westernmost sample, suggestive of a nearby terrigenous source. All of the samples had similar U-Pb DZ age distributions except for the easternmost sample, which had statistically higher proportions of Paleozoic- and Archean-aged grains (Kolmogorov-Smirnov test: p < .02). For the first time, Eoarchean and Paleoarchean grains were found in the Hartselle, indicating a likely sediment source from the Minnesota River Valley gneisses of the Superior Craton prior to Grenvillian overprinting. Based on integration of all data, we conclude that a large fluvial system draining the continental interior provided a substantial volume of sediment from the northwest. At the same time, a more dispersed drainage basin associated with the Appalachian front contributed recycled orogenic material from the northeast.","PeriodicalId":54826,"journal":{"name":"Journal of Geology","volume":"128 1","pages":"337 - 370"},"PeriodicalIF":1.8,"publicationDate":"2020-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/709700","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44903727","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: 4

From Cosmic Explosions to Terrestrial Fires? A Reply 从宇宙爆炸到陆地火灾？答覆

IF 1.8 4区地球科学

Journal of Geology Pub Date : 2020-06-17 DOI: 10.1086/709751

A. Melott, B. Thomas

引用次数: 1