The Carboniferous can be divided into four series in the Dianqiangui basin and its adjacent areas, Southwest China： the Yanguanian series, the Datangian series, the Weiningian series and the Mapingian series. The Map...The Carboniferous can be divided into four series in the Dianqiangui basin and its adjacent areas, Southwest China： the Yanguanian series, the Datangian series, the Weiningian series and the Mapingian series. The Maping Formation, traditionally used as the lithostraUgraphic unit of the Upper Carboniferous, became an inter-system unit from the Carboniferous to the Permian. Thus, the top part of the Carboniferous and the bottom part of the Permian （Chuaushanian series） constitute a third-order sequence in the Dianqiangui basin and its adjacent areas. In the study area, the Carboniferous system and the Chuanshanian series of the Permian constitute a second-order sequence that can be subdivided into 6 third-order sequences. The bottom boundary of this second-order sequence is an unconformity formed in the principal episode of the Ziyun movement （the second episode）, and the top boundary is also an unconformity formed in the principal episode of the Qiangui movement （the second episode）. In different paleogeographical backgrounds, the strata from the Carboniferous to the Permian Chuanshanian epoch are marked by different sedimentary features. For example, coal measures and more dolomitic strata are developed in the attached platform; carbonate rocks mainly constitute the isolated platform strata; the inter-platform ditch strata are mainly composed of dark and fine sediments. Therefore, third-order sequences with different architectures of sedimentary-facies succession are formed in different paleogeographical backgrounds. Although the third-order sequences are different in the architecture of sedimentary-succession in space, the processes of their depositional environmental changes due to the third-order relative sea-level changes are simultaneous. Biostratigraphically, the surfaces of the thirdorder sequences can be correlated and traced in space; the framework of sequence stratigraphy from the Carboniferous to the Chuanshanian epoch of the Permian can be established in the Dianqiangui basin and its adjacent areas in terms of two types of facies-changing surfaces as well as two kinds of diachronism in stratigraphic records. The sequence-stratigraphic subdivisions from the Carboniferous to the Permian Chuanshanian epoch in the study area show that the duration of third-order sequences, formed in the convergent period of Pangea, is more than 10 Ma. This could reflect the elementary feature that the period of sea-level change cycles formed in a relatively quiet period of tectonic action is more than 10 Ma. And this succession shows a marked cyclicity which is supposed to be the low-latitude response to the Gondwanan glaciation in the southern hemisphere.展开更多
The Beyşehir-Hoyran Nappes,one of the tectonostratigraphic units of the Taurides,are thought to be originated from the Izmir-Ankara Ocean(northern branch of Neotethys).In this study,Late Paleozoic rock units from the ...The Beyşehir-Hoyran Nappes,one of the tectonostratigraphic units of the Taurides,are thought to be originated from the Izmir-Ankara Ocean(northern branch of Neotethys).In this study,Late Paleozoic rock units from the blocks of Beyşehir-Hoyran Nappes were studied in detail using foraminiferal assemblages in two different locations from the southwest of Karaman City(southern Turkey).In both places,blocks/slices and pebbles of various origins are embedded within a highly sheared matrix of Late Cretaceous Age,and the whole unit can be regarded as a sedimentary mélange.The ages of the blocks from the southwest of Karaman City range from the Late Serpukhovian(Late Mississippian)to Late Capitanian(Middle Permian)with some depositional breaks(e.g.,Bashkirian,Kasimovian).Combined with the previous data from the Mersin Mélange,which also include the remnants of the Beyşehir-Hoyran Nappes,our new findings suggest that a shallowing-upward sequence,characterized by a shallow water environment with foraminifera-bearing limestones,was deposited over the Tournaisian pelagic sequence in the Beyşehir-Hoyran Nappes till the Early Moscovian(Early Middle Pennsylvanian).This shallowing-upward sequence in the Beyşehir-Hoyran Nappes could be related to the Late Paleozoic Glaciation on the Gondwana supercontinent(Glacial Ⅱ),which resulted in a sea-level drop and deposition of platform carbonates during the Viséan–Early Moscovian(Middle Mississippian to Early Middle Pennsylvanian)time interval.The absence of the main part of the Middle-Upper Pennsylvanian deposits(continental phase during the Middle Moscovian–Middle Gzhelian)in the Beyşehir-Hoyran Nappes can be mainly attributed to the occurrence of a mantle plume and partially to the effect of Late Paleozoic Gondwanan Glaciation(Glacial Ⅲ).Progressive uplifting by the buoyant mantle plume material has resulted in rifting at the center of the basin where the Beyşehir-Hoyran Nappes have deposited.The rifting process led to tectonic destabilization of the platform in the basin,causing accumulation of the Upper Gzhelian(uppermost Pennsylvanian)detrital limestone with broken and abraded foraminiferal shells.Following this,deep basinal conditions prevailed during the Late Asselian–Kungurian(Early Permian),as revealed in the Mersin Mélange,where radiolarian cherts are associated with continental within-plate lavas of extreme incompatible trace element enrichment.Similar processes were responsible for the continual deposition of detrital limestones in the same basin until the end of Late Capitanian(Middle Permian).Based on all these,the uplifting process followed by rift-related volcanic rocks and detrital limestones can be interpreted as the opening of the Izmir-Ankara Ocean(northern Neotethys).展开更多
文摘The Carboniferous can be divided into four series in the Dianqiangui basin and its adjacent areas, Southwest China： the Yanguanian series, the Datangian series, the Weiningian series and the Mapingian series. The Maping Formation, traditionally used as the lithostraUgraphic unit of the Upper Carboniferous, became an inter-system unit from the Carboniferous to the Permian. Thus, the top part of the Carboniferous and the bottom part of the Permian （Chuaushanian series） constitute a third-order sequence in the Dianqiangui basin and its adjacent areas. In the study area, the Carboniferous system and the Chuanshanian series of the Permian constitute a second-order sequence that can be subdivided into 6 third-order sequences. The bottom boundary of this second-order sequence is an unconformity formed in the principal episode of the Ziyun movement （the second episode）, and the top boundary is also an unconformity formed in the principal episode of the Qiangui movement （the second episode）. In different paleogeographical backgrounds, the strata from the Carboniferous to the Permian Chuanshanian epoch are marked by different sedimentary features. For example, coal measures and more dolomitic strata are developed in the attached platform; carbonate rocks mainly constitute the isolated platform strata; the inter-platform ditch strata are mainly composed of dark and fine sediments. Therefore, third-order sequences with different architectures of sedimentary-facies succession are formed in different paleogeographical backgrounds. Although the third-order sequences are different in the architecture of sedimentary-succession in space, the processes of their depositional environmental changes due to the third-order relative sea-level changes are simultaneous. Biostratigraphically, the surfaces of the thirdorder sequences can be correlated and traced in space; the framework of sequence stratigraphy from the Carboniferous to the Chuanshanian epoch of the Permian can be established in the Dianqiangui basin and its adjacent areas in terms of two types of facies-changing surfaces as well as two kinds of diachronism in stratigraphic records. The sequence-stratigraphic subdivisions from the Carboniferous to the Permian Chuanshanian epoch in the study area show that the duration of third-order sequences, formed in the convergent period of Pangea, is more than 10 Ma. This could reflect the elementary feature that the period of sea-level change cycles formed in a relatively quiet period of tectonic action is more than 10 Ma. And this succession shows a marked cyclicity which is supposed to be the low-latitude response to the Gondwanan glaciation in the southern hemisphere.
基金grateful to Hacettepe University,Scientific Research Project Department(No.FBA-2018-16915)for providing financial support to this research.
文摘The Beyşehir-Hoyran Nappes,one of the tectonostratigraphic units of the Taurides,are thought to be originated from the Izmir-Ankara Ocean(northern branch of Neotethys).In this study,Late Paleozoic rock units from the blocks of Beyşehir-Hoyran Nappes were studied in detail using foraminiferal assemblages in two different locations from the southwest of Karaman City(southern Turkey).In both places,blocks/slices and pebbles of various origins are embedded within a highly sheared matrix of Late Cretaceous Age,and the whole unit can be regarded as a sedimentary mélange.The ages of the blocks from the southwest of Karaman City range from the Late Serpukhovian(Late Mississippian)to Late Capitanian(Middle Permian)with some depositional breaks(e.g.,Bashkirian,Kasimovian).Combined with the previous data from the Mersin Mélange,which also include the remnants of the Beyşehir-Hoyran Nappes,our new findings suggest that a shallowing-upward sequence,characterized by a shallow water environment with foraminifera-bearing limestones,was deposited over the Tournaisian pelagic sequence in the Beyşehir-Hoyran Nappes till the Early Moscovian(Early Middle Pennsylvanian).This shallowing-upward sequence in the Beyşehir-Hoyran Nappes could be related to the Late Paleozoic Glaciation on the Gondwana supercontinent(Glacial Ⅱ),which resulted in a sea-level drop and deposition of platform carbonates during the Viséan–Early Moscovian(Middle Mississippian to Early Middle Pennsylvanian)time interval.The absence of the main part of the Middle-Upper Pennsylvanian deposits(continental phase during the Middle Moscovian–Middle Gzhelian)in the Beyşehir-Hoyran Nappes can be mainly attributed to the occurrence of a mantle plume and partially to the effect of Late Paleozoic Gondwanan Glaciation(Glacial Ⅲ).Progressive uplifting by the buoyant mantle plume material has resulted in rifting at the center of the basin where the Beyşehir-Hoyran Nappes have deposited.The rifting process led to tectonic destabilization of the platform in the basin,causing accumulation of the Upper Gzhelian(uppermost Pennsylvanian)detrital limestone with broken and abraded foraminiferal shells.Following this,deep basinal conditions prevailed during the Late Asselian–Kungurian(Early Permian),as revealed in the Mersin Mélange,where radiolarian cherts are associated with continental within-plate lavas of extreme incompatible trace element enrichment.Similar processes were responsible for the continual deposition of detrital limestones in the same basin until the end of Late Capitanian(Middle Permian).Based on all these,the uplifting process followed by rift-related volcanic rocks and detrital limestones can be interpreted as the opening of the Izmir-Ankara Ocean(northern Neotethys).
