The Upper Carboniferous-Lower Permian （Upper Pennsylvanian-Asselian） Tobra Formation is exposed in the Salt and Trans Indus ranges of Pakistan. The formation exhibits an alluvial plain （alluvial fan-piedmont alluvi...The Upper Carboniferous-Lower Permian （Upper Pennsylvanian-Asselian） Tobra Formation is exposed in the Salt and Trans Indus ranges of Pakistan. The formation exhibits an alluvial plain （alluvial fan-piedmont alluvial plain） facies association in the Salt Range and Khisor Range. In addition, a stream flow facies association is restricted to the eastern Salt Range. The alluvial plain facies association is comprised of clast-supported massive conglomerate （Gmc）, diamictite （Dm） facies, and massive sandstone （Sm） iithofacies whereas the stream flow-dominated alluvial plain facies association includes fine-grained sandstone and sUtstone （Fss）, fining upwards pebbly sandstone （Sf）, and massive mudstone （Fro） lithofacies. The lack of glacial signatures （particularly glacial grooves and striations） in the deposits in the Tobra Formation, which are, in contrast, present in their time-equivalent and palaeogeographically nearby strata of the Arabian peninsula, e.g. the Al Khlata Formation of Oman and Unayzah B member of the Sandi Arabia, suggests a pro-to periglacial, i.e. glaciofluvial depositional setting for the Tobra Formation. The sedimentology of the Tobra Formation attests that the Salt Range, Pakistan, occupied a palaeogeographic position just beyond the maximum glacial extent during Upper Pennsylvanian-Asselian time.展开更多
The sedimentology of the Northwestern Sudan consists of lower, middle and upper cycles. The lower and upper cycles are composed of intercalated fluvial and shallow marine facies, whereas the middle cycle consists enti...The sedimentology of the Northwestern Sudan consists of lower, middle and upper cycles. The lower and upper cycles are composed of intercalated fluvial and shallow marine facies, whereas the middle cycle consists entirely of fluvial and glaciofluvial facies. The petrographic analysis shows that the lower and upper cycles consist of quartz and lithic arenite sandstones, whereas the middle cycle consists of arkosic and lithic arenite sandstones. The lower and upper cycle sandstones reflect derivation mainly from recycled orogens with minor contribution from craton interior provenances. However, the middle cycle sandstones indicate derivation from basement uplift, transitional and mainly recycled orogens provenances.展开更多
基金the Higher Education Commission of Pakistan's National Research Program for Universities(NRPU) grant to Dr.Irfan U.Jan,principal investigator on the project via grant number 20-2706
文摘The Upper Carboniferous-Lower Permian （Upper Pennsylvanian-Asselian） Tobra Formation is exposed in the Salt and Trans Indus ranges of Pakistan. The formation exhibits an alluvial plain （alluvial fan-piedmont alluvial plain） facies association in the Salt Range and Khisor Range. In addition, a stream flow facies association is restricted to the eastern Salt Range. The alluvial plain facies association is comprised of clast-supported massive conglomerate （Gmc）, diamictite （Dm） facies, and massive sandstone （Sm） iithofacies whereas the stream flow-dominated alluvial plain facies association includes fine-grained sandstone and sUtstone （Fss）, fining upwards pebbly sandstone （Sf）, and massive mudstone （Fro） lithofacies. The lack of glacial signatures （particularly glacial grooves and striations） in the deposits in the Tobra Formation, which are, in contrast, present in their time-equivalent and palaeogeographically nearby strata of the Arabian peninsula, e.g. the Al Khlata Formation of Oman and Unayzah B member of the Sandi Arabia, suggests a pro-to periglacial, i.e. glaciofluvial depositional setting for the Tobra Formation. The sedimentology of the Tobra Formation attests that the Salt Range, Pakistan, occupied a palaeogeographic position just beyond the maximum glacial extent during Upper Pennsylvanian-Asselian time.
文摘The sedimentology of the Northwestern Sudan consists of lower, middle and upper cycles. The lower and upper cycles are composed of intercalated fluvial and shallow marine facies, whereas the middle cycle consists entirely of fluvial and glaciofluvial facies. The petrographic analysis shows that the lower and upper cycles consist of quartz and lithic arenite sandstones, whereas the middle cycle consists of arkosic and lithic arenite sandstones. The lower and upper cycle sandstones reflect derivation mainly from recycled orogens with minor contribution from craton interior provenances. However, the middle cycle sandstones indicate derivation from basement uplift, transitional and mainly recycled orogens provenances.
