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 Anthropocene defined as an epoch/series within the Geological Time Scale,and with an isochronous inception in the mid-20th century,would both utilize the rich array of stratigraphic signals associated with the Gre...The Anthropocene defined as an epoch/series within the Geological Time Scale,and with an isochronous inception in the mid-20th century,would both utilize the rich array of stratigraphic signals associated with the Great Acceleration and align with Earth System science analysis from where the term Anthropocene originated.It would be stratigraphically robust and reflect the reality that our planet has far exceeded the range of natural variability for the Holocene Epoch/Series which it would terminate.An alternative,recently advanced,time-transgressive‘geological event’definition would decouple the Anthropocene from its stratigraphic characterisation and association with a major planetary perturbation.We find this proposed anthropogenic‘event’to be primarily an interdisciplinary concept in which historical,cultural and social processes and their global environmental impacts are all flexibly interpreted within a multi-scalar framework.It is very different from a stratigraphic-methods-based Anthropocene epoch/series designation,but as an anthropogenic phenomenon,if separately defined and differently named,might be usefully complementary to it.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.
基金support from a Natural Sciences and Engineering Research Council of Canada Discovery Grant.
文摘The Anthropocene defined as an epoch/series within the Geological Time Scale,and with an isochronous inception in the mid-20th century,would both utilize the rich array of stratigraphic signals associated with the Great Acceleration and align with Earth System science analysis from where the term Anthropocene originated.It would be stratigraphically robust and reflect the reality that our planet has far exceeded the range of natural variability for the Holocene Epoch/Series which it would terminate.An alternative,recently advanced,time-transgressive‘geological event’definition would decouple the Anthropocene from its stratigraphic characterisation and association with a major planetary perturbation.We find this proposed anthropogenic‘event’to be primarily an interdisciplinary concept in which historical,cultural and social processes and their global environmental impacts are all flexibly interpreted within a multi-scalar framework.It is very different from a stratigraphic-methods-based Anthropocene epoch/series designation,but as an anthropogenic phenomenon,if separately defined and differently named,might be usefully complementary to it.
