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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 65 (1981)

Issue: 5. (May)

First Page: 1011

Last Page: 1011

Title: Mesozoic and Cenozoic Paleogeography: ABSTRACT

Author(s): A. M. Zieglar, R. K. Bambach, S. F. Barrett

Article Type: Meeting abstract


A series of reconstructions showing land-sea relations, sedimentary facies, and volcanic types has been drawn. Continental orientations were determined using paleomagnetic, climatic, biogeographic, and sea-floor anomaly data. The main differences between these and existing maps are seen in south Asia. Here, Late Triassic sutures, involving Indochina, South China, and North China, indicate that Pangea did not form until this time. Paleoclimatic indicators associated with these south Asian blocks would place them in the tropics in the Triassic rather than the temperate zone as suggested by most published maps. Another innovation in the maps is the palinspastic restoration of the zone between India and the Tarim basin. Published paleogeographic maps show a 1,500 km-wide ocea between Indian and Asia in the late Eocene, the time that lithofacies and biogeographic data indicate that they were in contact. Present crustal thicknesses across the Himalayas and the Tibetan Plateau are double the norm, and so by "unthrusting" the Himalayas, and "unfolding" Tibet, we have constructed a series of maps that show the Asian blocks in contact at the appropriate times. All of the above changes result in an areally restricted Tethyan seaway. The effect of crustal foreshortening in the Tertiary may help to explain the extreme lowering of sea level during this time. The telescoping of continental crust would result in wider ocean basins at the present than at any time since the end of the Permian. This would have the effect of draining the epeiric seas.

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