Collaborative Research: The Neoproterozoic and Cambrian of the Tethyan Himalaya: A Test of Models of Core Gondwanan Construction

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EAR 9980376 MyrowEAR 9980426 HughesCollaborative Research: THE NEOPROTEROZOIC AND CAMBRIAN OF THE TETHYAN HIMALAYA: A TEST OF MODELS OF CORE GONDWANAN CONSTRUCTIONThe nature and timing of the assembly of core Gondwanaland remains a matterof vigorous debate. The traditional view is that East Gondwana, consistingof India, Australia and Antarctica collided with the combined Africancratons (Kalahari and Congo) as one block sometime during the lateNeoproterozoic. An alternative model suggests that the accretion of EastGondwana to the African craton was a two part process. In this model, Indiabroke off from Australia and Antarctic, swept across the Mozambique Ocean,and collided with the African craton at approximately 680 Ma. This waspurportedly followed sometime later by collision of Australia/Antarcticaaround 550 to 530 Ma. Our study of the Tethyan Himalaya will test tectonicmodels of the assembly of core Gondwanaland using a combined stratigraphic,macrofaunal and sedimentological approach. Of primary importance is thestratigraphic signature of sediment input from adjacent orogenic belts. Arecord of major increases of siliclastic sediment, with abrupt changes inpaleocurrents would accompany orogenesis. A key component of the proposedmodels is that they have predictable patterns of detrital zircon ages. ALate Cambrian-Early Ordovician tectonic event is recorded in the TethyanHimalaya and in other places in East Gondwanaland. The nature of this eventis unclear, but two possibilities include: (1) it represents a somewhatdelayed expression of the Australia/Antarctica collision in the two-stagemodel, or (2) it represents the docking of an outboard microcontinent(e.g., the Lhasa Block of Tibet) subsequent to the formation of coreGondwanaland. The biostratigraphic patterns of trilobites provide the basisof testable predictions of these hypotheses. In the first case, we expectto find a stratigraphic increase in similarity in faunas between India andthe rest of East Antarctica throughout the Cambrian. If faunal similaritywith the rest of East Gondwana was constant throughout thetrilobite-bearing Cambrian, we may infer that Gondwanan construction wascomplete prior to 520 Ma. In addition, if the ~500 Ma tectonic event in theTethyan Himalaya records microcontinental collision, then theidentification of the outboard terrane may be approached throughbiogeographic patterns established in this study. Myrow's RUI proposal willinvolve undergraduates at Colorado College as junior collaborators in allcomponents of the research. This will provide a much-needed opportunity forstudents to experience scientific research in diverse geographical andcultural environments. A key aspect of this proposal is the close researchcollaboration with Indian and Chinese scientists.