RUI: COLLABORATIVE RESEARCH: The Neoproterozoic and Cambrian of the Tethyan Himalaya: A Test of Models of Core Gondwanan Construction

9980376-9980426休斯合作研究：特提斯喜马拉雅新元古代和寒武纪：冈德瓦南岩芯构造模型的测试冈湾岩芯组装的性质和时间仍然是一个激烈辩论的问题。传统观点认为，由印度、澳大利亚和南极洲组成的东冈瓦那在新元古代晚期的某个时候与合并的非洲大陆(卡拉哈里和刚果)作为一个地块相撞。另一种模型表明，东冈瓦那对非洲克拉通的吸积是一个分两部分的过程。在这个模型中，印度从澳大利亚和南极分离出来，横扫莫桑比克大洋，在大约680 Ma时与非洲克拉通相撞。据称，在此之后的一段时间，澳大利亚和南极洲在550至530 Ma之间发生了碰撞。我们对特提斯喜马拉雅的研究将使用地层学、大型动物群和沉积学相结合的方法来检验冈瓦核心组装的构造模型。最重要的是邻近造山带输入的沉积物的地层特征。伴随着造山作用，硅质碎屑沉积的主要增加和古水流的突变将被记录下来。提出的模型的一个关键组成部分是它们具有可预测的碎屑锆石年龄模式。阿拉特寒武纪-早奥陶世构造事件记录在特提亚喜马拉雅和东冈瓦的其他地方。这一事件的性质尚不清楚，但有两种可能性：(1)它代表了澳大利亚/南极洲碰撞在两阶段模式中的某种延迟表达；(2)它代表了在核心冈瓦大陆形成后，外部微大陆(如西藏拉萨地块)的对接。三叶虫的生物地层学模式为这些假说提供了可检验的预测基础。在第一个案例中，我们预计会发现整个寒武纪印度和东南极其他地区的动物群在地层上的相似性有所增加。如果在整个含三闪石寒武纪，与东冈瓦那其他地区的动物群相似性是恒定的，我们可以推断冈德瓦构造在520 Ma之前就完成了。此外，如果特提斯喜马拉雅约500 Ma的构造事件记录了微陆碰撞，那么可以通过本研究建立的生物地理模式来探讨外侧地体的识别。Myrow的Rui计划将让科罗拉多学院的本科生作为初级合作者参与这项研究的所有部分。这将为学生在不同的地理和文化环境中体验科学研究提供一个亟需的机会。这一提议的一个关键方面是与印度和中国科学家的密切研究合作。

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.