Basin analysis in polymetamorphic terranes: An example from east Antarctica
Basin analysis in polymetamorphic terranes: An example from east Antarctica
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DOI：
10.1016/j.precamres.2013.03.015
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发表时间：
2013-07
影响因子：
3.8
通讯作者：
J. Halpin;N. Daczko;G. Clarke;Kathleen R. Murray
中科院分区：
文献类型：
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作者：
J. Halpin;N. Daczko;G. Clarke;Kathleen R. Murray
东南极肯普陆和麦克罗伯逊陆麻粒岩相副片麻岩中碎屑锆石和变质锆石的U-Pb和Lu-Hf同位素特征，区分了两个广泛的前寒武纪盆地：（1）沉积于c. 2570 Ma和C. 2500- 2430 Ma，横跨肯普陆，与恩德比陆相邻的纳皮耶杂岩中的相应副片麻岩相邻;（2）晚中元古代盆地，沉积于c. 1110- 1080 Ma，位于延伸到肯普地东部的麦克罗伯逊地，该地区还包括目前暴露于印度东高止山脉省和南极洲东部的普拉茨湾地区的岩石。一个不整合面分隔了白垩纪和中元古代的沉积包，位于斯蒂尔韦尔山附近。向东增加的比例零碎碎屑锆石在年轻的包反映接近晚中元古代火山源。中元古界盆地可能是在Rodinia板块组装期间的弧后环境中，沿着沿着安第斯型边缘向印度-南极克拉通发展的。c时锆石的广泛溶解。肯普和麦克罗伯逊陆块Rayner造山作用期间的990- 940 Ma在很大程度上排除了通过碎屑年代学进行传统盆地分析的可能性，但深熔作用后沉淀的变质锆石的Hf同位素比值提供了一个均一化的特征，相当于一个块体岩石模型年龄，可用作地层代用资料。这种方法捕捉“隐藏”的物源信息，使复杂的高品位砂岩的岩石地层对比。
U–Pb and Lu–Hf isotopic signatures of detrital and metamorphic zircon in granulite facies paragneiss from Kemp and MacRobertson lands, east Antarctica, distinguish two extensive Precambrian basins: (1) an Archaean basin deposited between c. 2570Ma and c. 2500–2430Ma, which extended across Kemp Land contiguous with equivalent paragneiss in the adjacent Napier Complex in Enderby Land; and (2) a late Mesoproterozoic basin deposited after c. 1110–1080Ma in MacRobertson Land that extends into eastern Kemp Land, which also incorporates rocks currently exposed in the Eastern Ghats Province of India and the Prydz Bay region of east Antarctica. An unconformity that separates the Archaean and Mesoproterozoic sedimentary packages is near the Stillwell Hills. An eastward increase in the proportion of fragmentary detrital zircon in the younger package reflects proximity to late Mesoproterozoic volcanic sources. The Mesoproterozoic basin likely developed along an Andean-type margin to the Indo-Antarctic craton, possibly in a back-arc setting during the assembly of Rodinia. The widespread dissolution of zircon at c. 990–940Ma during Rayner orogenesis in Kemp and MacRobertson lands largely precludes a traditional basin analysis via detrital geochronology, but the Hf isotopic ratio of metamorphic zircon precipitated following anatexis provides a homogenised signature, equivalent to a bulk-rock model age, which can be used as a stratigraphic proxy. This approach captures “hidden” provenance information to enable lithostratigraphic correlation in complex high-grade terranes.