Proterozoic-Cambrian history of Dronning Maud Land in the context of Gondwana assembly
Proterozoic-Cambrian history of Dronning Maud Land in the context of Gondwana assembly
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冈瓦纳大陆组装背景下德隆莫德地的元古代-寒武纪历史
DOI：
10.1144/gsl.sp.2003.206.01.13
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
J. Jacobs
中科院分区：
文献类型：
--
作者：
W. Bauer;R. Thomas;J. Jacobs
Dronning Maud陆块是一个被中元古代沉积岩和岩浆岩覆盖的太古宙克拉通碎片，被晚中元古代变质带包围。在变质带内证实了中元古代末期和新元古代晚期-寒武纪（泛非）的构造热事件。在龙茅地西部，在约1.1 Ga时，一个幼年的中元古代基底被吸积到克拉通中。通过对Dronning Maud地块中部片麻岩进行锆石SHRIMP定年，发现了中元古代的岩石，随后出现了一个缺乏年代学资料的长间断期，确定了泛非洲时代的角闪岩-麻粒岩相变质作用和同构造花岗岩类侵位作用。在此造山运动中，较老的构造在左旋坳陷变形下完全叠加，形成了东南极造山带以海岸平行为主的构造构造。将南极洲重新置于冈瓦纳的位置，东南极造山带在东非继续向北，成为东非造山带，而沿沙克尔顿山脉与东南极洲太平洋边缘的罗斯造山带相连。东南极洲-东非造山带是由于莫桑比克洋的闭合和西冈瓦纳与东冈瓦纳的碰撞而形成的，即西Dronning Maud陆是西冈瓦纳的一部分。在这次碰撞中，岩石圈地幔可能分层，使软流圈进入大陆地壳的底部，并为Dronning Maud大陆中部大量的、典型的无水泛非花岗岩类产生热量。
Abstract Dronning Maud Land contains a fragment of an Archaean craton covered by sedimentary and magmatic rocks of Mesoproterozoic age, surrounded by a Late Mesoproterozoic metamorphic belt. Tectonothermal events at the end of the Mesoproterozoic and in Late Neoproterozoic-Cambrian times (Pan-African) have been proved within the metamorphic belt. In western Dronning Maud Land a juvenile Mesoproterozoic basement was accreted to the craton at c. 1.1 Ga. Mesoproterozoic rocks were also detected by zircon SHRIMP dating of gneisses in central Dronning Maud Land, followed by a long hiatus for which geochronological data are lacking, an amphibolite to granulite facies metamorphism and syntectonic granitoid emplacement of Pan-African age have been dated. During this orogeny older structures were completely overprinted in a sinistral tranpressive deformation regime, leading to the mainly coast-parallel tectonic structures of the East Antarctic Orogen. Putting Antarctica back in its Gondwana position, the East Antarctic Orogen continues northward in East Africa as the East African Orogen, whereas a connection to the marginal Ross Orogen at the Pacific margin of East Antarctica is suggested along the Shackleton Range. The East Antarctic-East African Orogen resulted from closure of the Mozambique Ocean and collision of West and East Gondwana, i.e. western Dronning Maud Land was part of West Gondwana. During this collision the lithospheric mantle probably delaminated, allowing the asthenosphere to underplate the continental crust and producing heat for the voluminous, typically anhydrous, Pan-African granitoids of central Dronning Maud Land.