Early and Middle Proterozoic History of the Great Lakes Area, North America
Early and Middle Proterozoic History of the Great Lakes Area, North America
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北美五大湖区早元古代和中元古代历史
DOI：
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发表时间：
1976
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通讯作者：
W. R. Schmus
中科院分区：
文献类型：
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作者：
W. R. Schmus
两个主要的上地壳层序，安大略省的休伦超群，密歇根州和明尼苏达州的马奎特山脉超群和Animikie群，位于太古宙基底之上。这些序列的年龄分别约为2200 ~ 2300 Ma和1900 ~ 2000 Ma。早元古代的主要构造事件是“Penokean造山运动”，发生在1850-1900 Ma之前，包括变形、高级别区域变质、挤压和侵入性火成岩活动。随后是流纹岩、火成岩火山岩的形成，并在1790 Ma前形成了伴生花岗岩。1650 ~ 1700 Ma前，整个地区经历了低等级的区域变质作用，1500 Ma前，造山石英二长岩（部分为拉帕奇岩）、岩体侵位。晚元古代的Grenville和Keweenawan事件代表了该地区最年轻的主要前寒武纪活动。在苏必利斯省太古宙克拉通南缘，有古宙造山活动的岩石，代表了早元古代克拉通-边缘造山活动。与Penokean造山运动相关的岩石类型和构造的分布以及与北美太古代克拉通边缘类似的造山带的分布表明，这些造山带可能是由类似于现代板块构造的过程形成的，尽管目前的数据还远远没有定论。
Two major supracrustal sequences, the Huronian Supergroup in Ontario and the Marquette Range Supergroup and Animikie Group of Michigan and Minnesota, overlie an Archean basement. These sequences are about 2200—2300 Ma and 1900-2000 Ma old respectively. The major Early Proterozoic tectonic event is the ‘Penokean Orogeny’, which occurred about 1850-1900 Ma ago and included deformation, high-grade regional metamorphism, and extrusive and intrusive igneous activity. This was followed by formation of rhyolitic, ignimbritic volcanic rocks and emplacement of associated granites about 1790 Ma ago. The entire region was subsequently subjected to low-grade regional metamorphism 1650-1700 Ma ago, followed by emplacement of anorogenic quartz-monzonite, in part rapakivi, plutons 1500 Ma ago. Late Proterozoic Grenville and Keweenawan events represent the youngest major Precambrian activity in the region. The rocks involved in the Penokean Orogeny lie along the southern margin of the Archean craton of the Superior Province and are interpreted as representing Early Proterozoic cratonic-margin orogenic activity. The distribution of rocks types and structures associated with the Penokean Orogeny and with similar orogenic belts along the margin of the Archean craton of North America suggest that these orogenic belts may have formed as a result of processes similar to modern plate tectonics, although the data are far from conclusive at present.