The early Neoproterozoic sedimentary Succession B of northwestern Laurentia: Correlations and paleogeographic significance
The early Neoproterozoic sedimentary Succession B of northwestern Laurentia: Correlations and paleogeographic significance
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劳伦西亚西北部新元古代早期沉积演替B：相关性及古地理意义
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
G. M. Young
中科院分区：
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作者：
R. Rainbird;C. Jefferson;G. M. Young
北美古陆（劳伦提斯）的中元古代-新元古代地层记录包括三个以不整合面为界的沉积序列，从最古老到最年轻分别称为A、B和C。最近和正在进行的层序B的详细地层学研究，沿着改进的地质年代学，允许扩展和完善现有的加拿大西北部和阿拉斯加的对比方案。层序B层包括阿蒙森盆地的谢勒超群、麦肯齐山脉褶皱带的麦肯齐山脉超群、韦尔内克山脉内层的Pinguicula群、奥格尔维山脉内层的Fifteenmile群和塔通杜克山脉内层的下廷迪尔群。位于阿拉斯加布鲁克斯山脉东北部的卡塔克图鲁克白云岩，根据台地特征、地质年代学和推断的古地理亲缘关系，被纳入层序B。层序B的区域岩石地层对比框架是建立在对四个不同岩石地层组合的认识上的：两个厚的叠层石台地状碳酸盐组合被两个主要的陆上硅质岩组合分开。上部石英砂岩组合中碎屑锆石的年代学结果支持了这一对比，表明最大年龄为约10000年。继承B的下部为1000 Ma。这些岩石被解释为西北走向（现在的坐标）的新元古代早期盆地边缘海角（Amundsen-Ogilvie-麦肯齐平台）的残余物，在劳伦大陆西北边缘的克拉通盆地内发育。北美西北部新元古代地层记录与其他大陆的同时代地层有着惊人的相似性，特别是在澳大利亚中部和南部的Amadeus盆地和阿德莱德褶皱带。新元古代超大陆的重建将古澳大利亚的东缘与劳伦大陆的西缘并置在一起，当时这些地层正在沉积。因此，阿蒙森-奥格尔维-麦肯齐地台可能代表了一个大型克拉通内盆地的一部分（边缘），该盆地在最后元古代随着超大陆的分裂而裂陷。这一假设为未来的层序地层学、化学地层学、生物地层学、古地磁学和地质年代学的比较提供了一个模板，并对这两个地区的预测性经济地质学产生了影响。群和超群的大写表示根据国际地层代码的正式化。不大写表示名称尚未正式化。
The Mesoproterozoic–Neoproterozoic stratigraphic record of ancestral North America (Laurentia) comprises three, unconformity-bounded sedimentary successions that are termed, from oldest to youngest, A, B, and C. Recent and ongoing detailed stratigraphic studies of Succession B, along with improved geochronology, allow extension and refinement of existing correlation schemes for northwestern Canada and Alaska. Succession B strata include the Shaler Supergroup of the Amundsen Basin, Mackenzie Mountains supergroup of the Mackenzie Mountains fold belt, Pinguicula group of the Wernecke Mountains inlier, Fifteenmile group of the Ogilvie Mountains inliers, and the lower Tindir Group of Tatonduk inlier. The Katakturuk Dolomite, in the northeast Brooks Range of Alaska, is included with Succession B on the basis of platformal character, geochronology, and inferred paleogeographic affinity. The framework for regional lithostratigraphic correlation of Succession B is built on recognition of four distinctive lithostratigraphic assemblages: two thick stromatolitic platformal carbonate assemblages separated by two largely subaerial siliciclastic assemblages. The correlation is supported by geochronology of detrital zircons from the upper quartzarenite assemblage, which indicates a maximum age of ca. 1000 Ma for the lower part of Succession B. These rocks are interpreted to be remnants of a northwesterly trending (present coordinates) early Neoproterozoic basin-margin promontory (Amundsen-Ogilvie-Mackenzie platform) that developed within an intracratonic basin on the northwest margin of Laurentia. The Neoproterozoic stratigraphic record of northwestern North America bears striking similarity to contemporaneous stratigraphy on other continents, particularly in the Amadeus Basin and Adelaide fold belt of central and southern Australia. Reconstructions of the Neoproterozoic supercontinent juxtapose the eastern margin of ancestral Australia against the western margin of Laurentia during the time these strata were being deposited. The Amundsen-Ogilvie-Mackenzie platform consequently may represent a segment (of the margin) of a large intracratonic basin that rifted apart with the breakup of the supercontinent during the latest Proterozoic. This hypothesis provides a template for future sequence stratigraphic, chemostratigraphic, biostratigraphic, paleomagnetic, and geochronologic comparisons and has implications for predictive economic geology in both areas. Capitalization of group and supergroup indicates formalization according to the International Stratigraphic Code. Noncapitalization indicates that the names have not been formalized.