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首页> 外文期刊>Journal of geodynamics >Precambrian-Cambrian boundary interval deposition and the marginal platform of the Avalon microcontinent
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Precambrian-Cambrian boundary interval deposition and the marginal platform of the Avalon microcontinent

机译：前寒武纪-寒武纪边界层沉积和阿瓦隆微大陆的边缘平台

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Thick terminal Proterozoic-lowest Cambrian successions allow reference of the Saint John, New Brunswick, and MacCodrum Brook, southern Cape Breton Island, areas to the marginal platform of the Avalon microcontinent. Marginal-platform siliciclastic-dominated sequences form a cover on Late Precambrian arc successions from southern New Brunswick to North Wales. Their deposition in fault-bounded basins began with the origin of the Avalon microcontinent and development of a persistent transtensional regime in the latest Precambrian. The terminal Proterozoic-lowest Cambrian on the Avalonian marginal platform consists of three successive lithofacies associations: lower subaerial rift to marginal-marine facies; overlying cool-water, wave-influenced, marine platform sandstones and shales; and higher macrotidal quartz arenites ( = Avalonian depositional sequences 1-2). Only the Lower Cambrian macrotidal quartz arenites onlap southeast, where they form the oldest Cambrian unit on the inner platform. These major lithofacies are the Rencontre, Chapel Island, and Random formations, respectively, in Avalonian North America. Southwest thinning of the Rencontre-Chapel Island-Random interval in southern New Brunswick reflects slower subsidence of a fault-bounded area in the city of Saint John. The depositional sequence 1-2 unconformity, which falls in the sub-trilobitic Lower Cambrian Watsonella crosbyi Zone of the Chapel Island Formation, persists for 650 km along the marginal platform from southeastern Newfoundland to southern New Brunswick and, potentially, appears in Cape Breton Island. Latest Precambrian-earliest Cambrian epeirogenic and depositional history was very uniform along the marginal platform, and a unified lithostratigraphic nomenclature is appropriate.
机译：厚末元古生代最低的寒武纪演替允许参照圣约翰，新不伦瑞克和布雷顿角岛南部的麦克德鲁姆布鲁克到阿瓦隆微大陆边缘平台的区域。从新不伦瑞克南部到北威尔士的前寒武纪晚期弧演替作用的边缘地层为硅质碎屑为主的边缘地层。它们在断层限定盆地中的沉积始于阿瓦隆微大陆的起源，以及在最新的前寒武纪中持续的张性张性发展。阿瓦隆边际台地上的末代元古代最低寒武纪由三个相继的岩相组合组成：低层陆缘裂谷到边缘海相；上覆冷水，波浪影响的海洋平台砂岩和页岩；和较大的潮汐石英芳构岩（=阿瓦隆沉积序列1-2）。东南部只有下寒武统大潮汐石英岩，在内部平台上形成了最古老的寒武纪单元。这些主要岩相分别是北美阿瓦隆地区的Rencontre，Chapel Island和Random地层。新不伦瑞克省南部的Rencontre-Chapel Island-Random区间的西南变薄反映了圣约翰市断层边界区域的沉降速度较慢。沉积序列1-2不整合面位于Chapel Island组的次三叠纪下寒武统Watsonella crosbyi区，沿从纽芬兰东南部到新不伦瑞克南部的边缘平台持续650 km，并可能出现在布雷顿角岛。最新的前寒武纪最早的寒武纪成因和沉积史沿边缘平台非常均匀，因此采用统一的岩石地层学术语是合适的。

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