Pleistocene sea-level yo-yo recorded in stacked beaches, Bermuda south shore
Pleistocene sea-level yo-yo recorded in stacked beaches, Bermuda south shore
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百慕大南岸堆积海滩记录的更新世海平面溜溜球
DOI：
10.1130/0-8137-2300-0.295
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发表时间：
1995
期刊：
影响因子：
64.8
通讯作者：
D. Wehmeyer
中科院分区：
文献类型：
--
作者：
D. Meischner;Ruediger Vollbrecht;D. Wehmeyer
在构造稳定的百慕大碳酸盐台地（大西洋，西经 64°50'；北纬 32°20'）上，更新世期间的海平面波动留下了一堆夹有红色土壤（冰川）的海洋和风成石灰岩（间冰期）。每个海洋高位都沉积了新的、基本相似的沉积物序列。沿着百慕大南岸，出现了多达三个更新世海滩序列，一个叠一个。在这项研究中，我们描述了重叠/重叠海滩沉积物的主要序列，并将葡萄湾的实际部分分配给与同位素阶段 5e（落基湾）以及同位素阶段 5e（洛基湾）以及暂定 7ac 和 7e（上贝尔蒙特和下贝尔蒙特）相关的各个高位。研究了成岩作用印记，以将海洋和大气胶结阶段与海侵、高位和地面暴露时间联系起来。即使在较古老的海滩（贝尔蒙特），原生高镁方解石和文石颗粒也很少受到成岩蚀变的影响。胶结物以颗粒周围重复出现的高镁方解石外皮形式出现，通过磨损和微弱的陨石蚀变而分开。年轻的海滩（洛基湾）在流星雨的环境中凝固了。没有发现证据表明贝尔蒙特时间延长的淡水透镜体和贝尔蒙特的流星蚀变是由兰德（1970）假设的，以解释硬化贝尔蒙特海滩沉积物惊人的长凳状外观。
On the tectonically stable Bermuda Carbonate Platform (Atlantic Ocean, 64 50’W; 32 20’N), sea-level fluctuations during the Pleistocene left a pile of marine and eolian limestones (interglacial) intercalated with red soils (glacial). Each marine highstand deposited a new, basically similar sequence of sediments. Along Bermuda South Shore, as many as three Pleistocene beach sequences occur, stacked one above another. In this study, we describe the principal sequence of onlapping/offlapping beach deposits, and assign actual sections in Grape Bay to individual highstands that correlate to isotopic stages 5e (Rocky Bay), and tentatively, 7ac and 7e (Upper and Lower Belmont).The diagenetic imprint is studied to link phases of marine and meteoric cementation with times of transgression, highstand, and subaerial exposure. Even in the older beaches (Belmont), primary high-Mg calcite and aragonite grains are little affected by diagenetic alteration. Cements occur as repeated high-Mg calcite rinds around grains, separated by abrasion and weak meteoric alteration. The younger beach (Rocky Bay) was cemented in the meteoric environment. No evidence was found for an extended Belmont-time fresh-water lens and meteoric alteration in the Belmont postulated by Land (1970) to explain the striking bench-like appearance of the indurated Belmont beach deposits.