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Criteria for the recognition of clastic halite: The modern Dead Sea shoreline
Sedimentology ( IF 2.6 ) Pub Date : 2021-06-11 , DOI: 10.1111/sed.12907
Tim K. Lowenstein 1 , Mebrahtu F. Weldeghebriel 1 , Ido Sirota 2, 3 , Haggai Eyal 2, 3 , Ziv Mor 2, 3 , Nadav G. Lensky 3
Affiliation  

Sedimentological studies of modern halites have focused on shallow water to subaerially-exposed saline pans, where in-place crystal growth, dissolution and cementation textures dominate. Clastic halite transported and deposited by waves and unidirectional currents as bedload is poorly known. This paper: (i) describes and interprets the diagnostic sedimentary features of clastic halite from a modern outcrop exposed along the north-western coastline of the Dead Sea; and (ii) provides criteria for recognition of clastic halite in the rock record. The 2 m thick halite unit at Nahal Og was deposited within the last four decades at water depths <30 m as Dead Sea levels fell ca 30 m. Clastic halites consist of frameworks of sorted crystals with point contacts and no preferred growth fabrics. Halite cumulates, deposited as suspended load, precipitated in the water column and sank to the brine bottom. The excellent sorting and purity of halite crystal layers are unique to cumulates. Small-scale ripple cross-stratified thin beds and intraclast conglomerates were deposited from bedload. Halite bedload deposits (composed of halite flat pebbles, ooids, rafts, single clear crystals, cumulate crystals, mud intraclasts and rounded mudballs, foraminifera, gypsum) reflect wave transport and deposition via oscillatory flow above wave base, or by unidirectional flow in the breaker and surf zones. In addition, waves on the Dead Sea coast generate longshore currents. Thin beds produced by wave-influenced oscillatory transport of halite are symmetrical in cross-section. Less common cross-stratified units with asymmetrical cross-sections indicate unidirectional currents. Clastic halite, especially as a bedload deposit, has rarely been identified in ancient evaporites. Shoreline deposits from ancient halites, however, must contain wave-reworked and current-reworked layers and should be common in saline giants, given their enormous size and potential for generating waves and currents. Documentation of modern clastic halite may lead to a better understanding of ancient hypersaline environments on Earth.

中文翻译:

碎屑岩盐的识别标准:现代死海海岸线

现代岩盐的沉积学研究集中在浅水到地下暴露的盐田,在那里晶体生长、溶解和胶结结构占主导地位。由波浪和单向流作为床负载运输和沉积的碎屑岩盐鲜为人知。本文:(i) 描述和解释了沿死海西北海岸线暴露的现代露头碎屑岩盐的诊断沉积特征;(ii) 提供在岩石记录中识别碎屑岩盐的标准。Nahal Og 的 2 m 厚的岩盐单元在过去的 40 年里沉积在水深 <30 m 处,因为死海平面下降了30 米。碎屑岩盐由分选晶体的框架组成,具有点接触并且没有优选的生长结构。岩盐堆积,作为悬浮物沉积,在水柱中沉淀并沉入盐水底部。岩盐晶体层的出色分类和纯度是累积物所独有的。小规模波纹交错层状薄层和碎屑内砾岩由床荷载沉积而成。岩盐床载沉积物(由岩盐扁平卵石、鲕粒、筏、单晶、堆积晶体、泥内碎屑和圆形泥球、有孔虫、石膏组成)通过波基上方的振荡流或破碎器中的单向流反射波传输和沉积和冲浪区。此外,死海沿岸的波浪会产生沿岸洋流。岩盐受波浪影响的振荡输运产生的薄层横截面是对称的。具有不对称横截面的不太常见的交叉分层单元表示单向电流。在古代蒸发岩中很少发现碎屑岩盐,特别是作为床层沉积物。然而,来自古代岩盐的海岸线沉积物必须包含波浪再加工和电流再加工的层,并且应该在盐巨星中很常见,因为它们巨大的尺寸和产生波浪和洋流的潜力。对现代碎屑岩盐的记录可能有助于更好地了解地球上古老的高盐度环境。在古代蒸发岩中很少发现。然而,来自古代岩盐的海岸线沉积物必须包含波浪再加工和电流再加工的层,并且应该在盐巨星中很常见,因为它们巨大的尺寸和产生波浪和洋流的潜力。对现代碎屑岩盐的记录可能有助于更好地了解地球上古老的高盐度环境。在古代蒸发岩中很少发现。然而,来自古代岩盐的海岸线沉积物必须包含波浪再加工和电流再加工的层,并且应该在盐巨星中很常见,因为它们巨大的尺寸和产生波浪和洋流的潜力。对现代碎屑岩盐的记录可能有助于更好地了解地球上古老的高盐度环境。
更新日期:2021-06-11
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