Characterization of sulfate mineral deposits in central Thailand
Characterization of sulfate mineral deposits in central Thailand
复制标题
DOI：
10.1111/iar.12175
复制
发表时间：
2017-03
期刊：
影响因子：
1.5
通讯作者：
J. Kuroda;H. Hara;K. Ueno;Thasinee Charoentitirat;T. Maruoka;T. Miyazaki;Akira Miyahigashi;S. Lugli
中科院分区：
文献类型：
--
作者：
J. Kuroda;H. Hara;K. Ueno;Thasinee Charoentitirat;T. Maruoka;T. Miyazaki;Akira Miyahigashi;S. Lugli
本文介绍了泰国中部那空沙旺东北部硫酸盐矿床的岩相学和地球化学数据，并对其年龄提出了新的限制。矿床上部主要由强烈变形的块状、结节状石膏组成，下部为变形较小的层状硬石膏。它们被含有中三叠世锆石（约240 Ma）的安山岩脉侵入。这些脉岩可能是早中三叠世素可泰弧区域岩浆活动的一部分。硫同位素（δ 34 S）和锶同位素（87 Sr/86 Sr）分别为15.86 ‰ ~ 16.26 ‰和0.70810 ~ 0.70817。与中生代海水同位素演化曲线的比较表明，这些值是最好的解释，从石炭纪海水，特别是密西西比时代（约326马）的海水中的硫酸盐沉淀，这将是一致的石灰岩中的钙质化石，作物在这个网站周围以前的研究。我们的解释是，钙长石石膏最初沉淀从超咸水浅泻湖或货架上Khao Khwang平台在Serpukhovian期间，这种石膏变成硬石膏在早期埋藏。在中三叠世，硬石膏被安山岩脉切割，最近，其上部在折返过程中再水化，在地表附近形成次生石膏。
In this paper we present petrographic and geochemical data of sulfate mineral deposits in northeast Nakhon Sawan, central Thailand, and provide new constraints on their age. The deposits are made up mainly of strongly deformed nodular and massive gypsum in the upper part, and less deformed layered anhydrite in the lower part. They are intruded by andesitic dikes that contain Middle Triassic zircons (ca 240 Ma). These dikes are probably part of the regional magmatic activity of the Sukhothai Arc during the Early to Middle Triassic. Sulfur (δ34S) and strontium (87Sr/86Sr) isotopic compositions of the sulfates range from 15.86 ‰ to 16.26 ‰ and from 0.70810 to 0.70817, respectively. Comparisons with the Phanerozoic seawater isotopic evolution curve indicate that those values are best explained by precipitation of the sulfates from Carboniferous seawater, in particular seawater of late Mississippian age (ca 326 Ma), and this would be consistent with previous studies of calcareous fossils in the limestones that crop out around this site. Our interpretation is that evaporitic gypsum was originally precipitated from hypersaline seawater on a shallow lagoon or shelf on the Khao Khwang Platform during the Serpukhovian, and that this gypsum changed to anhydrite during early burial. The anhydrite was then cut by andesitic dikes during the Middle Triassic, and more recently the upper part of which was rehydrated during exhumation to form secondary gypsum near the surface.