川东地区早中三叠世海水碳氧同位素特征及其成钾意义

Characteristics of Carbon and Oxygen Isotope in Early-Middle Triassic Seawater in Eastern Sichuan Basin and The Significance for Potassium Formation

中文关键词:  古气候  成钾效应  早中三叠世  四川东部

英文关键词:Paleoclimate  Potassiumeffect  Early-MiddleTriassic  EastemSichuan

中文摘要:

      早中三叠世是地球发展史上的一个特殊时期，主要在于其特殊的海陆分布及气候特征，其海水的演化特征一直为人们所关注。文章对四川盆地东部地区的 85个碳酸盐岩碳、氧同位素地球化学特征进行了研究，也对海水原始性进行了分析和判断，同时对海水原始性好的样品进行了碳氧同位素的测试，并运用其结果对古水温进行了估算。研究结果表明，四川盆地东部早中三叠世海相碳酸盐岩沉积期海水温度比较高，飞仙关组期的平均温度为 42.30℃，嘉陵江组期的平均温度为 43.89℃，雷口坡组期的温度为 43.61℃。这与该区测试的石盐流体包裹体的均一温度具有一致性，说明当时早中三叠世的古海水具有较高的温度，高温的气候特征有利于海水的蒸发和浓缩，为钾镁盐的形成提供了气候条件。

英文摘要:

      The Early-middle Triassic is a special period in earth history，mainly due to its special land-sea distribution and climate characteristics，and the evolutionary characteristics of seawater have always been the focus of attention. In this paper，the carbon and oxygen isotope geochemical characteristics of 85 car-bonate rocks in the eastern part of the Sichuan Basin were studied.At the same time，the originality of the seawater was studied and judged，and then the carbon and oxygen isotope tests were carried out on the samples withgoodpreservation of the originality of the seawater，and the paleowater temperature was esti-mated by using the results. The results show that during the early-middle Triassic marine carbonate deposi-tion period in the eastern of Sichuan Basin，the seawater temperature was relatively high，with an average temperature of 42.30 ℃ in the Feixianguan Formation and 43.89 ℃ in the Jialingjiang Formation，and 43.89 ℃in the Leikou Formation.The temperature during the slope formation period was 43.61 ℃.This is consistent with the uniform temperature ofhalite fluidinclusions testedin this area. It shows that the paleo-seawater in the Early and Middle Triassic had a relatively high temperature，and this high-temperature cli-maticfeaturewasconducivetotheevaporationandconcentrationofseawater，whichprovidedclimaticcon-ditionsfortheformationofpotassium-magnesiumsalts.