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江陵凹陷古新统沙市组和始新统新沟嘴组下段沉积为一套巨厚含盐岩系。对始新世早期新沟嘴组下段沉积的无水芒硝中的原生单一液相流体包裹体采用冷冻法进行均一温度测定。原生流体包裹体是在矿物沉积的过程中被捕获的,矿物生长过程中所圈闭的流体(即古盐湖卤水)保存了当时地质环境的各种地质地球信息,可以为研究古温度、古水体成分、古大气成分以及生物的演化等方面提供可靠的定量数据。测温结果显示,其均一温度范围是17.6~38.5℃,均值为27.2℃。这可能说明,江陵凹陷早始新世新沟嘴组下段的古气温在27.2℃左右,极端情况下,当时的古气温可达38.5℃。通过与前人的研究比对发现江陵凹陷自沙市组上段到新沟嘴组下段有明显降温趋势。由于古新世—始新世的升温事件(PETM)使全球气温普遍升高,可以看出江陵凹陷自新沟嘴底部虽已进入PETM事件后的降温期但气候依然以炎热干旱为主要特征。
The Lower Pleistocene of the Paleocene Shashi Formation and the Eocene Xingouzui Formation of Jiangling Sag deposited as a set of huge thick salt rock series. The homogeneous single-phase fluid inclusions in anhydrous mirabilite deposited in the lower part of the Eocene Early Xingouzui Formation were measured by freezing method. The primary fluid inclusions are trapped during the deposition of minerals. The fluid trapped in the minerals during the growth of the minerals (ie, the ancient salt lake brine) has preserved various geo-earth information of the geological environment at that time and can be used for studying the ancient temperature, Composition, paleo-atmospheric composition and biological evolution to provide reliable quantitative data. Temperature measurement results show that the average temperature range is 17.6 ~ 38.5 ℃, with an average value of 27.2 ℃. This may indicate that the palaeoclimatic temperature of the lower Paleocene Xincocelitz Formation in Jiangling depression is about 27.2 ℃, and in the extreme case, the paleo-climate temperature at that time was 38.5 ℃. Through the comparison with previous studies, it is found that the upper part of the Shashi Formation in Jiangling Depression reaches a downward trend in the lower part of the Xingouigou Formation. Due to the global warming of the Paleocene-Eocene warming event (PETM), it is obvious that the climate is still dominated by the hot and dry climate, although the bottom of the Zengxigou mouth in Jiangling sag has entered the cooling period after the PETM event.