早古近纪陆相断陷型湖泊物质分异作用及其对“PETM”事件的响应:以济阳坳陷孔店组为例

发布时间：2018-01-20 08:21

本文关键词： “PETM”事件环境波动陆相断陷湖泊古近纪早期济阳坳陷石油地质.　出处：《地球科学》2016年11期 　论文类型：期刊论文

【摘要】：古近纪早期,地球上发生了古新世-始新世极热气候(PETM)事件,严重影响全球碳循环过程和海陆生态环境系统.依据普通薄片、元素分析、碳同位素、TOC等实验结果.研究了渤海湾盆地济阳断陷湖盆古新世-始新世时期的湖泊环境时空波动变化及其对PETM事件的响应,发现济阳断陷湖盆早期经历了多旋回的演化过程,湖盆中碎屑物质和化学物质的分异作用同时发生,陆地风化作用和化学沉积物质分异指示了极热气候的变化过程;该时期湖水为逐渐咸化的盐湖环境,具有空间的分带性和时间的阶段演化性,湖水咸化是热气候事件发生的直接响应;湖泊的时空波动演化经历了古新世-始新世时期的极热气候(PETM)事件,该事件早期湖泊尚未完全咸化,浮游生物比较繁盛,早期浮游植物对12 CO2的吸收,会导致短暂的湖泊古生产力较高,但是随着湖盆逐渐咸化,生物的活动存活较难,主要以旱生植物为主,古生产力降到最低.由于过量的12 C吸收沉淀,造成湖泊沉积记录中的δ13 C明显负偏,最大可达5×10-3.由此证实全球PETM事件影响了古新世-始新世之交济阳断陷湖盆的时空演化和物质分异过程.
[Abstract]:In the early Paleogene, PETM events occurred on the earth, which seriously affected the global carbon cycle process and marine and terrestrial ecological environment systems. The temporal and spatial fluctuation of lake environment during Paleocene to Eocene in Jiyang fault depression of Bohai Bay basin and its response to PETM events were studied. It is found that the early stage of Jiyang faulted lacustrine basin experienced a multi-cycle evolution process, and the differentiation of clastic material and chemical substance occurred simultaneously in the lake basin. Land weathering and chemical sediment differentiation indicate the process of extreme thermal climate change. In this period, the lake water is a salt lake environment, with spatial zonation and temporal evolution. The salinization of lake water is the direct response of the thermal climate event. The temporal and spatial fluctuation of lakes experienced the PETM event in Paleocene and Eocene. The lake was not completely salinized and plankton was abundant in the early stage of the event. The absorption of 12 CO2 by early phytoplankton led to higher paleoproductivity of the lake, but with the lake basin gradually brackish, the activity of organisms was difficult to survive, mainly xerophytes. The paleoproductivity is reduced to the lowest. The 未 13 C in the lake sediment record is obviously negative because of the excessive absorption and precipitation of 12C. The maximum is 5 脳 10 ~ (-3). It is confirmed that the global PETM event affected the spatiotemporal evolution and material differentiation of the Jiyang fault basin in Paleocene and Eocene.
【作者单位】：复杂油气田勘探开发重庆市重点实验室;中国地质大学生物地质与环境地质国家重点实验室;重庆科技学院石油与天然气工程学院;中国石化胜利油田分公司地质科学研究院;
【基金】：国家自然科学基金项目(No.41202043) 生物地质与环境地质国家重点实验室开放基金项目(No.GBL21506) 中国石油科技创新基金项目(No.2014D-5006-0108) 重庆市教委科学技术研究项目(No.KJ1401316)
【分类号】：P534.61;P532
【正文快照】： 全球晚古新世-早始新世记录着一系列短暂的热事件,其中,发生在古新世-始新世之交的“PETM”事件为该时期的极热气候事件(Zachos,2001;Cramer et al.,2009;Morón et al.,2013).尽管温度重建存在一定程度的不确定性,但古近纪早期全球温暖气候具有一致认识(Arkaah et al.,2006).

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