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
Material Differentiation and Its Response to the “PETM” Events in Continental Fault Lake during the Early Paleogene Period: A Case Study of Kongdian Formation in Jiyang Depression

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12CO2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12C吸收沉淀,造成湖泊沉积记录中的δ13C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.
Paleocene Eocene climate (PETM) events in Early Paleogene period on the Earth had serious impact on the global carbon cycle process and the terrestrial and marine ecological environment system. In this paper, on the basis of general thin sections, elemental analysis ,carbon isotope, TOC et al., the impact of Paleocene Eocene lake environment of Jiyang rifted basin, Bohai bay on the temporal and spatial variation and response of “PETM” is studied, and it is found Jiyang basin experienced early multicycle evolution processes，detrital material and chemical differentiation occurred at the same time in lacustrine basin, and terrestrial weathering and chemical sedimentary differentiation indicates the change of extreme climate. In this period, the lake water experienced gradual salinization characterized by the spatial zoning and time-evolution stage，which is a direct response to the occurrence of hot climate events. Time-space evolution of the lake was subject to “PETM” events. The lake was not fully salty in the early events with prosperous plankton. Early phytoplankton absorption of 12CO2 led to the higher productivity in the ancient Lake, which dropped to a minimum with the lake turning increasingly salty and more difficult for the survival. δ13C of lacustrine sedimentary records are in obvious negative bias due to excessive 12C absorption and precipitation, resulting in, a maximum of 5‰. It is confirmed that global “PETM” events affected the time-space evolution and differentiation process of material in Jiyang depression during Paleocene-Eocene