上扬子区龙马溪组黑色页岩的时空分布和古地理研究

The Lungmachi black shales are widely distributed and well exposed in the Upper Yangtze region of South China. It is one of the major source rocks of petroleum and shale gas in South China. Quantitative study on the temporal and spatial distribution of the Lungmachi black shales and its paleogeographic pattern provide valuable references for the present shale gas exploration. In the present study, we will make a series of field works focusing on the border area around the Sichuan Basin, including section investigation and fossil collection. Based on the graptolite identification, the top and base biozones of the Lungmachi black shales and the graptolite biostratigraphic sequence can be recognized. Based on a unified time scale, we will then collect multidisciplinary data of the sections with the Lungmachi Formation and enter the data into the Geobiodiversity Database (GBDB). All the data will be examined and revised. Meanwhile, geographic information systems (GIS) will be employed to model the temporal and spatial distribution of the Lungmachi black shales in 2- and 3- dimension, and to calculate their distribution area, mean thickness and rock volume. Based on these models, the depositional center of the black shales, rate and direction of thickness changing, and source of terrestrial detritus can also be examined. The results can be used in the exploration and production of the shale gas in South China. In addition, we will also investigate the distributions of both the Lungmachi Formation and the other coeval sediments, and reconstruct the paleogeographic pattern of both lithofacies and biofacies during the studying intervals.

华南上扬子区龙马溪组黑色页岩分布广泛、出露良好，是我国南方早古生代重要的烃源岩地层。对该套页岩开展精细的地层划分与对比、时空分布和古地理格局研究，对我国南方页岩气勘探和开发具有重要的指导意义。本项目立足于上扬子区龙马溪组良好的剖面资源和研究基础，针对重点地区（如覆盖区周缘）进行野外实地剖面测制、样品采集和室内化石鉴定等工作，建立这套地层精细的笔石生物地层划分和对比，识别其顶、底界线的发育情况。在此基础上，依托GBDB数据平台对龙马溪组黑色页岩相关数据进行补充和厘定，利用GIS相关技术和软件对这套黑色页岩的时空分布进行平面和三维建模，制作“笔石带”一级的等时框架下黑色页岩的空间分布图，定量计算其分布面积、平均厚度和沉积总量等特征参数，分析其空间分布型式和变化规律。同时，结合龙马溪组同期异相地层和沉积缺失的分布情况，恢复这一时期的岩相、生物相古地理格局，探讨龙马溪组黑色页岩形成的古地理背景。

华南上扬子区龙马溪组黑色页岩分布广泛、出露良好，是我国南方早古生代重要的烃源岩地层。对该套页岩开展精细的地层划分与对比、时空分布和古地理格局研究，对我国南方页岩气勘探和开发具有重要的指导意义。本项目执行期间，对华南龙马溪组重要剖面和钻井开展了大量的野外实地剖面测制、样品采集和室内化石鉴定、样品分析等工作，依托生物地层和碳同位素地层综合研究，建立了其从露头区至覆盖区精细的地层划分和对比模式。在此基础上，利用GBDB数据库对龙马溪组黑色页岩相关数据进行补充和厘定，利用GIS相关技术和软件对这套黑色页岩的时空分布和古地理格局进行重建和恢复，分析其空间分布型式和变化规律，探讨龙马溪组黑色页岩形成的古地理背景。通过对上扬子区龙马溪组时空分布研究，认识到这套黑色页岩在川黔地区的渐进展布模式和湘鄂地区的圈层分布模式，为页岩气勘探开发的产区优选提供了基础。同时通过下扬子区五峰组和龙马溪组地层和古地理演化发育模式的对比研究，认识到两者不同的古地理成因，前者受控于华南区域局限海滞流环境，后者主要由于全球海平面上升导致。研究共发表标注学术论文4篇，其中SCI论文2篇。