利用GBDB数据库与GIS技术绘制高精度古地理图

Making high-resolution palaeogeographic maps based on GBDB database and GIS technique

进入21世纪,随着互联网、数据库和地理信息系统(GIS)技术的快速发展,古地理学研究及古地理图的绘制也面临新的机遇与挑战,逐渐从定性走向定量,从基于单因素、单学科信息到基于多因素、多学科综合信息。新一代基于数据库和GIS技术的高精度古地理图的绘制,与传统的定性或手工绘制的古地理图相比,涵盖的学科信息广、涉及的数据量大、图件精度高、可叠加各种定量分析的结果,是未来古地理图绘制的主流方向,并将成为定量古地理研究的重要辅助手段。GBDB数据库庞大的地层学和古生物学数据资源,以及以剖面为核心的数据结构,使其成为目前最适合开展定量古地理研究和古地理图绘制的开放数据平台。作者收集、整理了华南435个剖面的综合地层数据,通过数据的标准化和专家厘定,绘制得到了华南奥陶纪凯迪晚期的高精度古地理图。研究表明,凯迪晚期,扬子地台上广泛发育五峰组黑色页岩沉积;扬子地台的西北缘、西南缘、湖南中南部、下扬子地区等沉积了其他岩相地层;华南南部大范围地区、四川中部等均已抬升暴露,缺失本期地层。总体来看,该时期华南呈现了三面古陆环绕的浅水台地这一古地理格局。

In the twenty-first century, with the rapid development of the internet, database and GIS techniques, the palaeogeographical research and the making of palaeogeographic maps also face new op- portunities and challenges, gradually transferring from qualitative to quantitative, from single factor or sin- gle discipline to integrated. Comparing with traditional qualitative and manual palaeogeographic maps, the new-generation maps, which represent the major direction of palaeogeographic mapping, cover broader range of subjects, involve much larger dataset, provide more precisions, and support the integration of results of quantitative research. The huge data resources of stratigraphy and palaeontology in the Geobiodi- versity Database （GBDB） , as well as the section-based data structure, make the GBDB most suitable as an open platform for carrying out palaeogeographic research and mapping. We collect a comprehensive dataset of hundreds of sections from South China through the GBDB platform. All the data were standardized and verified by stratigraphic and palaeontolotical experts. The verified dataset was then used to create the late Katian （Late Ordovician） palaeogeographie map of South China with GIS technique. The map shows that, during the late Katian of the Late Ordovician, the Yangtze Platform was mostly deposited by the black shales of the Wufeng Formation, while the other areas, such as the northwestern or southwestern margins of the Yangtze Platform, southern and central Hunan Province, and the southeastern Lower Yangtze Platform received sediments of other lithofacies. Most areas in the south part of South China and the central Sichuan Province were uplifted above the sea level and lacked of sediments of this period. Overall, South China showed a distinct palaeogeographic pattern of a platform surrounded on three sides by oldlands during the late Katian.