福建宁德地区第四纪年代地层时空特征及对海面变化的指示

This paper is the result of geological survey engineering. [Objective] Clarifying the Late Quaternary stratigraphic framework in Ningde area, Fujian can provide basic information to support the regional division of saline and freshwater, and new comparable information for the study of Late Quaternary marine intrusion in Eastern China. [Methods] Through lithological, chronological and micro−body paleontological analyses of hole NDGK2 and regional borehole comparisons, we reconstructed its Late Quaternary stratigraphic framework and further explored the regional stratigraphic spreading characteristics and evolutionary processes. [Results] The Quaternary stratigraphy of hole NDGK2 has been deposited since the Late Pleistocene, and there are three layers of dark gray clay from bottom to top, with ages of about 90 ka, 39-44 ka, and <10 ka, respectively. [Conclusions] The Quaternary stratigraphy of hole NDGK2 is developed on top of ancient weathering crust, and is mainly deposited since the late Middle Pleistocene−early Late Pleistocene. There are three layers of dark gray clay in the core of the borehole, all of which are likely to be deposited during the transgression period, and the three layers of dark gray clay may correspond to MIS5, MIS3 and MIS1 phases, respectively. The spatial difference of the development of dark gray clay layer shows that the transgression scope of MIS3 is wider than that of MIS5. At that time, the paleotopography was close to the modern topography, and the tectonic subsidence was obvious. After MIS3, the structure was relatively stable, and the most extensive transgression was formed with the influence of the maximum transgression surface in the Holocene.