论文部分内容阅读
本文对西沙群岛西科1井钻孔岩心晚中新世-上新世生物礁沉积进行了详细的岩石磁学、磁性扫描与磁性地层学研究.结果显示,西科1井生物礁相沉积中的载磁矿物主要是磁铁矿.我们推测,这些磁铁矿的微小颗粒主要来自海水中含有的陆源物质,在生物生长过程中通过珊瑚体或其它寄生生物对海水的过滤与吸附作用保存在生物礁沉积中.进一步的磁性地层学研究及其与地磁极性年表的对比发现,在上新统莺歌海组、上中新统黄流组内部可获得多个年龄控制点,并对莺歌海组和黄流组的底界位置给出了初步制约.其中,莺歌海组记录了C2An.3n和C3n.4n,黄流组记录了C3An.2n至C5n.2n.虽然这一对比方案存在一定不确定性,但是在现阶段生物地层年代及其它年代学资料相对匮乏的情况下,我们认为本项研究的磁性地层学结果能为西沙群岛晚中新世以来的生物礁沉积提供更多可靠的年龄控制点,并为今后的区域地层对比提供磁性地层年代学依据.
In this paper, detailed rock magnetism, magnetic scanning and magnetic stratigraphic studies were carried out on the late Miocene-Pliocene reef sediments in the borehole core of Well Xike-1 in the Xisha Islands. The results show that in the reef facies sediments Of the magnetite-bearing minerals are mainly magnetite.We speculate that the tiny particles of these magnetites mainly come from the terrestrial substances contained in the seawater, which are preserved in the biological growth process through filtration and adsorption of seawater by corals or other parasites Reef deposition.In the further study of magnetic stratigraphy and its comparison with the geomagnetic polar chronology, we found that there are many age control points available in the upper Songliao Epoch, the Upper Miocene Huangliu Formation, The bottom boundary positions of Yinggehai and Huangliu groups give initial constraints, in which C2An.3n and C3n.4n were recorded in Yinggehai Formation and C3An.2n to C5n.2n were recorded in Huangliu Formation. Although this However, at this stage of biological stratigraphy and other chronological data is relatively scarce, we believe that the magnetic stratigraphic results of this study can provide for the reef deposition of the Xisha Islands since the late Miocene More reliable Age control point, and provide reference for magnetic stratigraphy for future stratigraphic correlation.