Magnetostratigraphy of Biogenic Reef in the Sanya Formation of Borehole XK-1 From Xisha Islands and Its Environmental Significance
YI Liang
WANG Zhen-feng
ZHANG Dao-jun
LIU Xin-yu
YOU Li
LUO Wei
ZHU You-hua
QIN Hua-feng
DENG Cheng-long
Abstract：Biogenic reef is one of the important sediment types not only in the South Chi-na Sea (SCS),but also in the Western Pacific Ocean,and plays an important role in modulating global climate and carbon cycle through biological processes.In this paper, a detailed study of paleomagnetic chronostratigraphy is carried out for a Neogene biogen-ic reef sequence of the Sanya Formation in Borehole XK-1 drilled recently in the Xisha Islands in the northern SCS.The main results are as follows:(1 )The Early-Miocene Sanya Formation recorded C5Dn-C6An normal chrons.(2)Based on the age constraints of the whole borehole,the Neogene biogenic reefs in the Xisha region have three stages:two regular stages prior to about 1 6.5 Ma and after about 13.5 Ma,respectively and one rapid developing stage from 1 6.5 Ma to 13.5 Ma.The latter one is named'Mid-Miocene Shift Event'herein.By comparing the new findings with the results obtained previously, it is speculated that the origin of the biogenic reefs in the Xisha region would be notably earlier than ~20 Ma which was considered in the past,and that the three-stage evolu-tionary model for the biogenic reefs was possibly related to the tectonic environment during the termination of seafloor spreading of the SCS.
Keywords：magnetostratigraphy230 Th datingbiogenic reefsSouth China Seaneo-gene
Publication Date：2016-01-01
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：11( 1-11 )