摘要
云贵高原乃至中国残积型红土及红土性风化壳的形成年代是一个长期以来悬而未决的问题。本文以云贵高原厚度分别为9.47m和5.4m的两个碳酸盐岩风化剖面为例,探讨了古地磁方法在碳酸盐岩风化剖面定年中的应用。古地磁定年结果初步表明,其发育时间在布容正极性世内,即两个风化壳剖面的发育年龄不会大于0.78MaB.P.。此外,对古地磁方法应用于碳酸盐岩风化剖面定年中可能存在的问题进行了讨论,其中包括风化壳的成因、风化过程中的体积变化、母岩的岩石磁性、磁性载体矿物及其记录磁信号的稳定性等问题。
In China, especially in Yun- Gui Plateau (Plateau in Yunnan province and Guizhou province), the terra rossa exists widely, but their precise forming ages are still unknown. In this paper, two weathered profiles of 9.47m and 5.4m deep are made as example for the study on the application of paleomagnetism dating to terra rossa profiles. The results of paleomagnetism dating suggested that these two terra rossa profiles formed during Brunhes normal polarity chron, i.e. the age of these two profiles should not be earlier than 0.78Ma B.P..In addition, the application of paleomagnetism dating may be affected by some other factors, such as the genesis of terra rossa, the volumetric change within weathering processes, 'contamination' derived by late weathering processes, magnetic minerals of parent rocks, stability of magnetic carriers in terra rossa, etc.. The above issues are also discussed in this paper.
出处
《中国岩溶》
CAS
CSCD
2003年第3期178-190,共13页
Carsologica Sinica
基金
国家重点基础研究发展规划项目("973"
G1998040800)
国家自然科学基金(40001004)
中科院王宽城基金
中国博士后基金(2002032132)资助
关键词
云贵高原
碳酸盐岩
风化壳
古地磁
定年
年代学
磁化率
Yun-Gui Plateau
Carbonate rocks
Terra rossa profile
Chronology
Magnetic susceptibility
Paleomagnetism
Dating
