摘要
本文展示了柴达木盆地西北地区大浪滩盆地梁ZK05钻孔上部330m岩芯的最新磁性地层结果。梁ZK05钻孔的磁极性序列记录了4个正极性亚时,分别对应于布容期、Jaramillo、Cobb Mountain和Olduvai。磁极性序列底部未出现Reunion亚时,其年代应小于2128ka,B/M界限深度位于94m。根据钻孔的平均沉积速率,我们推算出钻孔最顶部的年代为111ka,钻孔在330m深度的年代为2046ka。由此可知,钻孔330m以下的卵砾石层沉积的结束年代为2Ma,代表阿尔金山的这次强烈隆升应早于2Ma,与青藏运动B幕相当,其启始时间为2.6Ma,结束时间大致为2Ma。另外,梁ZK05钻孔记录了3次极性漂移事件,位于51~58m、207.5~212m和249~252m,分别对应于Calabrian Ridge2（515~525ka）、Gardar（1465~1485ka）和Gilsa（1567~1575ka）。我们在沈振枢等人（1993）的8个钻孔磁性柱基础上,加上梁ZK05钻孔和ZK02钻孔的磁极性序列,辅以最新的国际标准磁极性年表,建立了柴达木盆地最新的磁性地层年代框架。
This study displays the new magnetostratigraphic results of a 330-m-thick sequence from Liang ZK05 borehole in Dalangtan,northwest Qaidam Basin.Four normal chron zones are recognized from magnetic polarity sequence of Liang ZK05 borehole,which are regarded as Brunhes,Jaramillo,Cobb Mountain,and Olduvai by comparing with the Geomagnetic Polarity Time Scale.For no Reunion subchron existing in the bottom of magnetic polarity sequence,the age of the 330-m-thick sequence is less than 2128 ka.The B/M boundary is located in 94 m.According to the average sedimentary rate based on magnetostratigraphic results,the age of top part of borehole is calculated to 111 ka and the bottom of borehole dates 2046 ka.Therefore,the molasse deposits of Liang ZK05 borehole terminated in 2 Ma,which indicates that the age of the uplift of Altyn Tagh Mountains was before 2 Ma.This uplift stage of Altyn Tagh Mountains is regarded as Qinghai-Tibet Movement Phase B,beginning at 2.6 Ma and terminating approximately at 2 Ma.Three magnetic excursion events have been extracted from the magnetic polarity sequence in the depth of 51～58 m,207.5～212 m,and 249～252 m,which should be corresponding to Calabrian Ridge 2（515～525 ka）,Gardar（1465～1485 ka）,and Gilsa（1567～1575 ka）,respectively.On the basis of eight magnetic polarity sequences from Shen Zhenshu et al.（1993）,plus two magnetic polarity sequences of Liang ZK05 and ZK02,we have established the new magnetostratigraphic age frame of Qaidam Basin by comparing with the latest Geomagnetic Polarity Time Scale.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2010年第11期1631-1640,共10页
Acta Geologica Sinica
基金
中国地质调查局项目(编号1212010818057
1212010818058
1212011018004)资助的成果
关键词
柴达木盆地
大浪滩
梁ZK05
磁性地层
阿尔金山隆升
年代框架
Qaidam Basin
Dalangtan
Liang ZK05
magnetostratigraphy
the uplift of Altyn Tagh Mountains
age frame
