中更新世撞击事件年龄的高分辨率估算  

HIGH-RESOLUTION AGE ESTIMATION OF THE MID-PLEISTOCENE IMPACT EVENT

作　　者：李霞[1] 赵泉鸿[1] 黄宝琦[2] 苏新[3] 

机构地区：[1]同济大学教育部海洋地质重点实验室,上海200092 [2]北京大学环境科学学院,北京100871 [3]中国地质大学,北京100083

出　　处：《海洋地质与第四纪地质》2004年第2期73-77,共5页Marine Geology & Quaternary Geology

基　　金：高等学校博士学科点专项科研基金资助课题(20010247020);国家自然科学基金重点项目(40331002);国家重点基础研究发展规划项目(2000078502)

摘　　要：ODP1146B孔位于南海北部陆坡,从孔深115 58～116 09mcd之间厚51cm层段中采取沉积物样品46个,进行了微玻陨石分析。应用古地磁、氧同位素和生物等地层年代资料,计算了位于孔深115 90mcd处微玻陨石层的年龄,其中依据磁性地层学事件的年代控制点计算得出的撞击年龄为792 6ka,微玻陨石年龄早于B/M界线12 6ka,晚于氧同位素20 2期约7ka,早于19 1期约5ka,表明中更新世撞击事件与全球冰期和间冰期发生及B/M界线磁场倒转并无明显的因果关系。Total 46 sediment samples were collected for microtektite analysis from a 51 cm-thick section between 115.58 and 116.09 mcd at ODP Hole 1146B (19°27′N, 117°16′E, water depth 2 091 m, core length 245 m), northern slope of the South China Sea. Age data of paleomagnetic, oxygen isotopic and biostatigraphic events have been implied to estimate the age of the microtektite layer which is located at 115.90 mcd, individually. Of them the dating of the impact event at 792.6 ka BP is more precise by using magnetostratigraphical events as age controlling points in the age estimation. Our research also indicates that the microtektite deposition was 12.6 ka prior to the magnetic reversal at the B/M boundary and ～ 7 ka to the MIS 19.1, but ～5 ka later than the MIS 20.2, indicating no causal relationship between the mid-Pleistocene impact event and the formation of the global glaciation and interglaciation, and the magnetic reversal at the B/M boundary.

关 键 词：磁性地层学事件 撞击事件 微玻陨石 古地磁 同位素 中更新世 南海 

分 类 号：P539.3[天文地球—古生物学与地层学] P736.223[天文地球—地质学]