摘要
对夹持于金沙江缝合带与班公湖-怒江缝合带之间的羌塘地区,用平衡剖面法统计中新生代地层褶皱收缩量,结果表明中生代以来褶皱吸收的南北向的收缩量最小值为29.3%,与由褶皱的翼间角计算出的27.2%的南北向收缩量大体吻合。受来自印度板块与欧亚板块的南北向挤压力的作用,该地区陆陆碰撞以来吸收了429～500km的南北向缩短,总收缩量的百分比为58.8%～62.5%,而陆陆碰撞以来新近纪地层的褶皱收缩量的最大值为31.6%,由此推断断层引起的南北收缩量大约为27.2%～30.9%。对比各构造层的褶皱收缩量,三叠系构造层的褶皱收缩量平均为29.3%,侏罗-白垩系构造层的褶皱收缩量平均为23.2%,古新统-始新统构造层的褶皱收缩量平均为13.8%,渐新统构造层的褶皱收缩量平均为12.3%,新近系构造层褶皱收缩量平均为17.8%。新近系褶皱收缩量的增大反映高原褶皱收缩增强,与该阶段高原垂向强烈隆升协调。羌塘地体中褶皱收缩量的时空分布显示了与高原各阶段的隆升演化相协调的特点。
The Qiangtang Block in Tibetan Plateau which lies between the Bangong-Nujiang and Jinshajiang sutures is a Mesozoic sedimentary basin. Statistic analysis of fold shortening indicates a minimum value of 29.3% since Mesozoic, which is overall consistent with a value of 27.2% calculated by angels between fold wings. Convergence between the Indian and Eurasia plates yielded 429 - 500km north-south shortening in the study area, which was 58.8% -62.5% , while Neogene strata yield a maximum shortening of 31.6% by folding. It is thus suggested that faulting associated shortening is estimated as 27.2% - 30.9%. Fold shortenings in different structure layer are estimated, in which Triassic, Paleocene-Eocene, Jurassic-Cretaceous, Oligecene and Neogene structure layers yield shortening of 29.3% , 13.8% , 23.2% , 12.3% and 17.8% , respectively. It indicates that fold shortening increased postdate Neogene, which is consistent with the strengthened tectonic uplift of Tibetan Plateau in Neogene. The space-time distribution character of folds shrinkage of Qiangtan Block is consistent with the evolvement of uplift belt to some extent.
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2008年第4期401-409,共9页
Geotectonica et Metallogenia
基金
中国地质调查局重大基础研究项目:青藏高原新生代地质作用过程与第四纪环境演变综合研究(项目号:1212010610103)
关键词
青藏高原腹地
羌塘地体
中新生代
褶皱收缩量
隆升
Qinghai-Tibet Plateau hinterland
Qiangtang Block
Mesozoic-Cenozoic
fold shrinkage
uplifting
