残留被动大陆边缘盆地——一种被忽略的盆地类型

各种盆地分类中人们忽略了一种盆地类型,即"残留被动大陆边缘盆地"。这种盆地发育在大洋中脊,随着板块会聚已经俯冲到活动大陆边缘之下,大洋收缩到十分狭窄的程度但仍然保持被动大陆边缘的基本性质,且由于俯冲板块的板块拉力和挠曲造成的表层张力张性正断层活动较强烈。由于这种盆地是板块尚未碰撞时发育的,因此与前陆盆地还没有必然联系,随着板块碰撞和前陆盆地的形成,它可以演化成残留洋盆地前陆盆地。广西"钦防海槽"和"十万大山"盆地区,由于早古生代的华夏古陆并不是一个统一的古陆块,因此在中奥陶世-志留纪武夷、闽台微陆块向华南古板块拼贴时,"钦防海槽"即处于"残留被动大陆边缘盆地"演化阶段,其后经历了早泥盆世残留洋盆地、晚古生代特提斯被动大陆边缘盆地、晚二叠世早期前陆盆地、中生代前陆盆地和新生代走滑断陷盆地的盆地性质转化过程。

Residual basin of passive continental margin-a neglected basin type

One type of basin known as "residual basin of passive continental margin" has been overlooked in all basin classifications.It is usually formed in mid-oceanic ridge and was subducted under active continental margin with plate convergence.However,its basic features of passive continental margin remain unchanged except that normal faulting is rather intensive due to surface tension caused by flexing of the subducted plates.The "Qinfang trough" and "Shiwandashan basin" in Guangxi province was not a unified ancient continent block with the Cathaysia in Eopaleozoic.Therefore,when Wuyi and Mintai mini-blocks attached to South China ancient plate,the "Qinfang trough" was in the evolution stage of the "residual basin of passive continental margin".Later,it evolved successively into a remnant ocean basin in Early Devonian,a Tethyan passive continental margin basin in Neopaleozoic,a foreland basin in early Late Permian,a foreland basin in Mesozoic,and a strike-slip fault basin in Cenozoic.