摘要:
通过脆延性双层模型,在满足相似要求的前提下,模拟了三种边界条件下的上隆与伸展。模拟结果表明:两侧边界固定时,上隆能产生拱张断裂,然而它引起的侧向分流比较小,基本不能形成伸展;存在半开放或开放边界时,可以产生大规模的伸展,但伸展主要沿上隆早期产生的张裂进行,显然,上隆产生的张裂为后续伸展奠定了基础,同时上隆加速了延性层向开放边界方向流动,促进了伸展;另外,在上隆-伸展过程中普遍存在延性层被动上隆。这些实验结果说明,地幔主动上隆引起伸展是有条件的,需要边界条件的配合;被动上隆是普遍存在的,它是重力均衡作用的必然结果。
关键词:
-
上隆
/
-
伸展
/
-
物理模拟
/
-
边界条件
Abstract:
In the present paper,an experiment of the mantle uplifting and lateral extension is conducted under three different boundary conditions using a ductile/brittle double-layer physical model. The experiment results show that when the model is fixed on two sides,uplifting could cause stretch and faults with very small lateral flow. When the model are half or completely open,uplifting could cause very large extension,mainly in the direction of the faults early produced. Evidently the faults early formed in uplifting would create a favourable condition for the subsequent extension and the uplifting would accelerate the flow of ductile layer towards the direction of open boundary to promote further extension. In addition,some passive updoming of lower ductile layer is found where faults occurin the upper brittle layer in our models. It is therefore clear that no large extension should arise from mantle uplifting without favourable boundary conditions.
下载: