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No.79 (2005/3) >

Title :Fault development in the Thakkhola half graben : insights from numerical simulation
Authors :Chamlagain, Deepak
Hayashi, Daigoro
Authors alternative :林, 大五郎
Issue Date :Mar-2005
Abstract :Grabens of southern Tibet and the Himalaya represent the Cenozoic extensional tectonic phase, which has affected whole Tibet and northernmost part of the Himalaya. Thakkhola half graben, on the crest of the Himalaya, is one of the north trending grabens that define the Neogene structural pattern of the southern margin of the Tibetan Plateau and is seemingly enigmatic feature in a regionally contractional tectonic setting between the colliding plates. Two-dimensional, elastic, plane-strain, finite element models (FEMs) are generated to simulate the effects of geometry and rock properties on growth of graben faults and their configuration for the Thakkhola half graben evolution. The performed models have shown that the extensional graben faults form at the top of the overburden and propagate downward as we increased extensional displacement. Simulated models have clearly defined the graben bounding faults. Further they are able to suggest that natural grabens have multiple faults on each side rather than single fault. During progressive extensional displacement depth of faulting increases and deformation is mainly localized in downthrown block both in basement and syntectonic deposits. Syntectonic deposit is characterized by normal faulting in tensional tectonic stress field, which is a common feature of the small-scale graben at post rift deformation stage. The width and depth of graben are primarily controlled by the rheology of the upper elastic layer and syntectonic deposits. The applied rock layer properties are able to deduce the first order characteristics of the Thakkhola half graben. Therefore, this simulation constrains probable values for the rock layer properties controlling the Thakkhola half graben evolution. Assumption of the weak zone does not make significant difference on stress distribution and faulting. Thus it seems that the Thakkhola fault system only did not contribute to development of the half graben.
Type Local :紀要論文
ISSN :0286-9640
Publisher :琉球大学理学部
URI :http://hdl.handle.net/20.500.12000/2612
Citation :琉球大学理学部紀要 = Bulletin of the College of Science. University of the Ryukyus no.79 p.57 -90
Appears in Collections:No.79 (2005/3)

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