不同构造变形带中“静水压力”的差别

ON THE DIFFERENCES OF HYDROSTATIC PRESSURE IN ZONES WITH DIFFERENT DEFORMATION PROPERTIES

地壳应力状态主要是由重力和构造作用力引起的,作者明确提出其静水压力部分是由重力所附加的静水压力和由构造作用力所附加的静水压力叠合而成。本文用有限元模型数学模拟实验证实,处在挤压变形带、剪切变形带到引张变形带(及地域)中岩石所承受的构造附加静水压力有逐次变小的规律性,利用这种规律可解释构造作用力影响成岩成矿作用的物理化学环境及制约其化学过程的动力学问题,为开展构造物理化学研究奠定了基础。

Stress state in the crust forms mainly Under the tectonic force and gravity. The author suggests that the hydrostatic pressure P of a point in the crust is a combination of two isotropic stresses in the stress field of both tectonic force and gravity. The former is referred to as a structural or tectonic additional hydrostatic pressure Ps and the latter as a gravity additional hydrostatic pressure PR·A formula of their relationship is listed below: where PRv is Poisson' s radio of rock, is density ofrock and h is depth, or thickness of overlying rock.The calculations by the use of NOLM 83 (Wang Ken et al) in finite -element model of a horizontal plate under horizontal force indicate that the additional hydrostatic pressure by tectonic force gradually decreases in the given order in the compressive zone (Pcs),the shear zone (Pshs) and the tensile zone (Pts ) at the same depth.The horizontal force in the X direction is 10MPa, and that in the Y direction is 60 MPa. The σ1 and σ3 in elements are given in Table 2. The medium principal stresses can be calculated by plane strain problem, and each Ps in elements can be obtained (Fig- 3). The average values of P, in the different deformation zones are PC =30.3 MPa, Pshs = 27.24 MPa and Pts = 23.81 MPa.If the model horizontal plate is at a depth of 3.5km, and the force is 35 MPa in X direction and 85 MPa in Y direction, we get 3 principal stresses in elements.Because PR≈25 MPa in the reseach area,the average values of PS of each element group are Pcs = 25.02 MPa, Pshs = 23.31 MPa and Pts = 18.61 MPa after PR is reduced from average principal stresses (P). The difference between PC and Pshs becomes smaller, but the difference between them and Pts is bigger.This research explains an important theoretical problem about how the tectonic force effects the physicochemical environment of petrogenesis and metallogenesis, and is a theoretical basis of tectonic physicochemistry or te-ctonophy sicochemistry(Lu Guxian, 1991),which is a new branch or research field in geology.