微观结构超压机制与超高压矿物的形成  

Micro-structural overpressure mechanizm and the ultra-high pressure metamorphic rocks formation.

作　　者：武红岭[1] 池顺良 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]鹤壁市地震局,鹤壁458000

出　　处：《岩石学报》2003年第4期739-744,共6页Acta Petrologica Sinica

基　　金：国家自然科学基金(批准号:19972064);国土资源部科技发展计划项目(批准号:2002201)资助

摘　　要：提出了由岩石及矿物的结构形态、岩石力学性质不同引起的微结构超压机制。对影响结构超压的诸因素(弹性参数、热物理性质)进行了数值模拟实验和定量分析。研究结果表明,结构压力对超高压岩石、矿物的形成具有重要的意义。结构压力随弹性模量差异、围限压力、温度改变量及热膨胀系数差异的增加而增大。在岩石、矿物的弹性模量相差5倍的条件下,结构附加压力可达到静岩压力的45％左右。如果再考虑热膨胀系数不同及降温引起的附加压力,在较一般的情况下,60公里左右深处就有可能具备柯石英等超高压矿物形成的下限压力条件。A new mechanism of micro-structural overpressure caused by the rock or mineral differences in structure and mechanical properties is applied to study the producing of ultra-high pressure metamorphic (UHPM) rocks and minerals. Using numerical simulated method we research some factors (rocks mechanical and thermal physical properties) that control the structural pressure and affect UHP metamorphic rock formation. The results show that the micro-structural pressure could play an important role to form UHP metamorphic rocks. The magnitude of micro-structural pressure between the rock's materials increases with some factors such as the differences in elastic modulus and thermal expansion coefficients, boundary pressure and temperature changes. In some conditions, for example, we suppose that the differences rate between the maximum elastic modulus and the minimum one in rocks or minerals is 5 times, it would cause the structural pressure of about 45 percent of the lithostatic pressure at the same depth. If the structural pressure due to the differences in the thermal expansion coefficients and the temperature changes are also added, on general conditions the total pressure at,about 60 km depth could meet the lower limited requirement of growth of coesite in ultra-high pressure rocks.

关 键 词：超高压矿物 结构超压 影响因素 成岩深度 

分 类 号：P589.1[天文地球—岩石学]