地壳深部“重力-构造力复合压力状态”研究和大别——苏鲁超高压变质形成深度的测算

发布时间：2018-04-23 16:50

本文选题：大别超高压变质带 + 重力-构造力复合的静水压力模型　；参考：《地学前缘》2017年02期

【摘要】：讨论了地壳深部岩石处于"重力-构造力复合的静水压力模型"。此模型的基本认识为,地壳深部压力是由重力应力和构造应力引起的两部分各向等应力合成的,构造应力场的静水压力部分被称为"构造附加静水压力"。遵循这一认识,需要从总静水压力中先去掉构造附加静水压力,进而用构造校正[深度=重力引起压力/(总压力-构造附加的压力)]的方法,进行形成深度的测算。考虑岩石作为黏弹性体的应力-应变关系,作者用黏弹性本构方程,获得大别地区英山县含柯石英榴辉岩的成岩深度≥30km,安徽岳西碧溪岭地区含柯石英榴辉岩深度为23~53km,河南新县地区的含柯石英榴辉岩成岩深度为36~40km。再进一步用变质深度的流变学公式,在黏性系数0.2×10~(23)条件下,推算出超高压变质岩形成深度约50~55km。可见,大别超高压变质岩形成深度介于23~55km,而不是前人认为的超过100km甚至更深,由此,"深俯冲-折返"模式需要科学的论证。本研究为高压-超高压变质的"构造增压壳内成因"提供了一些依据。
[Abstract]:This paper discusses the hydrostatic pressure model of deep crustal rocks in the composite of gravity and tectonic force. The basic understanding of this model is that the deep crustal pressure is composed of two isotropic stresses caused by gravity stress and tectonic stress, and the hydrostatic pressure part of tectonic stress field is called "tectonic additional hydrostatic pressure". Considering the stress-strain relation of rock as viscoelastic body, the author uses viscoelastic constitutive equation. Furthermore, using the rheological formula of metamorphic depth and under the condition of viscosity coefficient 0.2 脳 10 ~ (3), the formation depth of ultrahigh pressure metamorphic rocks is estimated to be about 50 ~ 55 km. It can be seen that the formation depth of Dabie ultrahigh pressure metamorphic rocks is between 2355 km, rather than the former thought that the depth is higher than 100km or even deeper. Therefore, the "deep subduction-reentry" model needs scientific argumentation. This study provides some basis for the formation of structural pressurized crust in high pressure-ultra-high pressure metamorphism.
【作者单位】：中国地质科学院地质力学研究所;东华理工大学放射性地质与勘探技术国防重点学科实验室;中国地质大学(北京)地球科学与资源学院;北京大学地球与空间科学学院;中国地质大学(武汉)地球科学学院;
【基金】：国土资源部科技发展重点项目“地壳深部压力状态与超高压岩石形成研究”(2002201,2002—2005) 国家科委基础研究特别项目(国科高字[1994]83号) 国家计委科技找矿项目(JG947110) 国家自然科学基金项目(49572149)
【分类号】：P588.3

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