STUDY OF SOME TYPICAL INCLUSION PATTERNS IN STRONGLY PARACRYSTALLINE-ROTATED GARNETS

作     者：SCHONEVELD, C 

作者机构：STATE UNIV LEIDENINST GEOL & MINERALLEIDENNETHERLANDS 

出 版 物：《TECTONOPHYSICS》 (地质构造物理学)

年 卷 期：1977年第39卷第1-3期

页      面：453-471页

核心收录：

学科分类：0709[理学-地质学] 081803[工学-地质工程] 07[理学] 08[工学] 0708[理学-地球物理学] 0818[工学-地质资源与地质工程] 

摘      要：Heterogeneous strain of the matrix around rotating garnets gives rise to quartz-filled pressure shadows. It is shown that paracrystalline rotating garnets overgrow the pressure shadows. The incorporated parts of these pressure shadows, characterized by relatively large quartz inclusions, continuously rotate away from their sites of inclusion, while new parts of these pressure shadows are overgrown. This process leads to spirally arranged quartz zones in the garnets, not be confused with the also spirally arranged relicts (S i ) of the foliation. The S i trails always intersect the quartz spiral. At the point of intersection the S i trails show their strongest curvature. The presence or absence and the detailed morphology of the quartz spirals depends on factors such as the ratio of growth rate to rotation rate ( g r ). In the absence of quartz spirals there is sometimes a double spiral composed of opaques only. It is also shown that for certain garnets this absence of the quartz spiral may result in an S i inclusion pattern with an apparently spherical form. An alternative explanation is thus presented for the spherically arranged inclusions described by Harvey and Ferguson (1973) and attributed by them to the force of crystallization.