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张青: The dilemma of asymmetric porphyroclast systems and sense of shear

时间:2020-11-06来源:资源与环境工程学院

报告时间:2020年11月10日(星期二)15:00-17:00

报告地点:资环学院纬地楼3楼会议室

:张青 研究员

工作单位中国地质科学院地质力学研究所

举办单位:资源与环境工程学院

报告简介

Asymmetric porphyroclast systems have long been used as independent shear-sense indicators based on their clast-tail asymmetry and/or stair-stepping tail geometry. Over the last two decades, advances in exploring the mechanical behavior of rigid clasts in a viscous flow has shed new light on understanding the formation of porphyroclast systems embedded in noncoaxial viscous flow and subsequently quantifying many aspects of flow kinematics. Using examples from naturally deformed rocks combined with results from recent advances, our study indicates that: (1) in general, only porphyroclast systems composed of equant-shaped clasts can be treated as independent shear-sense indicators; (2) special attention should be given to β-type porphyroclast systems composed of high-angle intermediate aspect-ratio clasts, which may contain meaningful information on bulk flow kinematics; (3) bookshelf structures cannot serve as independent shear-sense indicators. Multi-criteria and thorough three-dimensional shape analyses are suggested for a proper interpretation of flow kinematics in ductile shear zones.

报告人简介

张青,男,1965年生,毕业于北京大学(1986,学士;1991,硕士)、美国明尼苏达大学(2006,博士)。先后在内蒙古师范大学、美国Carleton College、University of Iowa、University of  Minnesota、中国地质科学院地质力学研究所工作,兼任中国科学院大学博士生导师。学术专长为中小尺度构造地质学,研究方向包括韧性及韧?脆性地壳的构造形态、变形样式和运动学特征,显微尺度的构造变形机制和韧性组构的形成发育,韧性地壳的热年代学历史,造山带隆升的动力学机制。主持过多项国家级项目,在国际重要期刊发表过多篇学术论文。

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