Petrology, geochemistry and geodynamics of basic granulite from the Altay area, North Xinjiang, China

INTRODUCTION Due to granulites representing products of thedeeper lower crust-upper mantle and having geneticassociation with early crustal evolution and forma-tion of large-scale metallogenic-forming and nonmetallogenic-forming belts, the study of granulitesin the world has resulted in much recent attention(Zhai and Liu, 2001; Liu and Zhou, 1994; Yu et al.,1998; 2003; Li et al., 2000; Zhang et al., 2001; Yuet al., 2002; Bingen and Stein, 2003; Blein et al.,2003; Garcia et al., …     

重力场的时间变化与地球动力学

利用现代高精度重力场信息研究地球动力学问题是近年来国际地学领域前沿热点,除地震测量外,重力场为人们准确了解和深刻认识地球深内部构造提供又一有效工具。文章简要概述了利用超导重力仪开展重力场研究的背景和作用,介绍了国际发展现状和趋势以及我院近年来在知识创新工程重要方向性项目的支持下取得的主要研究成果,最后对如何进一步发挥重力场在地球动力学和国家需求方面的作用提出了几点建议。     

板块构造正反说

本世纪６０年代板块构造概念的出现标志着地球科学革命性进步。３０年来,板块构造学说得到了很大发展,但仍存在一些问题和缺陷,它在海洋和大陆上遇到了许多问题。在研究地球演化的过程中,又在古地磁学与古气候学上遇到了不解之谜,随着研究的深入和技术的发展,有可能建立新的全球理论来取代板块构造     

Petrology,geochemistry and geodynamics of basic granulite from the Altay area,North Xinjiang,China

The basic granulite of the Altay orogenic belt occurs as tectonic lens in the Devonian medium- to lower-grade metamorphic beds through fault contact. The Altay granulite (AG) is an amphibole plagioclase two-pyroxene granulite and is mainly composed of two pyroxenes, plagioclase, amphibole and biotite. Its melano-minerals are rich in Mg/(Mg Fe2 ),and its amphibole and biotite are rich in TiO2. The AG is rich in Mg/(Mg Fe2 ), Al2O3 and depletion of U, Th and Rb contents. The AG has moderate ∑REE and LREE-enriched with weak positive Eu anomaly. The AG shows island-arc pattern with negative Nb, P and Ti anomalies, reflecting that formation of the AG -05 be associated with subduction. Geochemical and mineral composition data reflect that the protolith of the AG is calc-alkaline basalt and formed by granulite facies metamorphism having peak P-T conditions of 750 ℃-780 ℃ and 0.6-0.7 Gpa. The AG formation underwent two stages was suggested. In the early stage of oceanic crustal subduction, calc-alkaline basalt with island-arc environment underwent granulite facies metamorphism to form the AG in deep crust, and in the late stage, the AG was thrust into the upper crust.