e="MARGIN: 0cm 0cm 0pt; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-pagination: widow-orphan; mso-outline-level: 2" class=MsoNormal>e="FONT-FAMILY: 宋体; COLOR: black; FONT-SIZE: 12pt; mso-bidi-font-family: 宋体; mso-font-kerning: 18.0pt" lang=EN-US>Genetic Mineralogy and Metamorphic Evolution of Mafic High-Pressure (HP) Granulites from the espace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />
详细信息
- 责任者：Liu Pinghua (Institute of Geology ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Liu Fulai
- 刊名：Acta Petrologica Sinica
- 出版年：2010
- 卷期：26(7)
- 关键词：麻粒岩 ; granulite ; 山东半岛 ; Shandong Peninsula
- 页码：p.2039-2056
- 图表：13 illus., 5 tables, 75 refs.
- 分类号：0802
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
EnChDivSummary name="EnDivSummary">Mafic high-pressure（HP）granulites as enclaves and irregular vein-like blocks are widespread distributed in TTG gneiss in the Pingdu-Laixi-Laiyang-Yantai area of Shandong Peninsula,southeastern Sino-Korean craton.In this paper,four stages of the metamorphic evolution have been identified in mineral assemblages,including early prograde metamorphic stage（M1）,peak HP granulite-facies metamorphic stage（M2）,near isothermal decompression granulite-facies retrograde stage（M3）,and late amphibolite-facies retrograde stage（M4）.The P-T conditions for each metamorphic stage were estimated using thermodynamical and experimental geothermometers and geobarometers.The core of garnet,together with mineral inclusions,is regarded as a prograde assemblage（M1）of garnet+clinopyroxene+plagioclase±quartz,which formed at 740~770 ℃ and 0.9~1.0 GPa.The peak HP granulite-facies metamorphism（M2）is defined by high-Ca cores in garnet,high-Al cores in clinopyroxene and high-Na cores in plagioclase ±quartz as matrix minerals,yielding 850~880 ℃ and 1.45~1.65GPa.Symplectites or coronas of orthopyroxene+clinopyroxene+plagioclase+magnetite±amphibole around garnet porphyroblasts indicate garnet decompressional reactions（M3）occurring at P-T conditions of 780~830 ℃ and 0.65~0.85 GPa.Symplectites of amphibole+plagioclase+magnetite±quartz surrounding garnet formed at a cooling retrograde stage（M4）with P-T conditions of 590~650 ℃ and 0.62~0.82 GPa.These data indicate that the mafic HP granulites record an integrated P-T path including prograde,near-isothermal decompression（ITD）and near-isobaric cooling（IBC）evolutional process.The clockwise ITD and IBC P-T paths of the mafic HP granulites in the Shandong Peninsula support a geodynamic model of crust thickening followed by extension in a continent-continent collisional orogen.