| GEOCHEMICAL CHARACTERISTICS OF THE EARLY MESOZOIC GRANODIORITES AND THEIR TECTONIC IMPLICATIONS |
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| 作者姓名： | PENG Touping * XI Xianwu WANG Yuejun PENG Bingxia and JIANG Zhimin |
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| 作者单位： | 1. Guangzhou Institute of Geochemistry，Chinese Academy of Sciences，Guangzhou，GD510640，China; 2. Graduate School of Academy of Chinese Academy of Sciences，Beijing 100039，China; 3. Geologic Engineering and Surveying Institute，Chang’an University，Xi’an，SX710054，China; 4. Tuha Petroleum Exploration and Development Bureau，Hami，XJ839009，China |
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| 基金项目： | 国家自然科学基金，中国科学院知识创新工程项目，CAS Key Laboratory of Isotope Geochronology and Geochemistry |
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| 摘 要： | The early Mesozoic granodiorites (ca. 165 Ma) in the northeastern Hunan Province (NEH) have SiO2=65.4-69.65%, K2O/Na2O=0.95-1.38 and K2O Na2O＞6%, A/CNK=0.96-1.13 and belong to metaluminous high-K calc-alkaline series. They are characterized by LREE and LILEs enrichment, and HFSE depletion with slightly negative Eu anomalies (Eu/Eu*=0.62-0.90). The initial 87Sr/86Sr ratios are in range from 0.711458 to0.717461, and εNd values vary from -9.4 to -12.3, distinct from those of the contemporaneous granodiorites mantle-derived from the Southeastern Hunan Province (SEH) (87Sr/86Sr(i)=0.707962～0.710396, εNd(t)=-6.98～-2.30).By contrast, such signatures are roughly similar to those of the neighboring other Mesozoic granitic plutons (Eu/Eu*=0.30-0.70; 87Sr/86Sr ＞0.710; εNd = -12 to -16) in South China Block (SCB), which have been interpreted as the remelting products of Precambrian basement. The Proterozoic lower-middle crust is an important contributor to the petrogenesis of these early Mesozoic granodiorites in the NEH. An intracontinental extension setting is present in the northeastern Hunan Province at that time due to the demand of enough thermal transfer.
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| 关 键 词： | 花岗闪长岩 碱性钙 中生代 湖南东北部 |
GEOCHEMICAL CHARACTERISTICS OF THE EARLY MESOZOIC GRANODIORITES AND THEIR TECTONIC IMPLICATIONS |
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| PENG Touping,Xi Xianwu,Wang Yuejun,Peng Bingxia,Jiang Zhimin.GEOCHEMICAL CHARACTERISTICS OF THE EARLY MESOZOIC GRANODIORITES AND THEIR TECTONIC IMPLICATIONS[J].Geotectonicaet Metallogenia,2005,29(1):58-70. |
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| Authors: | PENG Touping Xi Xianwu Wang Yuejun Peng Bingxia Jiang Zhimin |
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| Abstract: | The early Mesozoic granodiorites (ca. 165 Ma) in the northeastern Hunan Province (NEH) have SiO2=65.4-69.65%, K2O/Na2O=0.95-1.38 and K2O+Na2O＞6%, A/CNK=0.96-1.13 and belong to metaluminous high-K calc-alkaline series. They are characterized by LREE and LILEs enrichment, and HFSE depletion with slightly negative Eu anomalies (Eu/Eu*=0.62-0.90). The initial 87Sr/86Sr ratios are in range from 0.711458 to0.717461, and εNd values vary from -9.4 to -12.3, distinct from those of the contemporaneous granodiorites mantle-derived from the Southeastern Hunan Province (SEH) (87Sr/86Sr(i)=0.707962～0.710396, εNd(t)=-6.98～-2.30).By contrast, such signatures are roughly similar to those of the neighboring other Mesozoic granitic plutons (Eu/Eu*=0.30-0.70; 87Sr/86Sr ＞0.710; εNd = -12 to -16) in South China Block (SCB), which have been interpreted as the remelting products of Precambrian basement. The Proterozoic lower-middle crust is an important contributor to the petrogenesis of these early Mesozoic granodiorites in the NEH. An intracontinental extension setting is present in the northeastern Hunan Province at that time due to the demand of enough thermal transfer. |
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| Keywords: | calc-alkaline granodiorites lower-middle crustal source intracontinental extension early Mesozoic northeastern Hunan Province |
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