Microdiamonds, their classification and tectonic implications for the host eclogites from the Dabie and Su-Lu regions in central eastern China

Mineralogical Magazine - Tập 69 Số 4 - Trang 509-520 - 2005
Shutong Xu1, Yi-Can Liu2, Guan-Bao Chen3, Shouyuan Ji4, Pei Ni4, W.-Q. Xiao5
1Laboratory of Continental Dynamics of Ministry of Land and Resources of China, Beijing, 100037, China
2China University of Sciences and Technology, Hefei, 230026, China
3Anhui Institute of Geology, 19 Ningguo Road, Hefei, 230001, China
4Department of Earth Sciences, Nanjing University, Hankou Road, Nanjing, 210008, China
5Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China

Tóm tắt

AbstractWe have found >10 in situ microdiamonds in thin sections of eclogites from the Dabie and Su-Lu regions of central eastern China since the first occurrence of microdiamond in eclogites from the Dabie Mountains (DMT) reported in 1992. The microdiamonds are found not only in the central part but also in the northern part of the DMT. Several free crystals have been recovered from the crushed eclogites from the central DMT. Most in situ microdiamonds are inclusions in garnets but a few larger ones are intergranular. Most of the diamondiferous eclogites in the central part of the DMT are associated with coesite. Most importantly, the observation of microdiamonds in northern Dabie lead us to question the supposition that this is a low-P metamorphic terrane. All the diamondiferous eclogites from both the north and central DMT are of continental affinity as demonstrated by their negative εNd values. Therefore, both the north and central eclogite belts in the DMT are considered to be from the deep subducted terrane. Five in situ microdiamonds and two free crystals are first reported in this paper. The dimensions of the in situ microdiamonds are 30–180 µm and the free crystals are up to 400–700 mm across. All the microdiamonds are confirmed as such by Raman spectroscopy. The results of an infrared spectroscopic investigation on two larger free crystals and two in situ microdiamonds show that all the microdiamonds from both the Dabie and Su-Lu regions are mixed types IaA and IaB diamonds and there is no indication of any synthetic microdiamonds in our samples because such synthetic microdiamonds are always rich in type Ib.

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Tài liệu tham khảo

Xu, 2002, Architecture and Kinematics of the Dabie Mountains Orogen: Hefei, 133

10.1126/science.248.4958.993

Xu, 1992, Diamond from the Dabie Shan metamorphic rocks and its implication for tectonic setting, Science, 256, 80, 10.1126/science.256.5053.80

10.1111/j.1525-1314.1996.00319.x

Xu, 2005, Architecture and kinematics of the Dabie orogen, central eastern China, Acta Geologica Sinica, 3, 356

10.1130/0091-7613(1995)023<0597:MIHGMR>2.3.CO;2

Zhang, 1993, Discovery of coesite from eclogite in Henan, central China and its geological significance, Acta Petrologica Sinica, 9, 186

10.1007/978-3-662-03000-4

10.1130/0091-7613(2002)030<0959:MIAMGW>2.0.CO;2

10.1007/BF02911943

10.1017/CBO9780511573088.012

10.1038/343742a0

10.1130/0091-7613(1989)017<1085:CBEFTD>2.3.CO;2

Massonne, 1999, Proceedings of the 7th International Kimberlite Conference, 533

Orlov, L. (1973) MИHPAΓИ ЯπMA3A [Mineralogy of Diamonds] (Translated to Chinese, 1977), Published in Beijing, 175 pp.

10.1127/ejm/1/4/0595

10.1016/S0016-7037(98)00266-X

Xie, 1999, Physics of the Gem Mineralogy of China, 272

Xu, 1987, Etude tectonique et microtectonique de la Chaine Paleozoique et Triassique des Qinglings (Chine), 95

Wang, 1993, Discovery of coesite-bearing eclogite in south Henan, Acta Petrologica Sinica, 9, 181

10.1038/35037566

Wang, 1996, Tectonic implication of UHP rocks from the Dabie Mountains, Science in China (Series D), 39, 311

Zhai, 1995, Petrologic-tectonic units in the coesite-bearing metamorphic terrain of the Dabie Mountains, central China and their geotectonic implications, Journal of southeast Geoscience, 11, 1

Xu, 2002, Academic Papers for 80th Anniversary of the Geological Society of China, 92

Carmichael, 1960, Igneous Petrology., 739

Cong, 1995, Petrogenesis of ultrahigh-pressure rocks and their country rocks in Shuanghe of Dabieshan, central China, European Journal of Mineralogy, 7, 119, 10.1127/ejm/7/1/0119

10.1007/BF03184213

10.1130/0091-7613(1991)019<0933:RUPCBE>2.3.CO;2

Wang, 1994, Annual Report of the Laboratory of Lithosphere Tectonic Evolution (1993-1994), 37

Yang, 2002, Discovery of diamond in North Qinling: evidence for a giant UHPM belt across central China and recognition of Paleozoic and Mesozoic dual deep subduction between North China and Yangtze plates, Acta Geologica Sinica, 76, 484

Cong, 1996, Ultrahigh-pressure Metamorphic Rocks in Dabie-Sulu Region of China, 128

Yang, 1999, The discovery of diamond in the eclogite from the Sulu region, Earth Science Front, 6, 69

10.1111/j.1440-1738.1994.tb00099.x

10.1016/B978-0-08-034874-2.50011-3

10.1180/minmag.1996.060.401.12

Xu, 1994, Tectonic regime and evolution of Dabie Mountains, 175

10.1007/BF02884690

Li, 1996, Chronology of ultrahigh-pressure metamorphism in the Dabie Mountains and Sulu terrane: (i) Sm-Nd isotope system, Science in Chian (Series D), 39, 597

10.1038/270141a0

Xu, 2001, Paradoxes in Geology, 323

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Mineralogical Magazine

Tập 69 Số 4

509-520

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