Mineral Assemblages and Their Evolution of Clinopyroxenite Xenolith in Early Jurassic Intrusive Complex from Xu-Huai Region, Central China
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摘要: 对徐—淮地区早侏罗世侵入杂岩中尖晶石单斜辉石岩捕虏体的岩石学和矿物学研究表明, 镁铁尖晶石和富铝单斜辉石矿物组合代表了更早期地幔岩浆在下部地壳或上地幔顶部的堆积体, 其形成的温压条件为0.90 GPa和835℃; 以尖晶石转变成石榴石和单斜辉石+石榴石+刚玉组合为代表的矿物组合(Ⅱ) 反映了尖晶石单斜辉石岩形成后又经历了高压变质作用, 所估算的温压条件为1.40~1.6 5 GPa和900~1 000℃; 晚期退变角闪石的形成表明尖晶石单斜辉石岩又遭受了角闪岩相的退化变质作用, 估算的温压条件为0.70 GPa和670~740℃.该类捕虏体的发现对认识大别—苏鲁超高压变质带的深部俯冲方向及其范围具有重要意义.Abstract: Petrology and mineralogy of spinel-clinopyroxenite xenolith in Early Jurassic intrusive complex from Xu-Huai region, central China indicate that Mg-Fe spinel and Al-clinopyroxene assemblage could be present as the cumulate of the underplating magma in the lower crust or the most upper mantle, which were formed under 0.90 GPa and 835 ℃; that the mineral assemblage (Ⅱ) represented by spinel-garnet transition and clinopyroxene (Cpx) +garnet (Grt) +corundum (Co) assemblage could reflect that the spinel-clinopyroxenite was subjected to high pressure metamorphism with 1.40-1.65 GPa and 900-1 000 ℃; and that the occurrence of retrogressive amphibole implies that the spinel-clinopyroxenite could undergo the amphibolite facies retrogressive metamorphism with 0.70 GPa and 670-740 ℃. The discovery of the xenolith is of important implication for us to recognize the deep subduction direction and the scale of the Dabie-Sulu ultrahigh-pressure (UHP) metamorphic belt.
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图 1 早侏罗世侵入杂岩和大别—苏鲁超高压变质带分布
1.高温(超) 高压变质带; 2.低温高压变质带; 3.秦岭—桐柏深变质杂岩; 4.北淮阳浅变质杂岩; 5.古生界; 6.断层; 7.岩体; 8.断层
Fig. 1. Distribution of Early Jurassic intrusive complex and Dabie-Sulu UHP metamorphic belt
图 2 徐—淮地区地质略图
1.中生代和更年轻的地层; 2.晚古生代地层; 3.晚元古和早古生代地层; 4.逆冲断层; 5.正断层; 6.其他断层; 7.地层界线; 8.侵入体
Fig. 2. Geologic sketch map in Xu-Huai region
图 3 捕虏体产状和矿物组合的图片
a.单斜辉石岩的野外照片; b.捕虏体中尖晶石-石榴石转变的背散射图像; c.捕虏体中的尖晶石、刚玉和石榴石组合.Grt.石榴石; Sp.尖晶石; Co.刚玉; Cpx.单斜辉石
Fig. 3. Photomicrographs showing mineral microstructures
表 1 单斜辉石岩中的矿物成分
Table 1. Mineral composition in clinopyroxenite xenolith
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[1] Cong B, Wang Q. The Dabie-Sulu UHP rocks belt: review and prospect[J]. Chinese Science Bulletin, 1999, 44 (12): 1074-1086. doi: 10.1007/BF02886130 [2] Su W, You Z, Wang R, et al. Quartz and clinoenstatite exsolution in clinopyroxenes of garnet-pyroxenolite from the north Dabie Mountains, eastern China[J]. Chinese Science Bulletin, 2001, 46(17): 1482-1485. doi: 10.1007/BF03187037 [3] Tsai C H, Liou Z G. Eclogite-facies relics and inferred ultrahigh-pressure metamorphism in the north Dabie complex, central-eastern China[J]. Am Mineral, 2000, 85: 1-8. doi: 10.2138/am-2000-0101 [4] 许文良, 王冬艳, 刘晓春, 等. 徐—淮地区早侏罗世侵入杂岩体中榴辉岩类包体的发现及其地质意义[J]. 科学通报, 2002, 47(8): 618-622. https://www.cnki.com.cn/Article/CJFDTOTAL-KXTB200208014.htmXU W L, WANG D Y, LIU X C, et al. Discovery of eclogite inclusions and its geological significance in Early Jurassic intrusive complex in Xuzhou- northern Anhui, eastern China[J]. Chinese Science Bulletin, 2002, 47 (14): 1212-1216. https://www.cnki.com.cn/Article/CJFDTOTAL-KXTB200208014.htm [5] 王桂梁, 姜波, 曹代勇, 等. 徐州-宿州弧形双冲-叠瓦扇逆冲断层系统[J]. 地质学报, 1998, 72(3): 228-236. doi: 10.3321/j.issn:0001-5717.1998.03.004WANG G L, JIANG B, CAO D Y, et al. On the Xuzhou-Suzhou arcuate duplex-imbricate fan thrust system [J]. Acta Geological Sinica, 1998, 72(3): 228-236. doi: 10.3321/j.issn:0001-5717.1998.03.004 [6] 林景仟, 谭东娟, 历建华, 等. 华北陆台南缘早侏罗世徐州班井侵入杂岩体[J]. 长春科技大学学报, 2000, 30 (3): 209-214. doi: 10.3969/j.issn.1671-5888.2000.03.001LIN J Q, TAN D J, LI J H, et al. Early Jurassic Banjing intrusive complex of southern marginal zone of North China block, Xuzhou[J]. J Changchun Univ Sci Tech, 2000, 30(3): 209-214. doi: 10.3969/j.issn.1671-5888.2000.03.001 [7] 林景仟, 谭东娟, 金烨. 鲁西地区中生代火成活动的40Ar/39Ar年龄[J]. 岩石矿物学杂志, 1996, 15(3): 213-220. https://www.cnki.com.cn/Article/CJFDTOTAL-YSKW603.002.htmLIN J Q, TAN D J, JIN Y. 40Ar/39Ar ages of Mesozoic igneous activities in western Shandong[J]. Acta Petrologica et Mineralogica, 1996, 15(3): 213-220. https://www.cnki.com.cn/Article/CJFDTOTAL-YSKW603.002.htm [8] 鄂莫岚, 赵大升. 中国东部新生代玄武岩及深源岩石包体[M]. 北京: 科学出版社, 1987.E M L, ZHAO D S. Cenozoic basalts and the deep-seated xenoliths in eastern China[M]. Beijing: Science Press, 1987. [9] Xu X, O'Reilly S Y, Griffin W L, et al. The nature of the Cenozoic lithosphere at Nushan, eastern China[A]. In: Flower M F J, Chung S L, Lo C H, et al, eds. Mantle dynamics and plate interaction in east Asia[C]. Geodynamics Series: American Geophysical Union, 1998, 27: 167-195. [10] Coleman R G, Lee D E, Beatty L B, et al. Eclogites and eclogites: their differences and similarities[J]. Geol Soc Am Bull, 1965, 76: 483-508. doi: 10.1130/0016-7606(1965)76[483:EAETDA]2.0.CO;2 [11] 从柏林, 张雯华. 榴辉岩的石榴子石[J]. 科学通报, 1977, 22(9): 413-416. https://www.cnki.com.cn/Article/CJFDTOTAL-KXTB197709011.htmCONG B L, ZHANG W H. Garnet in eclogite[J]. Chinese Science Bulletin, 1977, 22(9): 413-416. https://www.cnki.com.cn/Article/CJFDTOTAL-KXTB197709011.htm [12] Leake B E, Woolley A R, Arps C E S, et al. Nomenclature of amphibole: report of the subcommittee on amphiboles of the international mineralogical association, commission on new minerals and mineral names[J]. Am Mineral, 1997, 82: 1019-1037. [13] Boyd F R. A pyroxene geotherm[J]. Geochim et Cosmochim Acta, 1973, 37: 2533-2546. doi: 10.1016/0016-7037(73)90263-9 [14] Nimis P. A clinopyroxene geobarometer for basaltic systems based on crystal-structure modeling[J]. Contrib Mineral Petrol, 1995, 121: 115-125. doi: 10.1007/s004100050093 [15] Herzberg C. Pyroxene geothermometry and geobarometry: experimental and thermodynamic evalution of some subsolidus phase involving clinopyroxenes in the system CaO-MgO-Al2O3-SiO2[J]. Geochim et Cosmochim Acta, 1978, 42: 945-957. doi: 10.1016/0016-7037(78)90284-3 [16] O'Neil H C. The transition between spinel lherzolite and garnet lherzolite, and its use as a geobarometer[J]. Contrib Mineral Petrol, 1981, 77: 185-194. doi: 10.1007/BF00636522 [17] 樊祺诚, 刘若新, 谢鸿森, 等. 上地幔尖晶石—石榴石相转变实验研究及其意义[J]. 中国科学(D辑), 1997, 27 (2): 109-114. https://www.cnki.com.cn/Article/CJFDTOTAL-JDXK199702002.htmFAN Q C, LIU R X, XIE H S, et al. Experimental research on spinel-garnet phase transition in the upper mantle and its significance[J]. Science in China(Series D), 1997, 27(2): 109-114. https://www.cnki.com.cn/Article/CJFDTOTAL-JDXK199702002.htm [18] 李天福, 马鸿文, 白志民. 汉诺坝地区上地幔尖晶石—石榴石相转变带温压条件[J]. 现代地质, 1999, 13(1): 66-72. https://www.cnki.com.cn/Article/CJFDTOTAL-XDDZ901.009.htmLI T F, MA H W, BAI Z M. Temperature and pressure states of spinel-garnet transition zone beneath Hannuoba area[J]. Geoscience, 1999, 13(1): 66-72. https://www.cnki.com.cn/Article/CJFDTOTAL-XDDZ901.009.htm [19] Ionov D A, Ashchepkov I V, Stosch HG, et al. Garnet peridotite xenoliths from the Vitim volcanic field, Baikal region: the nature of the garnet-spinel peridotite transition zone in the continental mantle[J]. J Petrol, 1993, 34: 1141-1175. doi: 10.1093/petrology/34.6.1141 [20] Gasparik T. Experimentally determined stability of clinopyroxenes+ garnet+ corundum in the system CaO-MgO-Al2O3-SiO2[J]. Am Mineral, 1984, 69: 1025-1035. [21] Johnson M C, Rutherford M J. Experimental calibration of an aluminum-in-hornblende geobarometer applicable to calc-alkaline rocks[J]. EOS, 1988, 69: 1511. [22] Wang Q, Cong B. Exhumation of UHP terranes: a case study from the Dabie Mountains, eastern China[J]. Inter Geol Rev, 1999, 41: 994-1004. doi: 10.1080/00206819909465185 [23] Suo S T, Zhong Z Q, You Z D. Extensional deformation of post ultrahigh-pressure metamorphism and exhumation process of ultrahigh-pressure metamorphic rocks in the Dabie massif[J]. Science in China(Series D), 2000, 43 (3): 225-236. doi: 10.1007/BF02906818 [24] Jahn B. Sm-Nd isotopetracer study of UHP metamorphic rocks: implications for continental subduction and collisional tectonics[J]. Inter Geo Rev, 1999, 41: 859-885. doi: 10.1080/00206819909465175 [25] Li S, Jagoutz E, Lo C H, et al. Sm/Nd, Rb/Sr and 40Ar/39Ar isotopic systematics of the ultrahigh-pressure metamorphic rocks in the Dabie-Sulu belt, Central China: a retrospective review[J]. Inter Geol Rev, 1999, 41: 1114-1124. doi: 10.1080/00206819909465195 -
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