Transformation of Chromium Spinel and Garnet: Evidence of CCSD-PP3 Ultramafic Rocks Processed UHP Metamorphism
-
摘要: PP3超镁铁岩主要岩石类型有纯橄岩和石榴石橄榄岩,两者为渐变,主要矿物为橄榄石、铬尖晶石、石榴石、单斜辉石和斜方辉石.铬尖晶石的Cr#[Cr/(Cr+Mg) ×100]从51~89变化,TiO2和MnO2值分别低于0.26%和0.46%.铬尖晶石矿物表现为4期次演化的特点,反映了从岩浆期、榴辉岩相、角闪岩相和绿片岩相演化特征.随着超镁铁岩的演化,铬尖晶石表现为Cr#不断增大,而Mg#[Mg×100/(Mg+Fe2+) ]不断减少、氧逸度不断增加的过程.PP3铬尖晶石反映了地幔来源,为大陆岩石圈超镁铁岩特征,后期随折返而演化.从石榴石与铬尖晶石相互转变过程看出,PP3超镁铁岩经历了深度加大的过程,超镁铁岩曾经到达100km以上的岩石圈地幔深处.在绿片岩相-绿片角闪岩相变质过程中,铬尖晶石中Cr、Mg和Al减少,Fe相对增加,产生富Cr尖晶石变质作用样式.晚期剪切变形等次生变化影响了铬尖晶石矿物成分.Abstract: The ultramafic rocks in the CCSD-PP3 (China Continental Scientific Drilling) drill-hole consist of dunite and garnet peridotite with a gradual margin between them. The main minerals in the rocks are olivine,chromium spinel,diopside,endiopside,and/or garnet,orthopyroxene,amphibole and phlogopite. Chromium spinels in PP3 ultramafic rocks can be divided into 4 groups with a varied composition,Cr# (molar 100Cr/(Cr+Mg)) from 51 to 89,which consists of four evolution stages of the ultramafic rocks. The 4 stages are partial melting,eclogite facies,amphibole facies and greenschist facies. When the Cr# of chrome spinels increases,the Mg# (molar 100Mg/(Mg+Fe 2+)) of chromium spinels decreases,but oxygen fugacity rises. Compositions of the chromium spinels reflect that the rocks originating from the shallow mantle have subducted to a depth of over 100 km and have then been exhumed to the surface. During the subsequent greenschist-facies and amphibole- facies metamorphism,the chromium spinels lost some Cr,Mg and Al,but gained relatively more Fe.
-
Key words:
- garnet peridotite /
- chromium spinel /
- UHP /
- CCSD-PP3 /
- Sulu
-
图 1 石榴石橄榄岩(a)和(铬尖晶石) 纯橄榄岩(b)
Fig. 1. Garnet peridotite (a) and chromium spinel peridotite (b)
2A 不同期次的铬尖晶石在岩石中的分布
1.尖晶石呈条带状分布(单偏光); 2.B15R22P1尖晶石与镍黄铁矿(反射光); 3.石榴石与角闪石(单偏光); 4.铬尖晶石裂理(反射光); 5.橄榄石中尖晶石(单偏光); 6.尖晶石中石榴石(单偏光); 7.石榴石边部尖晶石和角闪石(反射光); 8.石榴石中部和边部尖晶石(单偏光)
2A. A Distribution of chromium spinels in different rocks
2B 不同期次的铬尖晶石在岩石中的分布
1.石榴石中尖晶石(SEM); 2.“排骨状”铬尖晶石(SEM); 3.斜方辉石出溶单斜辉石和尖晶石(SEM); 4.角闪石和尖晶石(SEM); 5.尖晶石与石榴石共生(SEM); 6.尖晶石中单斜辉石(SEM); 7.尖晶石的环状结构(SEM); 8.橄榄石外部的尖晶石(SEM)
2B. B Distribution of chromium spinels in different rocks
2C 不同期次的铬尖晶石在岩石中的分布
1.尖晶石的环状结构(SEM); 2.尖晶石的环状结构(SEM); 3.角闪石中尖晶石(SEM); 4.尖晶石边部金云母(单偏光); 5.劈理发育的蛇纹石中尖晶石(SEM); 6.被橄榄石交代的尖晶石(SEM); 7.尖晶石中橄榄石(单偏光); 8.尖晶石中单斜辉石(SEM)
2C. C Distribution of chromium spinels in different rocks
图 4 铬尖晶石Mg#与Fe3+/(Fe3++Fe2+) 关系
Fig. 4. Chromite corelationship diagram of Mg# and Fe3+/(Fe3++Fe2+)
图 5 铬尖晶石成分图解(a)和铬尖晶石Cr2O3与斜方辉石Al2O3关系(b)
图a据Guillot et al., 2001;图b据Kepezhinskas and Defant, 1997
Fig. 5. Composition of chromium spinels (a) and diagram of Cr2O3 of chromium spinels and Al2O3 of orthopyroxene (b)
图 6 橄榄石Mg#和铬尖晶石Cr#图解(Pearce et al., 2000)
Fig. 6. Plot of chromium spinel Cr# against olivine Mg# for the PP3 peridotites
图 7 铬尖晶石Cr、Al和Fe3+含量与铬铁矿比较
Fig. 7. Chromium spinel compositions shown in Cr, Al and Fe3+ ternary diagram
图 8 铬尖晶石矿物Cr#演化变化(据Klemme, 2004修改)
Fig. 8. Evolution of Cr# of PP3 chromium spinels
图 11 PP3铬尖晶石TiO2与Cr#图解(Pearce et al., 2000)
Fig. 11. Diagram of TiO2 and Cr# of PP3 chrome spinel
表 1 铬尖晶石电子探针分析结果
Table 1. Composition of chrome spinels
表 2 32个氧原子时铬尖晶石分子式和参数
Table 2. Molecular formula and parameter of chrome spinels
-
Abe, N., Arai, S., Saeki, Y., 1992. Hydration processes in the arc mantle: Petrology of the Megata peridotite xenoliths, the northeast Japan arc. Jour. Min. Petr. Econ. Geol. , 87: 305-317. doi: 10.2465/ganko.87.305 Arai, S., 1991. The Circum-Izu Massive peridotite, central Japan, as back-arc mantle fragments of the Izu-Bonin arc system. In: Peters, T. j., Nicolas, A., Coleman, R.G., eds., Ophiolite genesis and evolution of the oceanic lithosphere. Kluwer, Dordrecht, 807-822. Arai, S., 1992. Chemistry of chromium spinel in volcanic rocks as a potential guide to magma chemistry. Mineralogical Magazine, 56: 173-184. doi: 10.1180/minmag.1992.056.383.04 Arai, S., 1994. Characterization of spinel peridotites by olivinespinel compositional relationships: Review and interpretation. Chemical Geology, 113: 191-204. doi: 10.1016/0009-2541(94)90066-3 Arai, S., Okada, H., 1991. Petrology of serpentine sandstone as a key to tectonic development of serpentine belts. Tectonophysics, 195: 65-81. doi: 10.1016/0040-1951(91)90144-H Barnes, S.J., Roeder, P.L., 2001. The range of spinel compositions in terrestrial mafic and ultramafic rocks. J. Petrol. , 42: 2279-2302. doi: 10.1093/petrology/42.12.2279 Bloomer, S.H., Fisher, R.L., 1987. Petrology and geochemistry of igneous rocks from the Tonga Trench—A nonaccreting plate boundary. Journal of Geology, 95: 469-495. doi: 10.1086/629144 Chen, S.Z., Yang, J.S., Xu, Z.Q., et al., 2005. Petrology and mineralogy of PP3 ultramafic rocks in Sulu UHP belt and its significance. Acta Petrologica Sinica, 21(2): 369-380 (in Chinese with English abstract). Cookenboo, H.O., Bustin, R.M., Wilks, K.R., 1997. Detrital chromium spinel compositions used to reconstruct the tectonic setting of provenance: Implications for orogeny in the Canadian Cordilera. Journal of Sedimentary Research, 67: 116-123. Dick, H.J.B., Bullen, T., 1984. Chromium spinel as a petrogenetic indicator in abyssal and Alpine-type peridotites and spatially associated lavas. Contribution to Mineralogy and Petrology, 86: 54-76. doi: 10.1007/BF00373711 Evans, B.W., Frost, B.R., 1975. Chrome-spinel in progressive metamorphism— A preliminary analysis. Geochimica et Cosmochimica Acta, 39: 957-972. Green, D.H., Ringwood, A.E., 1967. The stability fields for aluminous pyroxene peridotite and garnet peridotite and their relevance in upper mantle structure. Earth Planet. Sci. Letters, 3: 151-160. doi: 10.1016/0012-821X(67)90027-1 Guillot, S., Hattori, K.H., Sigoyer, J.D., et al., 2001. Evidence of hydration of the mantle wedge and its role in the exhumation of eclogites. Earth and Planetary Science Letters, 193: 115-127. doi: 10.1016/S0012-821X(01)00490-3 Irvine, T.N., 1965, Chrome spinel as a petrogenetic indicator. Part Ⅰ. Theory. Can. Jour. Earth Science, 2: 648-674. doi: 10.1139/e65-046 Ishii, T., 1987. Seamounts and oceanic islands: Their classification, vertical movements and histories. Earth Monthly, 9: 542-549(in Japanese). Kepezhinskas, P., McDermott, F., Defant, M. J., et al., 1997. Trace element and Sr-Nd-Pb isotopic constraints on a three-component model of Kamchatka arc petrogenesis. Geochim. Cosmochim. Acta, 61: 577-600. doi: 10.1016/S0016-7037(96)00349-3 Kepezhinskas, P.K., Defant, M.J., 1997. Progressive enrichment of island arc mantle by melt-peridotite interaction inferred from Kamchatka xenoliths. Geochim. Cosmochim. Acta, 60: 1217-1229. Klemme, S., 2004. The influence of Cr on the garnet-spinel transition in the Earth's mantle: Experiments in the system MgO-Cr2O3-SiO2and thermodynamic modelling. Lithos, 77(1-4): 639-646. doi: 10.1016/j.lithos.2004.03.017 Lee, Y.I., 1999. Geotectonic significance of detrital chromian spinel: A review. Geosciences Journal, 3(1): 23-29. doi: 10.1007/BF02910231 Nixon, P. H., 1987. Mantle xenoliths. Wiley, New York, 844. Ozawa, K., 1994. Melting and melt segregation in the mantle wedge above a subduction zone: Evidence from the chromite-bearing peridotites of the Miyamori ophiolite complex, northeastern Japan. J. Petrology, 35: 647-678. doi: 10.1093/petrology/35.3.647 O'Neill, H. St. C., 1981. The transition between spinel lherzolite and garnet lherzolite, and its use as a geobarometer. Contributions to Mineralogy and Petrology, 77: 185-194. doi: 10.1007/BF00636522 Pearce, J.A., Barker, P.F., Edwards, S.J., et al., 2000. Geochemistry and tectonic significance of peridotites from the South Sandwich arc-basin system, South Atlantic. Contrib. Mineral. Petrol. , 139: 36-53. doi: 10.1007/s004100050572 Press, S., 1986. Detrital spinels from alpinotype source rocks in Middle Devonian sediments of the Rhenish massif. Geologische Rundschau, 75: 333-340. doi: 10.1007/BF01820615 Roeder, P., 1974. The crystallization of spinel from basaltic liquid as a function of oxygen fugacity. J. Geol. , 82: 709-729. doi: 10.1086/628026 Roeder, P.L., 1994. Chromite: From the fiery rain of chondrules to the Kilauea Iki lava lake. Can. Mineral. , 32: 729-746. Roeder, P.L., Campbell, I.H., 1985. The effect of postcumulus reactions on composition of chrome-spinels from the Jimberlana intrusion. Journal of Petrology, 26(3): 763-786. doi: 10.1093/petrology/26.3.763 Widom, E., Kepezhinskas, P., Defant, M., 2003. The nature of metasomatism in the sub-arc mantle wedge: Evidence from Re-Os isotopes in Kamchatka peridotite xenoliths. Chemical Geology, 196: 283-306. doi: 10.1016/S0009-2541(02)00417-5 Wood, B.J., Virgo, D., 1989. Upper mantle oxidation state: Ferric iron contents of harzburgite spinels by 57Fe Mossbauer spectroscopy and resultant oxygen fugacities. Geochim. Cosmochim. Acta, 53: 1277-1291. doi: 10.1016/0016-7037(89)90062-8 Yang, J.S., Chen, S.Z., Zhang, Z.M., et al., 2005. A preliminary study of the Chinese Continental Scientific Drilling (CCSD)PP3 hole on the Gangshang garnet peridotite body in the Sulu UHPM belt. Acta Petrologica Sinica, 21(2): 293-304(in Chinese with English abstract). Yang, J.S., Xu, Z.Q., Pei, X.Z., et al., 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(4): 484-495. Yang, J.S., Xu, Z.Q., Song, S.G., et al., 2000. Discovery of eclogite in Dulan, Qinghai Province and its significance for the HP-UHP metamorphic belt along the central orogenic belt of China. Acta Geologica Sinica, 74: 156-168. 陈世忠, 杨经绥, 许志琴, 等, 2005. 大陆科学钻探CCSD-PP3钻孔超镁铁岩岩石学和矿物学特征及其意义. 岩石学报, 21(2): 369-380. https://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200502010.htm 杨经绥, 陈世忠, 张仲明, 等, 2005. 苏鲁超高压变质带岗上石榴石橄榄岩岩体: 中国大陆科学钻探卫星孔(CCSDPP3钻孔)初步研究. 岩石学报, 21(2): 293-304. https://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200502004.htm -
下载:
点击查看大图
计量
- 文章访问数: 3875
- HTML全文浏览量: 422
- PDF下载量: 7
- 被引次数: 0
