辽西豆荚状铬铁矿的发现及其意义
The discovery of podiform chromite in west Liaoning and its implication for plate tectonics
-
摘要: 在辽西建平新太古代变质基底构造混杂带内首次识别出豆荚状铬铁矿。铬铁矿石显示特征的豆荚状构造、褶皱条带、透镜构造、豆状构造、拉长网孔构造等，它们可以与蛇绿岩内典型的豆荚状铬铁矿进行对比。依据同位素年龄制约，辽西豆英状铬铁矿形成于2．50Ga前后。结合该区已报道的新太古变基性火山岩具有大洋拉斑玄武岩成分特点、并广泛发育新太古代高压麻粒岩，可以认为辽西地区新太古代期间曾发生大规模的板块俯冲及碰撞作用过程。Abstract: The podiform chromite is identified associated with ultramafic blocks within a structural zone , which cut across a Neoarchean metamorphic terrain, west Liaoning. The characteristic structures of podiform chromite are shown by chromite deposits, such as structural layering, rootless folds, lenses, nodular structures, and antinodular structures etc. The geological occurrence and structures of the chromite ores are evidently comparable to the typical podiform chromites of ophiolites. As constrained by relevant isotopic age dating, the podiform chromite was generated about 2. 50Ga. Furthermore, the Neoarchean metamorphic mafic rocks of this area are chemically similar to MORB, and Neoarchean high-pressures are widely reported along the structural belt. It is suggested that the plate subduction and collision were regionally operated in the Neoarchean.
-
Key words:
- Podiform chromite /
- Nodular structure /
- Ultramafic blocks /
- Structural zone /
- Plate tectonics /
-
-
[1] ［1］Ahmed A H, Arai S and Attia A K. 2001. Petrological characteristics of podiform chromitites and associated peridotites of the Pan African Proterozoic ophiolite complexes of Egypt. Mineralium Deposita, 36:72-84
[2] ［2］Arai S and Matsukage K. 1998. Petrology of a chromitite micropod from Hess Deep, equatorial Pacific: a comparision between abyssal and alpine-type podiform chromitite. Lithos, 43:1-14
[3] ［3］Bao P S, Wang X B, Peng G Y, Chen F Y. 1999. Chromite Deposits in China. Beijing: Science Press, 98-142 (in Chinese with English abstract)
[4] ［4］Ballhaus C. 1998. Origin of podiform chromite deposits by magma mingling. Earth and Planetary Science Letters, 156:185-193
[5] ［5］Ji JQ and Chen MY. 1996. Genesis and significance of the myrmekitic symplectite from the Jianping metamorphic complex, western Liaoning. Acta Petrologica Sinica, 12(4):514-529 (in Chinese with English abstract)
[6] ［6］Kroner A, Cui W Y, Wang S Q, Wang C Q and Nemchin A A. 1998. Single zircon ages from high-grade rocks of the Jianping complex, Liaoning province, NE China. Journal of Asia Earth Sciences, 16:519-532
[7] ［7］Kusky T, Li J H and Tucker B. 2001. The Archean Dongwanzi ophiolite complex, North China Carton: 2. 505-billion -year-old oceanic crust and mantle. Science, 292:1142-1145
[8] ［8］Lin B Q, Cui W Y, Wang S Q and Shen E S. 1997. The Archean Geology and Gold Mineralism in West Liaoning. Beijing: Seismological Press, 1-43 (in Chinese with English abstract)
[9] ［9］Li J H, Qian X L, Huang X N and Liu S W. 2000. The tectonic framework of the basement of North China Craton and its implication for the early Precambrain cratonization. Acta Petrologica Sinica, 16(1):1-10 (in Chinese with English abstract)
[10] ［10］Lago B L, Rabinowicz M and Nicolas A. 1982. Podiform chromitite ore bodies: a genetic model. J. Petrol., 23:103-125
[11] ［11］Leblanc M and Nicolas A. 1992. Ophiolitic chromitites. International Geological Review, 34:653-686
[12] ［12］Leblanc M. 1997. Chromitite and ultramafic rock composional zoning through a paleotransform fault, Poum, New Caledonia - A reply. Economic Geology, 92:503-504
[13] ［13］Melcher T, Crum W, Simon G, Thalhammer T V, and Stumpfl E F. 1997. Petrogenesis of the ophiolitic giant chromite deposits of Kempirsai, Kazakhstan: a study of solid and fluid inclusions in chromite. Journal of Petrology, 38(10):1419-1458
[14] ［14］Moreno T, Gibbons W, Prichard H M and Lunar R. 2001. Platiniferous chromitite and the tectonics setting of ultramafic rocks in Cabo Ortegal, NW Spain. Journal of the Geological Society, London, 158:601-614
[15] ［15］Nicolas A. 1989. Structures of ophiolites and dynamics of oceanic lithosphere. Kluwer Academic Publishers, 223-252
[16] ［16］Nicolas A and Azri H A. 1991. Chromite-rich and chromite-poor ophiolites: the Oman case. In: Peter T et al. (Eds.), Ophiolite Genesis and Evolution of the Oceanic Lithosphere, 261-274
[17] ［17］Proenza J, Gervilla F, Melgarejo J C and Bodinier J L. 1999. Al-and Cr-rich chromitites from the Mayari-Baracoa ophiolitic belt(Eastern Cuba): consequence of interaction between volatile-rich melts and peridotites in suprasubduction mantle. Economic Geology, 94:547-566
[18] ［18］Thayer T P. 1969. gravity differentiation and magmatic re-emplacement of podiform chromite deposits. In: Magmatic Ore Deposits: Econ. Geo. Monograph, No. 4, 132-146
[19] ［19］Tamayo R A, Yumul G P, Maury R C, Polve M, Cotton J and Bohn M. 2001. Petrochemical investigation of the antique ophiolite(Philippines):implications on volcanogenic massive sulfide and podiform chromitite deposits. Resource Geology, 51(2):145-164
[20] ［20］Vuollo J, Liipo J, Nykanen V, Piirainen T. 1995. An early Proterozoic podiform chromitite in the Outokumpu ophiolite complex, Finland. Economic Geology, 90:445-452
[21] ［21］Wang K Y, Li J L, Hao J. 1997. Late Archean mafic-ultramafic rocks from the Wutaishan, Shanxi Province: a possible ophiolite melange. Acta Petrologica Sinica, 13(2):139-151 (in Chinese with English abstract)
[22] ［22］Yumul G P. 2001. The Acoje block platiniferous dunite horizon, Zambales ophiolite complex, Philippines:melt type and associated geochemical controls. Resource Geology, 51(2):165-174
[23] ［23］Zhang Q and Xiao X. 1995. A review of ophiolite in China. Acta Petrologica Sinica, 11(supp.):1-9 (in Chinese with English abstract)
[24] ［24］Zhou M F, Robinson P T, Malpas J, Li Z J. 1996. Podiform chromitites in the Luobusa ophiolite(South Tibet):implications for melt-rock interaction and chromite segregation in the upper mantle. Journal of Petrology, 37:3-21
[25] ［25］Zhou M F and Robinson P L. 1997. Origin and tectonic environment of podiform chromite deposits. Economic Geology, 92:259-262
-
计量
- 文章访问数: 6242
- PDF下载数: 7020
- 施引文献: 0
下载: