Hydrothermal Origin of Top Sinian Chert Formation at Gusui,Western Guangdong,China:Petrologic and Geochemical Evidence
-
摘要: 古水剖面震旦系顶部硅岩主要发育层状构造、纹理状构造、块状构造和假角砾状构造，化学成份以ＴｉＯ２、Ａｌ２Ｏ３和大部分微量元素亏损（相对地壳克拉克值）为特征。但Ｂａ、Ａｓ和Ｓｂ等少数已知的热水沉积特征元素显示富集。在Ａｌ－Ｆｅ－Ｍｎ三元图上，古水硅岩投映在“热水沉积”域内。因子分析和对应分析显示了大部分金属元素在代表热水淋滤作用的因子上均有反映。稀土元素以低含量为特征，在对北美页岩组合样（ＮＡＳＣ）正规化后的稀土配分模式落在典型热水沉积的上、下限之间，而在正常沉积的之外。各种岩性和地球化学证据表明，古水硅岩具有热水成因。Abstract: The Sinian ( Precambrian ) chert formation occurs at Gusui,western Guangdong Province,southern China,and is an integral part of the source strata of the Hetai gold field. The presence of the chert formation offers an excellent opportunity to evaluate the possible hydrothermal system and its role in the formation of the.source strata. The Precambrian chert from Gusui is characterized by bedded, laminated,massive and pseudobrecciated structures, and the depletion of TiO2,AI2O3and most trace elements. However, it is enriched in Ba,As, Sb, Hg and Se,which are considered as diagnostic elements of hydrothermal sediments. In the Al一Fe一Mn ternary diagram,it falls into the“hydrothermal field ". Correspondence analysis and factor analysis reveal that many elements show up in the factor that represents the leaching of country rocks by hydrothermal solution,and is the very characteristic element association of the geochemically anomalous South China basement. REE are characterized by a low total content and a gradually increasing NASC一normalized value with increasing atomic number of REE, ranging between the upper and the lower limits of typical hydrothermal deposits.The petrologic and geochemical evidences suggest a hydrothermal origin for the chert. It may have formed in a Precambrian rift or extension zone developed within the Yunkai marginal geosyncline.with a fault system linkihg to an unknown heat source at depth.
-
Key words:
- Precambrian /
- southern China /
- chert /
- petrologic evidence /
- geochemical evidence /
- multivariate analysis
-
[1] 陈础挺等.1988.广东地质.(1):1~16. [2] 广东省地质局.1977.1,200000地质图及说明书。 [3] 中国科学院地球化学研究所.1979.华南花岗岩的地球化学.科学出版社，北京.421. [4] 周永章，杨漪华.1988.矿物岩石地球化学通讯，(4);223~226. [5] 周永章.1990.沉积学报，(3);75~83, [6] Adaclti. M. et.1986.Sedimentary Geology. 47.125148. [7] Bastrom, K. and Peterson . M. N. A.。1969. Marine Qeology. 7. 427~447. [8] Gben.X. P. and Chcn.D. F.，1990. Chinese Journal of Geoe6emlstry. 9.46~53 [9] Crerar.D. A. et.，1982. Economic Geology.77.519!540. [10] Fleet.A. J.,1983.Hydrothermal Proor}re at Seaflorn Spreading Canters(edited by P.A. Rang et al. ).Plentun Pry. New Yotk, 535~556. [11] Fournia. R. O., 1985. ReviewsEconomic Geology. Volume 2. Society of Eomomic Geologlats, 45~82. [12] Hein.J. R. et al.，1983. SiLoeoua Deposits in.Padtic Regla}(edited by A. Iimetal.)，Elsevier. Amsterdam. 143~174. [13] Keith.T. E. C. and Mufller.L. J. P. . 1978. Journal of Volexrwlogy and Geothermal Research. 3. 373~402. [14] Kuijper. E. P. and Denyer. P.，1979. Eoottomk Geoktgy. T4. 672~678. [15] Lovering.T. G.，1972. U. S. Gaolagial Survey Profe}anal Paper 710. 164. [16] Maxchiy. V.，1982. Marine Geology. 50. 241~256. [17] Maynard.J. B.，1983.。Geochemjatry of Sedimentary Ore Deposits. SprLtger一Vetlag, New York. 305. [18] Moorby,S. A. and Ctonan, D. S.，1979. Initial Reports of Deep Sea Drlling.Project. Washington. D. C. . U. S. Govt.Print.Offiee, 70. 269~275. [19] Pollack.S. G.，1987, Journal of Sedimentary Petrology, 57. 7587. [20] Sugslakl. R.，1984. Journal of Geology. 92. 235~259. [21] White,D. E.，1981 .Economic Geology, 75th Anniversary Volume,392~423. [22] Yamamoto. K.，1987.Sedimentary Geology.52.65~108. [23] Zhou,Y. Z. et al.，1991. Program with Abatracts Volume 16. Geological Association of Canada. A138. [24] Zhou,Y。Z。1992, Geochemistry and Metallogenetic Mechanism of the Hetai Gold Fieid, Southern China. Ph. D Thesis Universitf du Quebec b Chieoutiml. 279. [25] Zhou.Y.Z.1993. Oeolagy and Geochemistry of the Hetai Gold Field, Southern China, Guangzhou; South China University of Technology Press. 310. -
点击查看大图
计量
- 文章访问数: 542
- HTML全文浏览量: 9
- PDF下载量: 472
- 被引次数: 0
下载:
