Isotopic Tracer of Material Origin for Hydrothermal Sedimentary Rocks and Significance in Xicheng Mineralization Area
-
摘要: 利用硅同位素、锶同位素和碳氧同位素,对西成矿化集中区与矿体紧密伴生的热水沉积岩的物质来源进行了探讨。硅质岩的硅同位素δ3 0 SiNBS -2 8=- 0.6‰～ - 0.1‰,硅主要来源于下伏沉积岩;热水沉积岩的锶同位素比值87Sr/ 86Sr变化于 0.70 938～ 0.72 812之间,位于海洋锶和陆壳锶之间,为混合锶,其锶主要来源于下伏沉积地层柱;碳同位素组成略低于正常沉积碳酸盐岩,碳主要来源于下伏沉积地层柱在循环碳,同时又受其它来源碳的影响。同位素研究结果表明,热水沉积岩的组成物质主要来源于下伏沉积地层柱 (地壳内部 ),形成方式主要是外生沉积作用,即热水沉积岩是内生作用与外生作用共同作用的结果,是内外生矛盾的统一体。Abstract: By means of silicon,strontium and carbon isotope, the material origin of hydrothermal sedimentary rocks associated closely with stratiform ore body is discussed in the paper. The value of silicon isotope δ 30 Si NBS-28 for silica rocks ranges from -0.6 ‰to -0.1‰, and it is consistent with the value of sedimentary rocks. The result of silicon isotope indicates that silicon of silica rocks comes mainly from sedimentary pile under Devonian. The value of 87 Sr/ 86 Sr for hydrothermal sedimentary rocks, such as silica rocks, chloritite, baritite and carbonate, changes from 0.709 38 to 0.728 12 and lie between ocean strontium and crust strontium. The composition of strontium of hydrothermal sedimentary rocks belongs to mixed strontium and origins from recycled strontium of underlying sedimentary pile. δ 13 C PDB and δ 18 O PDB of hydrothermal sedimentary carbonate ranges respectively from -2.7‰ to 4.3‰,-10.0 ‰to -2.0‰, and the value of δ 13 C PDB is close to natural carbonate, but δ 18 O PDB of hydrothermal sedimentary carbonate is depleted. The result of silicon and strontium indicates that the composition of hydrothermal sedimentary rocks comes mainly from sedimentary pile underlying Devonian, but its forming manner is exogenous, as well as we can say that the hydrothermal sedimentary rock is entia of endogenetic and exogenetic.
-
Key words:
- Xicheng mineralization area /
- hydrothermal sedimentary rocks /
- isotope /
- material source
-
[1] Bischoff J L.Red sea geothermal brine deposits:their mineralogy,chemistry and genesis[A].In:Degens E T,Ross D A,eds.Hot brine and recent heavy metal deposits in the Red sea[C].Springer,Berlin,Heidelberg,New York,1969.368～401 [2] Ridge J D.Volcanic exhalations and ore deposition in the vicinity of the seafloor[J].Min Deposit,1973,8(2):332～348 [3] 韩发,哈钦森 R W.大厂锡多金属矿床热液喷气沉积的证据-含矿建造及热液沉积岩[J].矿床地质,1989,8(2):25～37 [4] 薛春纪.沉积岩中海底热液沉积矿床岩石学[J].矿物岩石地球化学通讯,1990,(4):228～229 [5] 陈先沛,陈多福.广西上泥盆统乳房状燧石的热水沉积地球化学特征[J].地球化学,1989,(1):1～7 [6] 丁悌平等.硅同位素地球化学[M].北京:地质出版社,1994 [7] 孙省利,王国安,袁明坤.西成铅锌矿田铅、硫同位素特征及成矿物质来源的研究[J].甘肃地质学报,1992,1(2):51～65 [8] 尹观.同位素水文地球化学[M].成都:成都科技大学出版社,1988 [9] 郑荣才,刘文均.龙门山泥盆纪层序的碳、锶同位素效应.见:曾允孚等编著.中国古大陆和大陆边缘沉积学[C].成都:四川科学技术出版社,1996.475～483 [10] Al-Aasm I S,Blaise B.Interaction between hemipelagic sediment and a hydrothermal system:Middle Valley,northern Juan de Fuca Ridge,subarcic northeastpacific[J].Marine Geology,1991,98:25～38 [11] 杨振强.大宝山块状硫化物矿床成因:泥盆纪海底热事件[J].华南地质与矿产,1997,(1):7～17 [12] 蒙义峰,崔彬,杨军臣,张连昌.滇东南芦柴冲大型银多金属矿床的海底喷流成矿作用沉积旋回划分[J].地质与勘探,1998,34(3):16～20 [13] 王集磊,何伯墀,李健中,何典仁.中国秦岭型铅锌矿[J].北京:地质出版社,1996 [14] Craig H.Isotopic composition and origin of the Red sea and Salton sea geothermal brines[J].Science,1966,1541～1544 [15] 武安斌,宋春晖,孙省利.甘肃省西成矿田中泥盆统沉积相古地理与控矿作用[M].兰州:兰州大学出版社,1992 [16] 田景春,曾允孚.中国南方二叠纪古海洋锶同位素演化[J].沉积学报,1995,13(4):125～130 [17] Spooner E.The strontium isotope composition of sea water and seawater-oceanic crust interaction[J].Earth Plant.Sci.Lett.1996,13:167～174 -
点击查看大图
计量
- 文章访问数: 561
- HTML全文浏览量: 27
- PDF下载量: 302
- 被引次数: 0
下载:
