阿尔金山南缘长沙沟镁铁-超镁铁质层状杂岩体的发现与地质意义——岩石学和地球化学初步研究
Discovery of layered mafic-ultramafic intrusion in Changshagou, Altyn Tagh, and its geological implication: A pilot study on its petrological and geochemical characteristics
-
摘要: 阿尔金山南缘地区，侵入于新太古界—新元古界变质地层中的长沙沟镁铁-超镁铁质岩由四个呈断层接触的镁铁-超镁铁质岩块组成，形成年龄为462~470Ma。不同岩块内岩石的地球化学特征虽有差异，但均以LREE及强不相容元素的富集和高的Zr/Y比值（＞4.1）为特征，形成于大陆裂谷环境。其中，清水泉北段可以划分出3~4个主体由辉橄岩-角闪辉长岩构成的岩浆旋回，具有层状岩体的特征，其母岩浆的Mg#=53.7~55.9，为演化型母岩浆，暗示其经历了富镁矿物的分离结晶，且(Th/Nb)N＞1.0、Nb/La比值＜1.0、以及发育的矿物逆序包裹现象等表明经历了明显的地壳混染和岩浆混合作用；而清水泉南和长沙沟中段镁铁-超镁铁质岩的(Th/Nb)N＜1.0、Nb/La比值＞1.0，基本未遭受地壳混染，并且此Mg#与FeOT、TiO2负相关、与SiO2正相关，呈现良好的Fenner演化趋势特征；清水泉南纯橄岩-辉橄岩具有极高的Mg#（90.6~84.5），而赋存有钛-磁铁矿工业矿体的长沙沟中段镁铁-超镁铁岩的Mg#值较低（75.8~49.2），推测它们是同一母岩浆（Mg# =78.2）经Fenner演化趋势后分别形成的早期富Mg矿物堆晶相和稍晚期的富Fe-Ti残余岩浆相。长沙沟中奥陶世裂谷型层状镁铁-超镁铁质杂岩体的发现，意味着这一时期阿尔金山南缘地区处于伸展背景下，具有形成岩浆型PGE-Cu-Ni硫化物矿床和V-Ti-Fe氧化物矿床的地质背景和重要的成矿物质载体。作为该地区一种新的找矿思路，该地区同一构造带内其它镁铁-超镁超镁铁质岩体的性质及可能的金属矿化作用等也是值得进一步研究探索的。
-
关键词:
- 层状镁铁-超镁铁质岩 /
- 地球化学 /
- 地质意义 /
- 长沙沟 /
- 阿尔金山南缘
Abstract: The Changshagou layered intrusion are comprised of some mafic-ultramafic blocks with ages of 462~470 Ma, the Northern Qingshuiquan (NQ), Southern Qingshuiquan (SQ) and Middle section of Changshagou (MC), comparted by faults. They intruded in the Neoarchean and Neoproterozoic metamorphic strata on the southern margin of Altyn Tagh. The geochemical characteristics of the mafic-ultramafic rocks from these blocks are not uniform, but they all formed in continental rift tectonic setting according to the enrichments in LREEs and strong incompatible elements and higher Zr/Y ratios(＞4.1). The NQ mafic-ulmafic block consists of three to four magmatic cycles and exhibits the feature of layered mafic-ultramafic intrusion; higher (Th/Nb)N ratios (＞1.0), lower Nb/La ratios (＜1.0) and reverse mineral enwrapping of these rocks indicate the crust contamination and mingling of magma; lower Mg#（53.7~55.9）of their parental magma suggest they are from evolved magma undergone by significant fractional crystallization. Whereas the lower (Th/Nb)N ratios (＜1.0) and higher Nb/La ratios(＞1.0) of macfic-ultrmafic rocks from SQ and MC indicate they were not contaminated by crust. The increasing FeOT and TiO2, and decreasing SiO2 with decreasing Mg# of these macfic-ultrmafic rocks from SQ and MC present the distinct Fenner trend for magma evolution. Accordingly, we inferred that the mafic-ultramafic rocks with higher Mg# (90.6~84.5) from SQ were the magnesium-enriched cumulus phase from the parental (primary) magma with Mg#=78.2, while the mafic-ultramafic rocks with lower Mg#(75.8~49.2) from MC intrusion containing Ti-magnetite orebodies, were the residual magma phase by Fenner-trend of fractional crystallization from this parental magma. Occurrences of the Changshagou continental rift-type layered mafic-ultramafic intrusion indicate the south margin of Altyn Tagh were in the continental extending setting in middle Ordovician. As a new idea for geologic exploration in this area, the distribution and potential magmatic PGE-Cu-Ni sulfide and V-Ti-Fe oxide metallization of the same type intrusions in this area are worthy of further study.-
Key words:
- Layered mafic-ultramafic intrusion /
- Geochemistry /
- Geological implication /
- Changshagou /
- Altyn Tagh
-
-
[1] 广两地质调查院,1:25万瓦石峡幅(J45C002003)地质图及区域地质调查报告,2003.
[2] Brooks CK,Larsen LM,Nielsen TFD,Importance if iron-rich tholeiitic magma at divergent plate margins:A Reappraisal,Geology,1991.
[3] Colman RG,Ophiolites,Ancient ocean lithosphere?Minerals and Rocks,Beilin:Springer-Verlag,1977.
[4] Day JMD,Pearson DG,Hulbert LJ,Rhenium-osmium isotope and platinum-group element constrains on the origin and evolution of the 1,27 Ga Muskox layered intrusion,Journal of Petrology,2008(7).
[5] Dong XY,Li H,Ye LH,Li JM,Zheng JT,Wang YS,Yang XZ and Zhao DH,Ultramafic Rocks in China,北京:地质出版社,1995.
[6] Dong YP,Zhou DW,Zhang CL,Xia LQ Xu XY and Li XM,Tectonic setting of the Wuwamen ophiolite at the southern margin of Middle Tianshan Belt,Acta Petrolagica Sinica,2005(1).
[7] Herzberg C,Asimow PD,Arndt N,Niu Y,Lesher CM,Fitton JG,Cheadle MJ and Saunders AD,Temperatures in ambient mantle and plumes:Constraints from basalts,picrites,and komatiites,Geochemistry Geophysics and Geosystems,2007.
[8] Hertogen J,Emmermann R,Robinson PT,Erzinger J,Lithology,mineralogy,and geochemistry of the lower ocean crust,ODP Hole 735B,Southwest Indian Ridge,College station,TX:Ocean Drilling Program,2002.
[9] Hess PC,Phase equilibria constraints on the origin of ocean floor basalts,American Geophysical Union,1992.
[10] Lee CA,A review of mineralization in the Bushveld Complex and some other layered intrusions,Amsterdam:Elsevier Science,1996.
[11] 李金祥.秦克章.徐兴旺.孙赫.程松林.吴华.莫新华 新疆东天山白石泉Cu-Ni硫化物矿床杂岩体的地球化学特征及其对矿床成因和构造背景的制约 [J].-矿床地质2007(1)
[12] Li XM,Ma ZP,Sun JM,Xu XY Lei YX Wang LS and Duan XX,Characteristics and age study about the Yuemakeqi maficultramagfic rock in the southern Altyn Fault,Acta Petrologica Sinica,2009(4).
[13] Liu L,Che ZC,Wang Y,Luo JH Wang JQ and Gao JZ,The evidence of Sm-Nd isochron age for the Early Paleozoic ophiolite in Mang\'ai area,Altun Mountains,Chinese Science Bulletin,1998(8).
[14] Liu L,Zhang AD,Cben DL,Yang JX Luo JH and Wang C,Implications based on LA-ICP-MS Zircon U-Pb ages of eclogite and its country rock from Jianggalesayi area,Altyn Tagh,Earth Sciences Frontiers,2007(1).
[15] Liu L,Zhang JF,Green Ⅱ HW,Jin ZM and Bozhilov KN,Evidence of former stishovite in metamorphosed sediments,implying subduction to ＞ 350 km,Earth and Planetary Science Letters,2007.
[16] 毛景文.Franco PIRAJNO.张作衡.柴凤梅.杨建民.吴华.陈世平.程松林.张长青 天山-阿尔泰东部地区海西晚期后碰撞铜镍硫化物矿床:主要特点及可能与地幔柱的关系 [J].-地质学报2006(7)
[17] Naldrett AJ,Magmatic Sulfide Deposits,Geology,Geochemistry and Exploration,Berlin Heidelberg:Springer-Verlag,2004.
[18] 彭头平.王岳军.彭冰霞 一种罕见的岩石--富铁玄武岩/富铁苦橄岩研究进展 [J].-地球科学进展2005(5)
[19] Putirka KD,Perfit M,Ryerson FJ,Jackson MG,Ambient and excess mantle temperatures,olivine thermometry,andactive vs.passive upwelling,Chemical Geology,2007.
[20] Robinson PT,Dick HJB,Natland JH,Lower oceanic crust formed at ultraslow-spreading ridge:Ocean ODP Hole 735B,Southwest Indian Ridge,2000.
[21] Rooder PL,Emslie RF,Olivine-liquid equilibrium,Contibutions to Mineralogy and Petrology,1970.
[22] Saunders AD,Storey M,Kent RW,Norry MJ,Consequences of plume-lithosphere interaction,Geol.Soc.Spec.Pub.,London,1992.
[23] Sinton JM,Wilson DS,Christie DM,Hey RN and Delaney JR,Petrologic consequences of rift propagation on oceanic spreading ridges,Earth and Planetary Science Letters,1983.
[24] Sun SS,MeDonough WF,Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes,Geol.Soc.Spec.Pub.,London,1989.
[25] 唐冬梅.QIN KeZhang.刘秉光.孙赫.LI JinXiang 铂族元素矿床的主要类型、成矿作用及研究展望 [J].-岩石学报2008(3)
[26] Taylor SR,Mclennan SM,The Continental Crust:Its Composition and Evolution,Blackwell:Oxford,1985.
[27] Wang YW,Wang JB,Wang LJ,Peng XM Hui WD and Qin QX,A intermediate type of Cu-Ni sulfide and V-Ti magnetite deposit:Xiangshangxi deposit,Hami,Xinjiang,China,Acts Geologica Sinica,2006(1).
[28] Wang YW,Wang JB,Wang LJ,Compassion of host rocks between two vanadic titianomagnetite deposit types from the eastern Tianshan mountains,Acta Petrolagica sinica,2006(5).
[29] Wilson M,Igneous Petrogenesis,London:Unwin and Hyman,1989.
[30] Xia LQ,Xia ZC,Xu XY,Li XM,Ma ZP and Wang LS,The magmatism in Tianshan,Beijing:China-Land Press,2007.
[31] Xia LQ,Xia ZC,Xu XY,Li XM and Ma ZP,The discrimination between continental basalt and island arc basalt based on geochemical method,Acts Petrologica et Mineralogica,2007(1).
[32] Xu XW,Qin KZ,San JZ,Wang Y Hui WD Kang F Man J Li JX Sun H and Ma YG,Discovery of layered mafic-ultramafic intrusives formed in 545Ma in the Sidingheihan area,eastern Tianshan,China and its significances for tectonics and Cu-Ni mineralization,Acts Petrologica sinica,2006(11).
[33] ZHANG Anda.LIU Liang.SUN Yong.CHEN Danling.WANG Yan.LUO Jinhai SHRIMP U-Pb zircon ages for the UHP metamorphosed granitoid gneiss in Altyn Tagh and their geological signifi-cance [J].-科学通报(英文版)2004(23)
[34] Zhang JX,Mattinson CG,Meng FC,Wang YS,An Early Paleozoic HP/HT granulite garnet peridotite association in the South Altyn Tag,h,NW China:P-T history and U-Pb geochronology,Journal of Metamorphic Geology,2005.
[35] 张建新.张泽明.许志琴.崔军文.杨经绥 阿尔金西段孔兹岩系的发现及岩石学、同位素代学初步研究 [J].-中国科学D辑1999(4)
[36] Zhang Q,Zhou GQ,Ophiolites of China,北京:科学出版社,2001.
[37] Zhang Q,Li DZ,Zhang KW,Zhao DS,The characteristics of Yidun-type mafic-ultramafic rocks and their comparison with ophiolites,Acts Petrologica sinica,1990.
[38] Zhong H,Hu RZ,Zhu WG,Liu BG,Genesis and mineralization of layered intrusions,Earth Sciences Frontiers,2007(2).
[39] Zhou MF,Robinson PT,Lesher CF,Keays RR Zhang CJ and Malpas J,Geochemistry,petrogenesis and metallogenesis of the Panzhihua gubbroic layered introusion and associationed Fe-Ti-V oxide Deposits,Sichuan Province,SW China,Journal of Petrology,2005(11).
[40] 董显扬,李行,叶良和,李金铭,郑金田,王懿圣,扬轩柱,赵东宏,中国超镁铁质岩,北京:地质出版社,1995.
[41] 董云鹏.周鼎武.张国伟.张成立.夏林圻.徐学义.李向民 中天山南缘乌瓦门蛇绿岩形成构造环境 [J].-岩石学报2005(1)
[42] 李金祥.秦克章.徐兴旺.孙赫.程松林.吴华.莫新华 新疆东天山白石泉Cu-Ni硫化物矿床杂岩体的地球化学特征及其对矿床成因和构造背景的制约 [J].-矿床地质2007(1)
[43] 李向民,马中平,孙吉明,徐学义,雷永孝,王立社,段星星,阿尔金断裂南缘约马克其镁铁-超镁铁岩的性质和年代学研究,岩石学报,2009(4).
[44] 刘良,车自成,王焰,罗金海,王建其,高章鉴,阿尔金茫崖地区早古生代蛇绿岩的Sm-Nd等时线年龄证据,科学通报,1998(8).
[45] 刘良.张安达.陈丹玲.杨家喜.罗金海.王超 阿尔金江尕勒萨依榴辉岩和围岩锆石LA-ICP-MS微区原位定年及其地质意义 [J].-地学前缘2007(1)
[46] 毛景文.Franco PIRAJNO.张作衡.柴凤梅.杨建民.吴华.陈世平.程松林.张长青 天山-阿尔泰东部地区海西晚期后碰撞铜镍硫化物矿床:主要特点及可能与地幔柱的关系 [J].-地质学报2006(7)
[47] 彭头平.王岳军.彭冰霞 一种罕见的岩石--富铁玄武岩/富铁苦橄岩研究进展 [J].-地球科学进展2005(5)
[48] 唐冬梅,秦克章,刘秉光,李金祥,孙赫,铂族元素矿床的主要类型、富集规律、研究进展与展望,岩石学报,2008(3).
[49] 王玉往.王京彬.王莉娟.彭晓明.惠卫东.秦全新 岩浆铜镍矿与钒钛磁铁矿的过渡类型--新疆哈密香山西矿床 [J].-地质学报2006(1)
[50] 王玉往.王京彬.王莉娟 东天山地区两类钒钛磁铁矿型矿床含矿岩石对比 [J].-岩石学报2006(5)
[51] 夏林圻,夏祖春,徐学义,李向民,马中平,王立社,天山岩浆作用,北京:中国大地出版社,2007.
[52] 夏林圻.夏祖春.徐学义.李向民.马中平 利用地球化学方法判别大陆玄武岩和岛弧玄武岩 [J].-岩石矿物学杂志2007(1)
[53] 徐兴旺.秦克章.三金柱.王瑜.惠卫东.康峰.毛骞.李金祥.孙赫.马玉光 东天山四顶黑山地区545Ma层状镁铁质-超镁铁质岩体的发现及其大地构造学和成矿学意义 [J].-岩石学报2006(11)
[54] 张安达.刘良.孙勇.陈丹玲.王焰.罗金海 阿尔金超高压花岗质片麻岩中锆石SHRIMP U-Pb定年及其地质意义 [J].-科学通报2004(22)
[55] 张建新.张泽明.许志琴.崔军文.杨经绥 阿尔金西段孔兹岩系的发现及岩石学、同位素代学初步研究 [J].-中国科学D辑1999(4)
[56] 张旗.李达周.张魁武.赵大升 义敦型镁铁.超镁铁岩的主要特征及其与蛇绿岩的对比 [J].-岩石学报1990
[57] 张旗,周国庆,中国蛇绿岩,北京:科学出版社,2001.
[58] 钟宏.胡瑞忠.朱维光.刘秉光 层状岩体的成因及成矿作用 [J].-地学前缘2007(2)
-
计量
- 文章访问数: 9809
- PDF下载数: 6253
- 施引文献: 0
下载: