安徽栏杆含金刚石基性岩中辉石及钛铁矿矿物化学特征
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摘要
在中国东部皖北地区分布着新元古代镁铁质岩,岩石类型为辉绿岩、辉绿辉长岩、辉绿玢岩等。其中主要组成矿物为辉石、斜长石、角闪石、铁钛氧化物等。利用电子探针对单斜辉石和钛铁矿进行了详细研究。单斜辉石分析表明,其端元分子组成硅灰石分子(Wo)为33.27～43.04,顽火辉石分子(En)为38.79～46.63,斜方铁辉石(Fs)为10.45～24.83,属于普通透辉石。计算结果及化学成分比值说明,单斜辉石应该是在寄主碱性玄武质岩浆晚期低压下结晶的,可能是碱性玄武质岩浆浅位岩浆房晶出的产物。单斜辉石的结晶温度为1109～1206℃,压力最高为0.6GPa,相当于深部19.8km。栏杆地区钛铁矿含MgO和Cr_2O_3较低,具有富FeO,并含少量MnO的特点,属于含镁锰钛铁矿。两类矿物特征均与典型金伯利岩中的指示矿物不同。
Mafic rocks are exposed in northern Anhui Province. It consists of diabase, gabbro-diabase and diabase-porphyrite, and the minerals mainly include clinopyroxene, plagioclase, hornblende and Ti-Fe oxides. In this paper, clinopyroxene and ilmenite were studied in detail using microprobe. An analysis of clinopyroxenes shows that the end members are composed of wollastonite, enstatite and ferrosilite, belonging to augite. Calculation results and chemical analysis of ratios probably indicate that the fractional crystallizing products were formed by the relatively primary magma in shallower magma chambers. The crystallizing temperature of theclinopyroxenes are 1109～1206℃ and the highest pressure is 0.6GPa,suggesting the depth of 19.8km. The ilmenite in Lan'gan area has low MgO and MnO, high FeO, and very low Cr_2O_3. The mineral characteristics of clinopyroxen and ilmenite are different from features of the index minerals in typical kimberlite.
Mafic rocks are exposed in northern Anhui Province. It consists of diabase, gabbro-diabase and diabase-porphyrite, and the minerals mainly include clinopyroxene, plagioclase, hornblende and Ti-Fe oxides. In this paper, clinopyroxene and ilmenite were studied in detail using microprobe. An analysis of clinopyroxenes shows that the end members are composed of wollastonite, enstatite and ferrosilite, belonging to augite. Calculation results and chemical analysis of ratios probably indicate that the fractional crystallizing products were formed by the relatively primary magma in shallower magma chambers. The crystallizing temperature of theclinopyroxenes are 1109～1206℃ and the highest pressure is 0.6GPa,suggesting the depth of 19.8km. The ilmenite in Lan'gan area has low MgO and MnO, high FeO, and very low Cr_2O_3. The mineral characteristics of clinopyroxen and ilmenite are different from features of the index minerals in typical kimberlite.
引文
[1]张洁,吕凤军,蔡逸涛.安徽栏杆碱性基性岩型金刚石矿遥感影像特征[J].宝石和宝石学杂志,2016,19(4):1-9.
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[5]孙主,莫默,丘志力,等.俄罗斯的金刚石及其产业发展[J].宝石和宝石学杂志,2012,14(1):14-23.
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[9]Kopecky L.Diamond prospects in the Czech massif[J].Izvest.Akad.Nauk SSSR,Ser.Geology,1960,12:46-55.
[10]黄先觉.金刚石原生矿床类型及安徽省金刚石找矿前景分析[J]安徽地质,2012,22(2):103-105.
[11]张岳桥,董树文.郯庐断裂带中生代构造演化史:进展与新认识[J].地质通报,2008,27(9):1371-1390.
[12]侯明金,王永敏,Mercier Jacques,等.郯庐断裂带(安徽部分)动力学演化及其构造意义[J].地质通报,2003,22(2):36-43.
[13]姚仲伯.安徽省区域地质概要[J].中国区域地质,1986,(4):309-312.
[14]徐向珍.新疆和田西北部金刚石成矿地质条件分析[D].中国地质大学(北京)硕士学位论文,2006.
[15]董振信.中国金伯利岩中的钛铁矿[J].矿物学报,1991,11(2):141-147.
[16]Mitchell R H,Bergman S C.Petrology of lamproites[M].New York:Plenum Press,1991.
[17]Morimoto N.Nomenclature of Pyroxenes[J].Mineralogy and Petrology,1988,39:55-76.
[18]董振信.中国金伯利岩中的单斜辉石[J].地质学报,1992,66(1):35-47.
[19]Dawson J B.Kimberlites and their xenoliths[M].New York:Springer Verlag,1980:100-104.
[20]邱家骧,曾广策.中国东部新生代玄武岩中低压单斜辉石的矿物化学及其岩石学意义[J].岩石学报,1987,(4):1-9.
[21]Kushiro I.Si-Al relation in clinopyroxenes from igneous rocks[J].American Journal of Science,1960,258:548-554.
[22]池际尚,路凤香,赵磊.华北地台金伯利岩及古生代岩石圈地幔特征[M].北京:科学出版社,1996.
[23]张安棣,谢锡林,郭立鹤.金刚石找矿指示矿物研究及数据库[M].北京:科学技术出版社,1991.
[24]Wass S Y.Mutiple origine of clinopyroxenes in alkali basaltic rocks[J].Lithos,1979,12:115-132.
[25]Kinzler R J.Melting of mantle peridotite at pressures approaching the spinel to garnet transition:Application to mid-ocean ridge basalt petrogenesis[J].Journal of Geophysical Research,1997,102(B1):853-874.
[26]肖燕,张宏福,范蔚茗.华北晚中生代和新生代玄武岩中单斜辉石巨晶来源及其对寄主岩岩浆过程的制约:以莒南和鹤壁为例[J].岩石学报,2008,24(1):65-76.
[27]张洁,蔡逸涛,董钟斗,等.安徽栏杆金刚石矿物特征及其寄主母岩地球化学特征研究[J].宝石和宝石学杂志,2015,17(5):1-11.
[28]Thompson R N.Some high-pressure pyroxenes[J].Minerological Magazine,1974,39:768-787.
[29]Putirka K D,Mikaelian H,Ryerson F,et al.New clinopyroxene-liquid thermobarometers for mafic,evolved,and volatile-bearing lava compositions,with applications to lavas from Tibet and the Snake River Plain,Idaho[J].American Mineralogist,2003,88(10):1542-1554.
[30]Mckenzie D,Bickle M J.The volume and composition of melt generated by extension of the lithosphere[J].Journal of Petrology,1988,29(3):625-679.
[2]蔡逸涛,陈国光,张洁,等.安徽栏杆地区橄榄辉长岩地球化学特征及其与金刚石成矿的关系[J].资源调查与环境,2014,35(4)245-253.
[3]蔡逸涛,杨献忠,康丛轩.国内外金刚石成因认识现状[J].华东地质,2017,38(Supp):95-102.
[4]张培元.积极探索突破新类型金刚石原生矿床[J].地质科技管理1998,15(5):1-8.
[5]孙主,莫默,丘志力,等.俄罗斯的金刚石及其产业发展[J].宝石和宝石学杂志,2012,14(1):14-23.
[6]Sobolev N V,Taylor L A,Zuev V M,et al.The specific features of eclogitic paragenesis of diamonds from Mir and Udachnaya kimberlite pipes(Yakutia)[J].Geologiya I Geofizika,1998,39(12)1667-1678.
[7]Spetsius Z V.Occurrence of diamond in the mantle:a case study from the Siberian Platform[J].Journal of Geochemical Exploration,1995,53(3):25-39.
[8]王仲会.金刚石成矿模型与勘查方法[M].北京:地质出版社1998.
[9]Kopecky L.Diamond prospects in the Czech massif[J].Izvest.Akad.Nauk SSSR,Ser.Geology,1960,12:46-55.
[10]黄先觉.金刚石原生矿床类型及安徽省金刚石找矿前景分析[J]安徽地质,2012,22(2):103-105.
[11]张岳桥,董树文.郯庐断裂带中生代构造演化史:进展与新认识[J].地质通报,2008,27(9):1371-1390.
[12]侯明金,王永敏,Mercier Jacques,等.郯庐断裂带(安徽部分)动力学演化及其构造意义[J].地质通报,2003,22(2):36-43.
[13]姚仲伯.安徽省区域地质概要[J].中国区域地质,1986,(4):309-312.
[14]徐向珍.新疆和田西北部金刚石成矿地质条件分析[D].中国地质大学(北京)硕士学位论文,2006.
[15]董振信.中国金伯利岩中的钛铁矿[J].矿物学报,1991,11(2):141-147.
[16]Mitchell R H,Bergman S C.Petrology of lamproites[M].New York:Plenum Press,1991.
[17]Morimoto N.Nomenclature of Pyroxenes[J].Mineralogy and Petrology,1988,39:55-76.
[18]董振信.中国金伯利岩中的单斜辉石[J].地质学报,1992,66(1):35-47.
[19]Dawson J B.Kimberlites and their xenoliths[M].New York:Springer Verlag,1980:100-104.
[20]邱家骧,曾广策.中国东部新生代玄武岩中低压单斜辉石的矿物化学及其岩石学意义[J].岩石学报,1987,(4):1-9.
[21]Kushiro I.Si-Al relation in clinopyroxenes from igneous rocks[J].American Journal of Science,1960,258:548-554.
[22]池际尚,路凤香,赵磊.华北地台金伯利岩及古生代岩石圈地幔特征[M].北京:科学出版社,1996.
[23]张安棣,谢锡林,郭立鹤.金刚石找矿指示矿物研究及数据库[M].北京:科学技术出版社,1991.
[24]Wass S Y.Mutiple origine of clinopyroxenes in alkali basaltic rocks[J].Lithos,1979,12:115-132.
[25]Kinzler R J.Melting of mantle peridotite at pressures approaching the spinel to garnet transition:Application to mid-ocean ridge basalt petrogenesis[J].Journal of Geophysical Research,1997,102(B1):853-874.
[26]肖燕,张宏福,范蔚茗.华北晚中生代和新生代玄武岩中单斜辉石巨晶来源及其对寄主岩岩浆过程的制约:以莒南和鹤壁为例[J].岩石学报,2008,24(1):65-76.
[27]张洁,蔡逸涛,董钟斗,等.安徽栏杆金刚石矿物特征及其寄主母岩地球化学特征研究[J].宝石和宝石学杂志,2015,17(5):1-11.
[28]Thompson R N.Some high-pressure pyroxenes[J].Minerological Magazine,1974,39:768-787.
[29]Putirka K D,Mikaelian H,Ryerson F,et al.New clinopyroxene-liquid thermobarometers for mafic,evolved,and volatile-bearing lava compositions,with applications to lavas from Tibet and the Snake River Plain,Idaho[J].American Mineralogist,2003,88(10):1542-1554.
[30]Mckenzie D,Bickle M J.The volume and composition of melt generated by extension of the lithosphere[J].Journal of Petrology,1988,29(3):625-679.
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