云南曲靖盆地蔡家冲粗面英安质凝灰岩——扬子克拉通内曲靖深断裂新生代强烈活动的证据
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摘要
云南曲靖盆地内的蔡家冲火山岩作为扬子克拉通内部深断裂受青藏高原向东南逃逸而影响强度的标志之一,具有重要意义。在该区新发现的新生代火山岩的斑晶成分主要为正长石和少量黑云母,为钾质火山岩(粗面质火山岩);结合火山岩的全岩成分、微量元素分析,确定蔡家冲火山岩为粗面质火山岩(超钾质火山岩),经湖相水解后K、Na等碱质组分部分流失,导致该区火山岩在火山岩分类图解中落入碱质稍低的花岗闪长岩区域,其本质是水解的粗面质火山岩;全岩K/Ar同位素测年显示:火山岩活动时间范围在44.9±0.8~48.4±0.9Ma之间;火山岩下部至上部年龄差大致为3.5Ma,属于古近纪始新世路特阶的产物。该区的新生代火山岩反映出,曲靖深断裂的走滑拉分不仅形成了曲靖、陆良、弥勒、开远等一系列盆地,其活动强度还导致新生代始新世路特阶的蔡家冲组火山岩的喷发,曲靖深断裂同小江深断裂一样,新生代活动显示为超壳深断裂。火山岩显著富集Cd、Pb、Zn等元素,综合考虑东川播卡等地深部发现同时期的富碱侵入岩及金矿床,该区火山岩显示的金矿、铅锌矿的找矿潜力值得关注。曲靖深断裂还与地震活动、热水资源、农业生态环境、油气资源、固体矿产等密切相关,值得深入研究。
As a symbol of the influence extent of the deep faults within the Yangtze Craton by the southeastward escape of the Tibetan Plateau, the volcanic rocks in the Qujing basin are of great research importance. By field observing and sampling, the Cenozoic volcanic rocks were found for the first time in this area. it is confirmed under the microscope that the volcanic rocks are trachytic(ultrapotassic) dacitic tuffs with phenocrystals of orthoclase and biotite, and K and Na of the volcanic rocks may be partly leached by hydrolysis, leading to the falling of volcanic rocks in the region of granodiorite on the volcanic rock classification diagram, as also shown by major and trace elements data. K/Ar dating result shows that the volcanic rock activity lasted for about 3.5Ma, i.e., from44.93±0.8Ma to 48.39±0.9Ma, suggesting the products of the Cenozoic Middle Eocene(Lutetian, 48.6±0.2~40.4±0.2Ma) volcanic activities. The volcanic rocks in Qujing basin show that the pull-apart of the Qujing deep fault not only formed a series of basinssuch as Qujing, Luliang, Mile and Kaiyuan, but also brought about the extrusion of the Cenozoic Eocene Lutetian Caijiachong Formation(E2c) volcanic rocks, which implies a strong activity of the Qujing deep fault; like the Xiaojiang deep fault which was responsible for the intrusion in Boka, Dongchuan, the Qujing deep fault was an utracrustal fault during Cenozoic. The volcanic rocks are significantly rich in such elements as Cd, Pb and Zn, indicating that the potentials of Au, Pb-Zn deposits related to the volcanic rocks are worthy of attention. In combination with the finding of the homochromous alkaline intrusion and gold deposits in Boka of the Dongchuan deep fault, the Qujing deep fault, which is closely related to the seismic activities, hot spring resources, agricultural and ecological environment, oil-gas resources, and solid minerals, deserves thorough investigation.
As a symbol of the influence extent of the deep faults within the Yangtze Craton by the southeastward escape of the Tibetan Plateau, the volcanic rocks in the Qujing basin are of great research importance. By field observing and sampling, the Cenozoic volcanic rocks were found for the first time in this area. it is confirmed under the microscope that the volcanic rocks are trachytic(ultrapotassic) dacitic tuffs with phenocrystals of orthoclase and biotite, and K and Na of the volcanic rocks may be partly leached by hydrolysis, leading to the falling of volcanic rocks in the region of granodiorite on the volcanic rock classification diagram, as also shown by major and trace elements data. K/Ar dating result shows that the volcanic rock activity lasted for about 3.5Ma, i.e., from44.93±0.8Ma to 48.39±0.9Ma, suggesting the products of the Cenozoic Middle Eocene(Lutetian, 48.6±0.2~40.4±0.2Ma) volcanic activities. The volcanic rocks in Qujing basin show that the pull-apart of the Qujing deep fault not only formed a series of basinssuch as Qujing, Luliang, Mile and Kaiyuan, but also brought about the extrusion of the Cenozoic Eocene Lutetian Caijiachong Formation(E2c) volcanic rocks, which implies a strong activity of the Qujing deep fault; like the Xiaojiang deep fault which was responsible for the intrusion in Boka, Dongchuan, the Qujing deep fault was an utracrustal fault during Cenozoic. The volcanic rocks are significantly rich in such elements as Cd, Pb and Zn, indicating that the potentials of Au, Pb-Zn deposits related to the volcanic rocks are worthy of attention. In combination with the finding of the homochromous alkaline intrusion and gold deposits in Boka of the Dongchuan deep fault, the Qujing deep fault, which is closely related to the seismic activities, hot spring resources, agricultural and ecological environment, oil-gas resources, and solid minerals, deserves thorough investigation.
引文
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[21]李大明,陈文寄,李齐.年轻火山岩的K-Ar年龄与过剩氩:二元混合模式及过剩氩的定量研究[J].科学通报,1999,44(21):2341-2345.
[22]谢应雯,张玉泉.青藏高原东部及邻区富碱侵入岩中的角闪石和辉石[J].矿物学报,1998,28(1):90-96.
[23]张玉泉,谢应雯.哀牢山-金沙江富碱侵入岩年代学和Nd,Sr同位素特征[J].中国科学(D辑),1997,27(4):289-293.
[24]Hou Z Q,Zeng P S,Gao Y F,et al.Himalayan Cu-Mo-Au Mineralization in the eastern Indo-Asian Collision Zone:Constraints from Re-Os Dating of molybdenite[J].Mineralium Deposita,2006,41(1):33-45.
[25]莫宣学,路风香,沈上越,等.三江特提斯火山作用与成矿[M].北京:地质出版社,1993.
[26]Schmid R.Descriptive nomenclature and classification of pyroclastic deposits and fragments.Recommendation of the IUGS subcommission on the Systematic of Igneous Rocks[J].Geology,1981,9:41-43.
[27]李兆鼐.火山碎屑岩的分类和命名[J].岩石矿物及测试,1984,4:301-309.
[28]曾普胜,侯增谦,高永峰,等.印度-亚洲碰撞带东段喜马拉雅期铜-钼-金矿床Re-Os年龄及成矿作用[J].地质论评,2006,52(1):72-84.
[29]曾普胜,莫宣学,喻学惠.滇西富碱斑岩的Pb、Sr、Nd同位素特征及其剪切挤压构造背景[J].岩石矿物学杂志,2002,21(3):231-241.
[30]Flower M F J,Tamiki K,Hoang N.Mantle extrusion:a model for dispersed volcanism and DUAPAL-like asthenosphere in East Asia and the western Pacific[C]//Flower.Mantle plume and plate interactions in East Asia.Geodyn.Series 27,AGU,Washington,1998:67-88.
1云南省地质局第二区测队.1∶20万曲靖幅区域地质调查报告.1980.
2 云南省地质局第二区测队.1∶20万宜良幅区域地质调查报告.1974.
[2]Tapponnier P,Lacassin R,Leloup P H,et al.The Ailao Shan-Red River metamorphic belt:Tertiary left-lateral shear between Indochina and South China[J].Nature,1990,343:431-437.
[3]唐文清,刘宇平,陈智梁,等.云南小江断裂中南段现今活动特征[J].沉积与特提斯地质,2006,2:21-24.
[4]钱晓东,秦嘉政.小江断裂带及周边地区强震危险性分析[J].地震研究,2008,4:354-361.
[5]李卿.云南曲靖盆地储层地震预测[D].成都理工大学硕士学位论文,2010.
[6]张翼飞.云南东川地区含金剪切带型金矿[J].云南地质,2003,4:360-370.
[7]李志伟,田敏,刘和林,等.东川拖布卡金矿地质及成矿年代学[J].云南地质,2003,4:371-381
[8]李志伟,钱祥贵,田敏.东川拖布卡—布卡地区金矿地质特征及找矿意义[J].大地构造与成矿学,2000,S1:37-43.
[9]应汉龙,刘和林,李志伟.云南东川播卡—拖布卡地区含金石英脉的40Ar/39Ar年龄及其地质意义[J].地质论评,2004,2:196-202.
[10]程辉明.云南播卡式金矿矿床地质特征及找矿前景分析[D].昆明理工大学硕士学位论文,2005.
[11]张学诚,高俊彩.昆明市东川拖布卡金矿矿石岩石学研究[J].云南地质,2006,3:276-285.
[12]王宝禄,李丽辉,曾普胜.川滇黔菱形地块地球物理基本特征及其与内生成矿作用的关系[J].东华理工学院学报,2004,27(4):301-308.
[13]朱炎铭.云南羊街盆地的走滑成因及构造反转.煤田地质与勘探[J].1996,3:8-11.
[14]滕德贞.云南的温泉和地震[J].地震研究,1982,1:23-29.
[15]Winchester J A,Floyd P A.Geochemical discrimination of differnent magma series and their differentiation products using immobile elements[J].Chemical Geology,1977,20:325-343.
[16]Peccerillo R,Taylor S R.Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area,Northern Turkey[J].Contrib.Mineral.Petrol.,1976,58:63-81.
[17]Le Maitre R W,Bateman P,Dudek A,et al.A Classification of Igneous Rocks and Glossary of Terms:Recommendations of the International Union of Geological Sciences Subcommission on the Systematics of Igneous Rocks[M].Oxford:Blackwell Scientific,1989.
[18]鄢明才,迟清华,顾铁新,等.中国东部上地壳化学组成[J].中国科学(D辑),1997,3:193-199.
[19]Sun S S,Mc Donough W F.Chemical and isotope systematics of oceanic basalts:Implications for mantle composition and processes[C]//Saunders A D,Norry M J.Magmatism in Ocean Basins.Geol.Soc.,London,Publication,1989,42:313-345.
[20]Boynton W V.Cosmochemistry of the rare earth elements:meteorite studies[C]//Henderson P.Rare earth element geochemistry.Elsevier,Amsterdam,1984:63-114.
[21]李大明,陈文寄,李齐.年轻火山岩的K-Ar年龄与过剩氩:二元混合模式及过剩氩的定量研究[J].科学通报,1999,44(21):2341-2345.
[22]谢应雯,张玉泉.青藏高原东部及邻区富碱侵入岩中的角闪石和辉石[J].矿物学报,1998,28(1):90-96.
[23]张玉泉,谢应雯.哀牢山-金沙江富碱侵入岩年代学和Nd,Sr同位素特征[J].中国科学(D辑),1997,27(4):289-293.
[24]Hou Z Q,Zeng P S,Gao Y F,et al.Himalayan Cu-Mo-Au Mineralization in the eastern Indo-Asian Collision Zone:Constraints from Re-Os Dating of molybdenite[J].Mineralium Deposita,2006,41(1):33-45.
[25]莫宣学,路风香,沈上越,等.三江特提斯火山作用与成矿[M].北京:地质出版社,1993.
[26]Schmid R.Descriptive nomenclature and classification of pyroclastic deposits and fragments.Recommendation of the IUGS subcommission on the Systematic of Igneous Rocks[J].Geology,1981,9:41-43.
[27]李兆鼐.火山碎屑岩的分类和命名[J].岩石矿物及测试,1984,4:301-309.
[28]曾普胜,侯增谦,高永峰,等.印度-亚洲碰撞带东段喜马拉雅期铜-钼-金矿床Re-Os年龄及成矿作用[J].地质论评,2006,52(1):72-84.
[29]曾普胜,莫宣学,喻学惠.滇西富碱斑岩的Pb、Sr、Nd同位素特征及其剪切挤压构造背景[J].岩石矿物学杂志,2002,21(3):231-241.
[30]Flower M F J,Tamiki K,Hoang N.Mantle extrusion:a model for dispersed volcanism and DUAPAL-like asthenosphere in East Asia and the western Pacific[C]//Flower.Mantle plume and plate interactions in East Asia.Geodyn.Series 27,AGU,Washington,1998:67-88.
1云南省地质局第二区测队.1∶20万曲靖幅区域地质调查报告.1980.
2 云南省地质局第二区测队.1∶20万宜良幅区域地质调查报告.1974.