鄂尔多斯盆地东南部延长组长7段厚层熔结凝灰岩特征及其地质意义
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摘要
鄂尔多斯盆地延长组长7优质烃源岩中凝灰岩夹层广泛分布,单层厚度一般为0.1～10 cm,局部可达1～2 m。在盆地南部铜川瑶曲镇新发现了单层厚约14 m的岩屑晶屑熔结角砾凝灰岩层夹透镜状碳酸岩。熔结凝灰岩SiO_2含量在47.09%～66.6%之间,呈中性-偏酸性特征;∑REE为(164.04～245.74)×10~(-6),LREE相对富集,总体特征表现为负Eu异常明显的右倾型曲线;微量元素中大离子亲石元素Sr、P为负异常,高场强元素U、Th为明显的正异常。碳酸岩中SiO_2含量较高,矿物组成简单,可能为壳源碳酸岩; Sr和Ba的含量较高,显示典型的火成碳酸岩特征。根据熔结凝灰岩的野外露头及岩相学特征,结合其分布特征,建立了鄂尔多斯盆地中晚三叠世火山岩岩相模式,认为铜川瑶曲镇的熔结凝灰岩为火山通道相-爆发相。熔结凝灰岩源于火山弧高钾钙碱性岩浆源区,透镜状碳酸岩产生于碰撞造山过程中派生的引张大陆岩石圈断裂带,直接由岩石圈富集、地幔低程度部分熔融作用而产生的碳酸岩浆侵入或喷发所形成,与中晚三叠世秦岭造山带的演化关系密切,是秦岭造山带印支构造活动在鄂尔多斯盆地的沉积耦合效应,该发现为鄂尔多斯盆地中生代构造演化提供了新的岩石学证据。
Ignimbrite interbeds are widely distributed in the high-grade hydrocarbon source rocks in the Chang 7 member of the Yanchang Formation in the Ordos basin. Generally,a single layer is 0.1 to 10 cm thick,occasionally reaching 1 to 2 m. Field geological and microscope petrographic studies at Yaoquzhen(Tongchuan city,southern Ordos basin) have identified a ～ 14-meter thick lithic crystal ignimbrite with interbedded lensoidal carbonatite. The SiO_2 content is of 47.09% to 66.6%,which show that the rocks are primarily intermediate-felsic. Total REE(∑REE) contents are 164.04×10~(-6) to 245.74×10~(-6),and the rocks are enriched in LREEs,depleted in HREEs,with right-inclining REE pattern and negative Eu anomalies. LILEs(such as Sr and P)show negative anomalies whereas HFSEs(such as U and Th) show positive anomalies. For the carbonatites,the relatively high SiO_2 and simple mineral assemblage suggest a crustal origin,whilst the high Sr and Ba contents show an igneous origin. Based on the geological and petrographic features of the ignimbrite and their distribution characteristics,the Middle-Late Triassic volcanic lithofacies model in the Ordos basin is established and the ignimbrite is likely of volcanic feeder-explosive facies. The ignimbrite was primarily from volcanic arc and had a high-K calc-alkaline magma source. The lensoidal carbonatites may have formed during the extrusion along extensional lithospheric faults resulted from continental collision,with the carbonatites produced directly from lowdegree partial melting of the lithospheric mantle,which was intimately related to the evolution of Qinling orogenic belt that was responsible to mountain-basin coupling. The discovery provides a new petrological basis to understand the tectonic evolution of the Mesozoic Ordos basin.
Ignimbrite interbeds are widely distributed in the high-grade hydrocarbon source rocks in the Chang 7 member of the Yanchang Formation in the Ordos basin. Generally,a single layer is 0.1 to 10 cm thick,occasionally reaching 1 to 2 m. Field geological and microscope petrographic studies at Yaoquzhen(Tongchuan city,southern Ordos basin) have identified a ～ 14-meter thick lithic crystal ignimbrite with interbedded lensoidal carbonatite. The SiO_2 content is of 47.09% to 66.6%,which show that the rocks are primarily intermediate-felsic. Total REE(∑REE) contents are 164.04×10~(-6) to 245.74×10~(-6),and the rocks are enriched in LREEs,depleted in HREEs,with right-inclining REE pattern and negative Eu anomalies. LILEs(such as Sr and P)show negative anomalies whereas HFSEs(such as U and Th) show positive anomalies. For the carbonatites,the relatively high SiO_2 and simple mineral assemblage suggest a crustal origin,whilst the high Sr and Ba contents show an igneous origin. Based on the geological and petrographic features of the ignimbrite and their distribution characteristics,the Middle-Late Triassic volcanic lithofacies model in the Ordos basin is established and the ignimbrite is likely of volcanic feeder-explosive facies. The ignimbrite was primarily from volcanic arc and had a high-K calc-alkaline magma source. The lensoidal carbonatites may have formed during the extrusion along extensional lithospheric faults resulted from continental collision,with the carbonatites produced directly from lowdegree partial melting of the lithospheric mantle,which was intimately related to the evolution of Qinling orogenic belt that was responsible to mountain-basin coupling. The discovery provides a new petrological basis to understand the tectonic evolution of the Mesozoic Ordos basin.
引文
[1]张国伟,张宗清,董云鹏.秦岭造山带主要构造岩石地层单元的构造性质及其大地构造意义[J].岩石学报,1995,11(2):101-114.
[2]周鼎武,赵重远,李银德,等.鄂尔多斯盆地西南缘地质特征及其与秦岭造山带的关系[M].北京:地质出版社,1994:1-70.
[3]邓秀芹,蔺昉晓,刘显阳,等.鄂尔多斯盆地三叠系延长组沉积演化及其与早印支运动关系的探讨[J].古地理学报,2008,10(2):159-166.
[4]邓秀芹,罗安湘,张忠义,等.秦岭造山带与鄂尔多斯盆地印支期构造事件年代学对比[J].沉积学报,2013,31(6):939-953.
[5]邱欣卫,刘池洋,李元昊,等.鄂尔多斯盆地延长组凝灰岩夹层展布特征及其地质意义[J].沉积学报,2009,27(6):1138-1146.
[6]王璞珺,迟元林,刘万洙,等.松辽盆地火山岩相:类型、特征和储层意义[J].吉林大学学报(地球科学版),2003,33(4):449-456.
[7]刘池洋,赵红格,桂小军,等.鄂尔多斯盆地演化——改造的时空坐标及其成藏(矿)响应[J].地质学报,2006,80(5):617-638.
[8]张文正,杨华,彭平安,等.晚三叠世火山活动对鄂尔多斯盆地长7优质烃源岩发育的影响[J].地球化学,2009,38(6):573-582.
[9]熊林芳,刘池阳,邱欣卫,等.鄂尔多斯盆地晚三叠世构造活动及对优质烃源岩发育的影响[J].地质科技情报,2015,34(2):109-114.
[10]杨友运.印支期秦岭造山活动对鄂尔多斯盆地延长组沉积特征的影响[J].煤田地质与勘探,2004,32(5):7-9.
[11]长庆油田地质志编写组.中国石油地质志:长庆油田[M].北京:石油工业出版社,1992:80-90.
[12]SMITH I E M,JOHNSON R M.Contrasting rhyolite suites in the Late Cenozoic of Papua New Guinea[J].Journal of Geophysical Research,1981,86:10257-10272
[13]徐夕生,邱检生.火成岩岩石学[M].北京:科学出版社,2010:70-100.
[14]秦朝建,裘愉卓.岩浆(型)碳酸岩研究进展[J].地球科学进展,2001,16(4):501-507.
[15]辛后田,罗照华,刘永顺,等.塔里木东南缘阿克塔什塔格地区古远古代壳源碳酸岩的特征及其地质意义[J].地学前缘,2012,19(6):167-178.
[16]PECCERILLO A,TAYLOR S R.Geochemistry of Eocene calcalkaline volcanic rocks from the Kastamonu area,Northern Turkey[J].Contributions to Mineralogy and Petrology,1976,58(1):63-81.
[17]SUN S S,MCDONOUGH W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[J].Geological Society,London,Special Publications,1989,42(1):313-345.
[18]WOOLLEY A R,KEMPE D R C.Carbonatites:Nomenclature,average chemical composition,and elemental distribution[M]//BELL K.Carbonatites:Genesis and Evolution.London:Unwin Hyman Press,1989:1-14.
[19]PEARCE J A.Trace element characteristics of lava from destructive plate boundaries[M]//THORPE R S.Andesites:Orogenic Andesites and Related Rocks.Chichester:Wiley,1982:525-548.
[20]PEARCE J A,CANN J R.Tectonic setting of basic volcanic rocks determined using trace element analyses[J].Earth and Planetary Science Letters,1973,19(2):190-200.
[21]张国伟,张本仁,袁学诚,等.秦岭造山带与大陆动力学[M].北京:科学出版社,2001:50-120.
[22]杨学明,杨晓勇.碳酸岩的地质地球化学特征及其大地构造意义[J].地球科学进展,1998,13(5):457-466.
[23]卢欣祥,李明立,王卫,等.秦岭造山带的印支运动及印支期成矿作用[J].矿床地质,2008,27(6):762-773.
[24]陈安清,陈洪德,侯明才,等.鄂尔多斯盆地中-晚三叠世事件沉积对印支运动Ⅰ幕的指示[J].地质学报,2011,85(10):1681-1690.
(1)甘克文.鄂尔多斯地台西北部及北部震旦系至侏罗系研究初步总结报告.石油工业部银川石油管理局.1959.
(2)谢秋元,孙国凡,李云龙,等.陕甘宁盆地石油地质普查总结报告.陕西省地质局石油普查队.1974.
[2]周鼎武,赵重远,李银德,等.鄂尔多斯盆地西南缘地质特征及其与秦岭造山带的关系[M].北京:地质出版社,1994:1-70.
[3]邓秀芹,蔺昉晓,刘显阳,等.鄂尔多斯盆地三叠系延长组沉积演化及其与早印支运动关系的探讨[J].古地理学报,2008,10(2):159-166.
[4]邓秀芹,罗安湘,张忠义,等.秦岭造山带与鄂尔多斯盆地印支期构造事件年代学对比[J].沉积学报,2013,31(6):939-953.
[5]邱欣卫,刘池洋,李元昊,等.鄂尔多斯盆地延长组凝灰岩夹层展布特征及其地质意义[J].沉积学报,2009,27(6):1138-1146.
[6]王璞珺,迟元林,刘万洙,等.松辽盆地火山岩相:类型、特征和储层意义[J].吉林大学学报(地球科学版),2003,33(4):449-456.
[7]刘池洋,赵红格,桂小军,等.鄂尔多斯盆地演化——改造的时空坐标及其成藏(矿)响应[J].地质学报,2006,80(5):617-638.
[8]张文正,杨华,彭平安,等.晚三叠世火山活动对鄂尔多斯盆地长7优质烃源岩发育的影响[J].地球化学,2009,38(6):573-582.
[9]熊林芳,刘池阳,邱欣卫,等.鄂尔多斯盆地晚三叠世构造活动及对优质烃源岩发育的影响[J].地质科技情报,2015,34(2):109-114.
[10]杨友运.印支期秦岭造山活动对鄂尔多斯盆地延长组沉积特征的影响[J].煤田地质与勘探,2004,32(5):7-9.
[11]长庆油田地质志编写组.中国石油地质志:长庆油田[M].北京:石油工业出版社,1992:80-90.
[12]SMITH I E M,JOHNSON R M.Contrasting rhyolite suites in the Late Cenozoic of Papua New Guinea[J].Journal of Geophysical Research,1981,86:10257-10272
[13]徐夕生,邱检生.火成岩岩石学[M].北京:科学出版社,2010:70-100.
[14]秦朝建,裘愉卓.岩浆(型)碳酸岩研究进展[J].地球科学进展,2001,16(4):501-507.
[15]辛后田,罗照华,刘永顺,等.塔里木东南缘阿克塔什塔格地区古远古代壳源碳酸岩的特征及其地质意义[J].地学前缘,2012,19(6):167-178.
[16]PECCERILLO A,TAYLOR S R.Geochemistry of Eocene calcalkaline volcanic rocks from the Kastamonu area,Northern Turkey[J].Contributions to Mineralogy and Petrology,1976,58(1):63-81.
[17]SUN S S,MCDONOUGH W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[J].Geological Society,London,Special Publications,1989,42(1):313-345.
[18]WOOLLEY A R,KEMPE D R C.Carbonatites:Nomenclature,average chemical composition,and elemental distribution[M]//BELL K.Carbonatites:Genesis and Evolution.London:Unwin Hyman Press,1989:1-14.
[19]PEARCE J A.Trace element characteristics of lava from destructive plate boundaries[M]//THORPE R S.Andesites:Orogenic Andesites and Related Rocks.Chichester:Wiley,1982:525-548.
[20]PEARCE J A,CANN J R.Tectonic setting of basic volcanic rocks determined using trace element analyses[J].Earth and Planetary Science Letters,1973,19(2):190-200.
[21]张国伟,张本仁,袁学诚,等.秦岭造山带与大陆动力学[M].北京:科学出版社,2001:50-120.
[22]杨学明,杨晓勇.碳酸岩的地质地球化学特征及其大地构造意义[J].地球科学进展,1998,13(5):457-466.
[23]卢欣祥,李明立,王卫,等.秦岭造山带的印支运动及印支期成矿作用[J].矿床地质,2008,27(6):762-773.
[24]陈安清,陈洪德,侯明才,等.鄂尔多斯盆地中-晚三叠世事件沉积对印支运动Ⅰ幕的指示[J].地质学报,2011,85(10):1681-1690.
(1)甘克文.鄂尔多斯地台西北部及北部震旦系至侏罗系研究初步总结报告.石油工业部银川石油管理局.1959.
(2)谢秋元,孙国凡,李云龙,等.陕甘宁盆地石油地质普查总结报告.陕西省地质局石油普查队.1974.