首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 390 毫秒
1.
中国东北地区中生代火山岩岩石学特征与盆地形成   总被引:41,自引:3,他引:38  
中国东部广泛分布中生代火山岩,它是环太平洋火山作用的重要组成部分。东北地区是中生代火山岩分布最广泛的地区之一,其形成时代从晚三叠世到晚白垩世,其中晚侏罗世—早白垩世是火山作用最强烈的时期。中生代火山岩主要有高钾钙碱性火山岩系列和钾玄岩系列,并以高钾钙碱性火山岩为主。岩石类型主要有钾玄岩、安粗岩、粗面岩、橄榄粗安岩、英安岩和流纹岩。从东向西火山岩表现出了一个化学组成上的极性。岩石的Ti、Ta含量低和富K、Rb等,以及构造判别图解表明该区火山岩属造山带火山岩。上述特征表明,东北地区中生代火山活动属于与伊佐奈崎(Izanagi)板块俯冲作用有关的挤压造山。与火山岩共存的早白垩世的A型花岗岩表明,早白垩世东北地区处于拉伸构造环境。因此,松辽、海拉尔以及二连等盆地的形成与早白垩世造山带的崩塌有关。  相似文献   

2.
张鹏  张爱民 《现代地质》1997,11(2):244-252
晚侏罗世金刚台组火山岩分布在北淮阳中生代火山岩带的中部,主要岩石类型为火山碎屑岩类。据岩石化学成分,金刚台组火山岩可划分为安山质、英安质、粗面英安质和流纹质几种类型,并属于高钾钙碱性系列。其岩石化学和地球化学显示岩浆起源于下地壳,并经历了正常的分离结晶作用,有轻微的混染,岩浆开始结晶温度为936~1122℃,压力约为024GPa。据岩石地球化学方法判别,其构造环境具有类似于火山弧的特点,结合区域构造动力学背景分析,其形成可能与大别山造山带后期的陆内俯冲而引起的陆壳增厚有关  相似文献   

3.
松辽盆地东南缘中生代火山岩及其盆地形成的构造背景   总被引:9,自引:0,他引:9  
松辽盆地是我国著名的中生代盆地,在盆地的深部及其周边存在着大量火岩,在空间上和时间上火山岩和盆地之间有着密切的关系该区火山岩主要形成于晚侏罗世和早白垩世火山岩具有高钾的特征,为钙碱性火山岩系列和钾玄岩系列其岩石类型主要有:钾玄岩、响岩质碱玄岩、橄榄粗安岩、安粗岩、粗面岩、流纹岩火山岩的REE和不相容元素分布特点与造山带火山岩不相容元素的特点相似,在构造判别图解上,本区火山岩落在与俯冲作用有关的造山带火岩区域中,对火山岩的特征分析表明,本区火山岩与俯冲作用有关,本区总体构造背景与伊佐奈琦板块向东亚大陆腐冲作用有关,是一个冲造山带的构造背景  相似文献   

4.
银利沟二长岩分布于西藏羌塘西北部,岩石具有高碱、低Ti的特征,在SiO2-K2O图解中位于钾玄岩区。二长岩的锆石U-Pb同位素年龄为121.3Ma±0.6Ma,具有富集LIL、LIEE及显著的Ta-Nb-Ti负异常的地球化学特征,表现出与俯冲有关的钾玄岩的地球化学特征,形成于晚造山—后造山构造背景。这种背景很可能与冈底斯和羌塘地块在晚侏罗世—早白垩世发生的碰撞作用有关。  相似文献   

5.
松辽盆地东南缘中生代火山岩及其盆地形成的构…   总被引:7,自引:0,他引:7  
赵海玲  刘厚祥 《地球科学》1996,21(4):421-427
松辽盆地是我国著名的中生代盆地,在盆地的深部及其周边存在着大量火山岩,在空间上和时间上火山岩和盆地之间着密切的关系,该区火山岩主要形成于晚侏罗世和早白垩世,火山岩具有高钾的特征,为钙碱性火山岩系列和钾玄岩系列,其岩石类型主要有:钾玄岩,响岩质碱玄岩,橄榄粗安岩,安粗岩,粗面岩,流纹岩,火山岩的REE和不相容元素分布特点与造山带火山岩不相容元素的特点相似,在构造判别图解上,本区火山岩落在与俯冲作用有  相似文献   

6.
应用U-Pb和二次离子探针(法国产SIMS 1270)U-Pb法对大别造山带核部桃园寨火山岩中的锆石进行了年龄测定,给出其形成年龄为136~129 Ma。这一研究表明,大别造山带核部存在晚侏罗世—早白垩世火山活动和火山盆地,也说明在这一时期,该区的构造环境与北淮阳地区相似。据现残存的火山地貌和标高,及相邻的北淮阳地区的中生代火山盆地及火山沉积物的厚度,推测其剥蚀深度约 3000 m。  相似文献   

7.
银根盆地早白垩世火山岩特征及形成的大地构造环境   总被引:8,自引:0,他引:8  
根据化石组合和地层的接触关系,认为发育于银奶盆地中央隆起带两侧的苏红图组火山岩,形成于早白垩世中晚期,岩石化学成分富含SiO2,Na2O+K2O,钾钠比值(K2O/Na2O)近于1,MgOCaO〈FeO〉富集程度低,氧化程度高(Fe2O3/FeO比值大),加一套钾玄岩系列而有别于一般的碱性玄武岩,岩石类型包括粗面玄武岩,玄武粗安岩,粗安岩等,岩石化学和岩石系列表明,其形成的构造环境为陆内造山带。  相似文献   

8.
燕山造山带中生代火山喷发及岩浆演化   总被引:4,自引:2,他引:2  
燕山造山带是中国东部中生代火山活动最强烈的地区之一,火山喷发主要有早侏罗世南大岭阶段、晚侏罗世髫髻山阶段、早白垩世东岭台阶段和东狼沟阶段。多阶段火山喷发可分为早侏罗世近EW向喷发带、晚侏罗世NE向喷发带和早白垩世NNE向喷发带。火山—沉积盆地主要有早侏罗世继承性坳陷盆地、晚侏罗世继承性断陷盆地、早白垩世新生性上叠式断陷盆地。火山喷发主要有南大岭阶段夏威夷型喷发、髫髻山阶段斯特朗博利型喷发、东岭台阶段普林尼型喷发3种类型。岩浆成分变化规律为:早侏罗世南大岭阶段以基性岩浆为主, 晚侏罗世髫髻山阶段中性岩浆规模大, 早白垩世东岭台阶段酸性岩浆活动强烈。  相似文献   

9.
辽西地区中生代盆地构造演化   总被引:7,自引:1,他引:7  
杨庚  郭华  刘立 《铀矿地质》2001,17(6):332-340
辽西地区为华北地台北缘阴山-燕山造山带的东延部分,中生代发育火山-碎屑岩沉积盆地。盆地地质分析表明,该区在早白垩世早期之前发育的沉积盆地为挤压型盆地,早白垩世中期以后属伸展断陷盆地。根据沉积-构造分析,该区中生代盆地构造演化可划分为5个构造演化阶段;(1)早三叠世--早侏罗世;(2)早侏罗世-中侏罗世;(3)中侏罗世-晚侏罗世;(4)早白垩世早期;(5)早白垩世中期-晚白垩世。  相似文献   

10.
西藏安多地区粗面岩的特征及其锆石SHRIMP U-Pb定年   总被引:3,自引:2,他引:1  
安多粗面岩位于班公湖-怒江缝合带中段,紧邻安多蛇绿岩带的北侧,出露面积约30km2,堆积厚度约1500m,属陆相火山岩。火山机构面貌保存较完整。岩石类型包括安粗岩、石英安粗岩、粗面岩及少量火山碎屑岩,以粗面岩为主,属钾玄岩系列。岩石地球化学和同位素示踪特征表明岩石属相对高压型的粗面岩,是与大陆碰撞后造山有关的钾质火山岩。岩浆主要来源于加厚的陆壳下部,但也有幔源组分的贡献。粗面岩中锆石SHRIMP U-Pb年龄为79.9Ma±1.9Ma,是粗面质岩浆上侵结晶的年龄,表明安多粗面岩的喷溢时代为晚白垩世, 也暗示班公湖-怒江洋盆安多段早白垩世晚期已经闭合,晚白垩世时期羌塘地块与拉萨地块已成为统一的陆块,并具有加厚的陆壳。  相似文献   

11.
The Dabie orogenic belt underwent deep subduc-tion of continent, rapid exhumation, and huge amount of erosion during the Mesozoic. Its tectonic evolution, especially how that was recorded in sedimentary ba-sins at the flanks of the Dabie orogenic belt is one of the most important issues. The overall distribution of different basin types in the orogenic belt indicates that shortening and thrusting at the margins of the orogenic belt from the Late Triassic to the Early Cretaceous controlled the foreland basins, and extension, doming and rifting were initiated in the core of the orogenic belt from the Jurassic to the Early Cretaceous, and were expanded to the whole orogenic belt after the Late Cretaceous.  相似文献   

12.
在合肥盆地南缘广泛分布的中生界内,砾石主要由变质岩碎屑组成。碎屑在地层中分布及垂向上的变化,为重塑造山带折返剥露历史提供了证据。防虎山组和三尖铺组底部砾岩碎屑组合为:石英片岩+云母片岩+石墨片岩+千枚岩+石英岩+脉石英+片麻岩(局部),表明在早侏罗世晚期Pliensbachian期(距今195Ma)之前,佛子岭群和卢镇关群已经折返到地表并遭受剥露。早白垩世凤凰台组、毛坦厂组和周公山组中砾岩碎屑组合为:片岩+石英岩+片麻岩+混合岩+榴辉岩+角闪岩+斜长岩+花岗岩+大理岩等,榴辉岩以及其它基性岩的微量元素特征表明它们可能是一个在早白垩世以前(距今135Ma)折返到地表并遭受完全剥露,而现在已经从造山带消失的超高压构造地层单元。大别造山带出露的超高压变质带(大别杂岩)在北缘中生代地层中目前尚未发现有可靠的沉积记录,推测它们的大规模折返和剥露可能在新生代,并持续到现在。据此认为大别造山带大规模的折返剥露分为3个阶段:早侏罗世之前、晚侏罗世—早白垩世早期和新生代。  相似文献   

13.
杨欣  李双应 《地质科学》2011,46(2):308-321
以造山带为物源区的周缘盆地中的沉积物记录着物源区的成分特征,保存着造山带的演化历史.根据地层资料,利用质量平衡方法得到大别造山带周缘的合肥盆地、江汉盆地、安庆-潜山盆地和信阳盆地在侏罗-白垩纪的沉积总量为1.685×105km3.大别造山带周缘盆地的平均沉积速率分别为早侏罗世0.407×106 m3/a,中晚侏罗世0....  相似文献   

14.
《International Geology Review》2012,54(11):1417-1442
ABSTRACT

The Ordos Basin, situated in the western part of the North China Craton, preserves the 150-million-year history of North China Craton disruption. Those sedimentary sources from Late Triassic to early Middle Jurassic are controlled by the southern Qinling orogenic belt and northern Yinshan orogenic belt. The Middle and Late Jurassic deposits are received from south, north, east, and west of the Ordos Basin. The Cretaceous deposits are composed of aeolian deposits, probably derived from the plateau to the east. The Ordos Basin records four stages of volcanism in the Mesozoic–Late Triassic (230–220 Ma), Early Jurassic (176 Ma), Middle Jurassic (161 Ma), and Early Cretaceous (132 Ma). Late Triassic and Early Jurassic tuff develop in the southern part of the Ordos Basin, Middle Jurassic in the northeastern part, while Early Cretaceous volcanic rocks have a banding distribution along the eastern part. Mesozoic tectonic evolution can be divided into five stages according to sedimentary and volcanic records: Late Triassic extension in a N–S direction (230–220 Ma), Late Triassic compression in a N–S direction (220–210 Ma), Late Triassic–Early Jurassic–Middle Jurassic extension in a N–S direction (210–168 Ma), Late Jurassic–Early Cretaceous compression in both N–S and E–W directions (168–136 Ma), and Early Cretaceous extension in a NE–SW direction (136–132 Ma).  相似文献   

15.
A zircon U-Pb geochronological study on the volcanic rocks reveals that both of the Zhangjiakou and Yixian Formations, northern Hebei Province, are of the Early Cretaceous, with ages of 135-130 Ma and 129-120 Ma, respectively. It is pointed out that the ages of sedimentary basins and volcanism in the northern Hebei -western Liaoning area become younger from west to east, i. e. the volcanism of the Luanping Basin commenced at c. 135 Ma, the Luotuo Mount area of the Chengde Basin c. 130 Ma, and western Liaoning c. 128 Ma. With a correlation of geochronological stratigraphy and biostratigraphy, we deduce that the Xing‘anling Group, which comprises the Great Hinggan Mountains volcanic rock belt in eastern China, is predominantly of the early-middle Early Cretaceous, while the Jiande and Shimaoshan Groups and their equivalents, which form the volcanic rock belt in the southeastern coast area of China, are of the mid-late Early Cretaceous, and both the Jehol and Jiande Biotas are of the Early Cretaceous, not Late Jurassic or Late Jurassic-Early Cretaceous. Combining the characteristics of the volcanic rocks and, in a large area, hiatus in the strata of the Late Jurassic or Late Jurassic-early Early Cretaceous between the formations mentioned above and the underlying sequences, we can make the conclusion that, in the Late Jurassic-early Early Cretaceous, the eastern China region was of high relief or plateau, where widespread post-orogenic volcanic series of the Early Cretaceous obviously became younger from inland in the west to continental margin in the east. This is not the result of an oceanward accretion of the subduction belt between the Paleo-Pacific ocean plate and the Asian continent, but rather reflects the extension feature, i.e. after the closure of the Paleo-Pacific ocean, the Paleo-Pacific ancient continent collided with the Asian continent and reached the peak of orogenesis, and then the compression waned and resulted in the retreating of the post-orogenic extension from outer orogenic zone to inner part (or collision zone). The determination of the eruption age of the volcanics of the Zhangjiakou Formation definitely constrains the switch period, which began in the Indosinian and finished in the Yanshanian, that is, 140-135 Ma. The switch is concretely the change from the approximate E-W Paleo-Asian tectonic system to the NE to NNE Pacific system, and the period is also the apex of a continent-continent collision and orogenesis of subduction, being consumed and eventually disappearing of the Paleo-Pacific ancient continent, and all the processes commenced in the Indosinian. While the following post-orogenic large-scale eruption in the Early Cretaceous marks the final completeness of the Paleo-Pacific structure dynamics system.  相似文献   

16.
冈底斯带晚中生代构造演化模式一直存在争议。此次研究了中冈底斯带扎布耶茶卡北部区域则弄群火山岩的野外特 征和锆石U-Pb年龄。锆石U-Pb定年结果表明,扎布耶茶卡北部则弄群火山岩主要喷发于154.2~142.1 Ma。研究首次获得 晚侏罗世的则弄群火山岩年龄为154 Ma,比前人提出的则弄群火山岩浆活动起始时间(130 Ma) 提前了24 Ma,据此将则 弄群的时代定为晚侏罗世至早白垩世。根据研究获得的最新年代学数据,结合冈底斯带火山岩的前人研究资料,显示冈底 斯带中生代弧火山岩具有从南向北逐渐年轻的趋势。因此,最早期南冈底斯弧中生代火山岩可能与新特提斯洋板片北向俯 冲有关,晚侏罗世至早白垩世的中冈底斯带弧火山岩受到了新特提斯洋板片北向俯冲和班公湖-怒江洋板片南向俯冲的双 重影响,早白垩世中期的北冈底斯带弧火山岩则与班公湖-怒江洋板片的南向俯冲密切相关。研究成果为冈底斯带晚中生 代构造演化模式提供了火山岩方面的新证据。  相似文献   

17.
The East Qinling–Dabie orogenic belt accommodates the largest Mo ore district in the world. It contains 8.43 Mt of proven Mo metal reserves which accounts for 66% of the total proven Chinese Mo reserves. The Mo ore district includes 24 deposits and 12 occurrences, with four major types of Mo mineral systems, i.e., porphyry, porphyry-skarn, skarn and hydrothermal veins. The latter can be further subdivided into quartz vein and carbonatite vein types. Although Mo mineralization in the belt began in the Paleoproterozoic (1680 ± 24 to 2044 ± 14 Ma), all economically significant deposits were formed during the Mesozoic. Re/Os dating of molybdenite has shown that there are three episodes of Mo mineralization, i.e., Late Triassic (233–221 Ma), Late Jurassic to Early Cretaceous (148–138 Ma) and Early to middle Cretaceous (131–112 Ma).Late Triassic Mo deposits developed as molybdenite–quartz veins and carbonatite vein types. Stable isotope systematics (C, O, S) and high contents of Re and Sr indicate that the carbonatite Mo veins are mantle-derived. Porphyry and porphyry–skarn Mo mineral deposits were formed in the Late Jurassic to Early Cretaceous and Early to middle Cretaceous. The Late Jurassic to Early Cretaceous granite porphyries that are associated with the Mo deposits usually occupy less than 1.5 km2 at the surface and are situated in the East Qinling area, far west of China's continental margin. On the other hand, the Early to middle Cretaceous batholiths and granite porphyries, , with associated Mo deposits are located in the Dabieshan area and eastern part of the East Qinling area. The Late Jurassic to Early Creataceous granitoids and related Mo deposits possibly formed in a back-arc extensional setting of the Eurasian continental margin, which was probably triggered by the oblique subduction of the Izanagi plate. The Early to middle Cretaceous batholiths and granite porphyries are linked to the tectonic regime of lithospheric thinning, asthenospheric upwelling and partial melting of the crust, induced by a change in Izanagi Plate motion parallel to the continent margin.In the East Qinling–Dabie belt there are vein type Pb–Zn–Ag deposits surrounding porphyry and/or porphyry–skarn Mo (W) deposits, forming well defined ore clusters. The same spatial arrangement (i.e., porphyry Mo stockworks and outlying Pb–Zn–Ag ore veins) is also observed at the deposit scale. Thus, Mo porphyry stockworks and distal polymetallic veins belong to the same ore system and may reflect an outward temperature decrease from the highly fractionated granite plutons. Both, porphyry stockworks and polymetallic veins, can be used as vectors for further prospecting.  相似文献   

18.
大别山北缘地区发育厚达近万米的中新生代碎屑岩,它们记录着大别山造山带和在株罗纪以来的演化历史。在安徽省六安地区毛坦厂组中,发现多块榴辉岩砾石。砾石新鲜,质地坚硬,表明属于第一旋回砾石。榴辉岩由石榴子石、多硅白云母、绿帘石、石英、金红石等组成。具有明显的退变质作用,发育以钠长石和闪石类组成的后合成晶、以及石榴子石周边的次为边。石榴子石以铁铝榴石和钙铝榴石为主,恪地C类榴辉岩。根据其特征应该属于大别山南部和北部超高压榴辉岩。毛坦厂组层位确切,古生物化石和同位素年龄都表明以晚株罗世为主,这一发现表明,在晚株罗世,以榴辉岩为代表的造山带根部物质,即:超高压变质岩已经出露地表,并作为毛坦厂组的物源。因此,大别造山带超高压为质岩折返到地表,最迟在晚株罗世。  相似文献   

19.
首编大别造山带侵入岩地质图(1∶50万)及其说明   总被引:1,自引:0,他引:1  
大别造山带侵入岩出露面积占该区总面积的50%左右,不同时代的侵入岩是重塑造山带演化历史的窗口。报道了新编绘的《大别造山带及邻区侵入岩地质图(1∶50万)》的编制过程及其意义。该图反映了大别造山带侵入岩的空间分布、侵位时代、岩石类型和地球化学特征。同时,为了方便查阅,对出露的侵入岩体进行了编号。研究表明,大别造山带及邻区的侵入岩侵位时代以早白垩世为主,并有少量晚侏罗世、新元古代和早古生代岩体。新元古代岩体主要呈岩株状产出于南大别和西大别红安地区,北淮阳地区亦有少量分布;早古生代侵入岩类规模较小,主要于奥陶纪—志留纪时期侵位,分别呈带状分布于造山带的南北两侧,形成双岩浆带;晚侏罗世岩体主要分布在大别山以南的长江中下游地区;早白垩世侵入岩类分布广泛,面积约占整个大别造山带的47%。认为晚中生代岩浆活动与太平洋板块同期向北西方向的俯冲和随后的伸展事件密切相关。  相似文献   

20.
燕山地区土城子组划分、时代与盆地性质探讨   总被引:13,自引:2,他引:13       下载免费PDF全文
燕山地区土城子组分布广泛,顶底清晰,是本区最具特色的岩石地层单位之一。区域地质对比研究表明,燕山西部土城子组与燕山中东部土城子组在地层、时代上有较大的不同,西部盆地中髫髻山组火山岩不发育或很少发育,土城子组在地层划分上常包含九龙山组或髫髻山期火山岩,时代为中晚侏罗世(J2—J3);东部盆地普遍发育髫髻山组火山岩浆或火山-沉积地层,土城子组划分与层型剖面一致。古生物化石和同位素年龄研究表明:土城子组时限在156~139Ma之间,属于晚侏罗世—早白垩世。土城子期盆地沉积的不对称性,相分布特征,古水流等指示其形成在一个挤压作用下的陆内火山-沉积盆地环境。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号