Hercynian-Indosinian Sedimento-Tectonic Evolution of the Nanpanjiang Basin

Following the orogeny in the Early Palaeozoic, the tectonic evolution of the Nanpanjiang basin in the Hercynian-Indosinian stage constituted a complete Wilson Cycle, made up of the stages of early rifting (D-P1), late rifting and passive margin developement (P2-T1), and peripheral foreland basin developement (T2-T3). The REE data of the initial Early Triassic basalts from the southern part of the basin has verified the existence of the oceanic crust once in the basinal evolution. The basin developed into a foreland one in the Middle-Late Triassic, indicating that the Yangtze plate once collided with the Indo-Sinian plate along the Black River fracture zone.

FROM BACK-ARC BASIN TO BACK-ARC FORELAND BASIN—THE SEDIMENTARY BASIN AND TECTONIC EVOLUTION OF THE LATE CALEDONIAN—EARLY HERCYNIAN STAGES IN CORRIDOR AND NORTH QILIAN MTS

Qilian orogenic belt is a typical orogenic belt formed by polycyclic collisions between the North China plate and Qaidam microplate. Qilian ocean originated from the rift of the late Proterozoic Rodinia continent(Pangea\|850), evolved through rift basin and became an archipelagic ocean in the Caledonian stage. The Lower Proterozoic strata in Qilian area are mid\|high\|rank metamorphic rocks that constitute the metamorphic basement of the area. The “Huangyuan Movement" (in South Qilian and Central Qilian) and "Alashan Movement" (in North Qilian) in the latest Late Proterozoic formed a regional unconformity. The middle Proterozoic in the area are mudstones and carbonate rocks with stromatolites and ooids. The Qingbaikou System of the upper Proterozoic in the North Qilian and Corridor region is also mudstone and carbonate rock with stromatolites. The Qingbaikou System in Central Qilian is sandstones and mudstones. There are alkaline and tholeiite in the Sinian System in North Qilian and Corridor. The contact between Qingbaikou System and Sinian System is a regional unconformity (Quanji Movement). Qilian ocean began to rift away in Caledonian tectonic stage on the Pre\|Sinian basement.

THE EXTENSIONAL MOVEMENT AND ACTION IN THE SOUTHERN TIBET SINCE HERCYNIAN

Based on the study of the location of extensional action in the tectonic background and the state of regional tectonic stress, the extensional action can be distinguished into active and passive types. The active extensional movement is mainly composed of a set of deposition formed under extensional stress and syntectonic and syndepositional deformational structure. The passive extentional movement is expressed as regional extensional action induced under the compressional elevation. Extensional movement and action are well\|developed in the Tibet\|Tethys domain. By the analysis of tectonic deformation, extensional unconformity, depositional facies and paleogeographical rebuilding in the South Tibet, it is recognized that the extensional movement consists of active extension of Hercynian, Indo\|China and Early Yanshan epochs, and the passive extension of Late Yanshan and Himalayan epochs. Some of the characteristics of extensional movement and structures are discussed in this paper(Table.1).

新疆阿尔泰造山带海西期花岗伟晶岩地球化学特征、年代学及地质意义

阿尔泰是我国也是世界上最重要的伟晶岩分布区,伟晶岩作为一种独立的矿床类型,在矿床学研究中具有重要意义。本次研究选择阿尔泰造山带西段布尔津冬格列伟晶岩和青河北伟晶岩为研究对象,获得LA-ICP-MS锆石U-Pb年龄为(343.7±1.7)Ma,为早石炭世海西期运动产物。地球化学特征显示,伟晶岩具富硅、过铝质、中碱、中钙等特征,具低钾系列向高钾钙碱性系列过渡的特征。微量元素具有Ba,Ta,Nb,Sr,Zr,Ti相对负异常,Rb,K,Nb,P,Hf,Y相对正异常特征,接近原始地幔。分布曲线为“海鸥型”分布型式,具“四重效应”特征。稀土含量较低,轻重稀土分馏中等,轻稀土分馏明显,重稀土分馏不明显,分布曲线为右倾型,呈“V”型谷状。成因类型为分异变质成因伟晶岩,为NYF型。形成于俯冲增生阶段,处于挤压环境,构造活动强烈,不利于流动性很强的熔体-流体稳定,不易形成稀有金属伟晶岩矿床。

Hercynian Orogenic Fold Belts and the Terrane Tectonics in Northern Xinjiang, China

There are eight Hercynian orogenic fold belts in northern Xinjiang. The traditional viewpoint is that the orogeny was related to collision between the Siberian plate, Kazakhstan-Junggar and Tarim-Sinokorean plates. The recent investigation indicates that in northern Xinjiang, geological entity of continental plate did not exist during the Hercynian cycle. It is suggested that the orogenic processes in this area are the results of displacement and accretion between the Tarim terrane, Junggar terrane, central Tianshan (Ili-Isaik Lake)

The First Discovery of a Tin Deposit Related to Hercynian A-Type Granites in China

This paper introduces the petrological, mineralogical and geochemical fea. tures of the rocks hosting the Sareshik tin deposit—an independent tin deposit related to Hercynian A-type granites discovered in China in 1987. A comparison with the features of A-type granites at home and abroad indicates that some of their petrological features are more typical than those of famous A-type granites of Nigeria. The geological features of the tin deposit are salient and notably different from those of some famous tin deposits in China, so the deposit may represent China’s deposits associated with anorogenic granites. This tin deposit was formed in the Hercynian Stage. This type of tin deposit was for the first time discovered in China and is also rare in the world. It is a new type of tin deposit in China.

Identification of Hercynian shoshonitic intrusive rocks in central Hainan Island and its geotectonic implications

An identification has been made of some shoshonitic intrusive rocks in central Hainan Island recently. These rocks are K-rich (K2O=2.9%―5.1%, K2O/Na2O=0.95―2.12), distinctly enriched in LILE and LREE, strongly depleted in Nb, Ta, and moder- ately depleted in Sr and Ti, with (87Sr/86Sr)i = 0.70859―0.71425 and ε Nd(t) = (?2.77―?7.49). They were derived from an EMⅡ-type mantle source. The enrichment process is related to metasomatism of depleted mantle caused by a great amount of fluid-melt released from oceanic crust and terri- genous sediments at great depth (eclogite facies) during the subduction of the South China plate under the Indochina-South China Sea plate in the Carbon- iferous–Early Permian. A SHRIMP U-Pb zircon dating yields a crystallization age of 272±7 Ma for the sho- shonitic intrusions, which is coeval with the strongly peraluminous granites found in central Hainan Island. These two kinds of rocks generally possess syn-intrusion ductile deformation structures. Thus they are considered to have been generated during the early stage (syn-thrust phase) of a post-collisional event. The primary magma of shoshonitic rocks was produced at a depth > 80 km by decompression- dehydration melting of previously enriched litho- spheric mantle wedge, phlogopite-bearing garnet peridotite, which was in turn caused by the break-off of a descendent slab and upwelling of a hot as- thenosphere. The rising of melts was accompaniedby crustal contamination and crystallization fractiona- tion (AFC). Combining with other related data, it is proposed that the southwards subduction and amal- gamation of the South China plate with the Indo- China-South China Sea plate took place at ca. 287- 278 Ma, which was a part of the convergence proc- ess of the Pangea supercontinent. The suture zone was probably located along the line of Song Ma-Beibu Gulf-north margin of the Yunkai Moun- tains-Wuyi Mountains.

塔河油田岩溶峡谷区伏流坍塌型古暗河缝洞系统

为研究塔河油田中—下奥陶统古岩溶发育特征,通过恢复海西运动早期古地貌和古水系,划分了岩溶峡谷区洞穴类型,构建了塔河油田岩溶峡谷区伏流坍塌型缝洞成因演化模式。研究结果表明:研究区发育海西运动早期古岩溶作用,岩溶古地貌总体北东高南西低,微地貌以低幅度溶丘、溶峰和洼地的组合为主,古水系主要为峡谷明流、伏流、暗河与干谷的组合;主干水系具有南段深切曲流峡谷、中段峡谷和北段伏流-天窗的分段结构,分支水系为树枝状暗河网络;伏流坍塌型地下河洞穴可识别,划分为暗河型、伏流型、顺河潜流型和穿洞型4种类型;研究区古暗河系统发育演化可分自由曲流型、伏流-深切曲流型和坍塌天窗伏流型。

Geodynamic Indications on Igneous Rocks of Transitory Geologic Setting during the Late Hercynian in North Tarim Basin

Basic and intermediate-acidic igneous rocks were developed during the late Hercynian in North Tarim basin. The geochemistry characteristics of the rocks show that basic volcanic rock has K2O/Na2O = 0.18-0.61 < 1 and falls into a category of basalt of sodium system. The rocks contain en- riched large-ion lithophile elements (LILE) (K, Rb, Ba, Th) and high-field strength elements (HFSE) (Nb, Ta, Ti, Zr, P), with the magmatic material from the upper mantle. The intermediate-acidic volcanic rocks have σ = 1.91-2.96 < 3.3, K2O/Na2O = 1.25-1.59 > 1, as well as the enriched LILE and depleted HFSE (Nb, Ta, Ti, P), presenting the same trace element compositions and character- istics as in the granitic rocks of South Tianshan Mt.; they are either shoshonitic igneous rocks or high-K calc-alkaline igneous rocks, with a distinct crust-derived component feature. The comprehensive analyses on the characteristics of the trace elements, the graphic tectonic dis-crimination, and the distribution features of the two types of igneous rocks show that they were formed under different tectonic settings and geodynamic environments: the basalt was formed in the active rifting period when the active mantle upwelling caused the thinning of lithosphere; the intermediate-acidic volcanic-intrusive rock was formed in the island arc area of the active continental margin in North Tarim; the formation is associated with the plate subduction during the course of South Tian- shan Ocean closure-the subduction of Middle Tianshan Mountain toward the Tarim plate. The basic and intermediate-acidic igneous rocks reveal a tectonic regime of extension-extrusion transition, which is significant in determining the key tectonic revolution period of North Tarim basin.

四川盆地西部二叠系多期台缘带油气勘探潜力

四川盆地西部二叠纪时期位于稳定克拉通边缘,受到海西运动、东吴运动和峨眉地裂运动的共同作用,发生构造-沉积分异。本文采用构造控盆、盆地控相、相控成藏要素组合的研究思路,在川西地区开展新一轮研究工作,揭示了二叠纪构造-沉积分异对油气成藏的控制作用,明确川西地区海相碳酸盐岩油气勘探潜力。盆地二叠纪以拉张伸展背景为主,总体呈现“南部隆升、西部裂陷、北部拉张”的沉积格局。二叠纪多期构造运动共同导致了川西地区一系列台内裂陷的形成,叠加二叠纪时期海平面变化,控制了栖霞至长兴期的多期台缘发育。川西北地区发育北东—南西向和北西—南东向两组断裂体系控制该区岩相古地理格局,其中龙门山断裂带主要控制了泥盆纪至二叠纪栖霞期沿上扬子台地西北缘发育台缘带,呈北东向展布。茅口至长兴期台缘带受克拉通边缘及台内裂陷共同控制,在川西地区呈北东向展布,梓潼—老关庙地区沿裂陷发育呈北西向展布,在剑阁一带,栖霞、茅口、吴家坪和长兴组多期台缘带叠置发育。川西地区二叠纪多期台缘控制了多层系优质滩相储层和礁储层叠置发育,是川西地区二叠系规模孔隙型储层发育的主控因素。多期古裂陷、多期台缘带和成藏期大型古隆起三元素耦合有利于油气规模聚集成藏。川西多层系台缘带具有纵向叠置,平面呈北东向大面积展布的特征,具备万亿规模资源潜力,是四川盆地海相碳酸盐岩重要勘探接替领域。

塔河油田海西运动早期岩溶水系统划分及特征

塔里木盆地塔河油田中—下奥陶统海西运动早期地表及地下岩溶形态多样,地下岩溶缝洞系统中油气资源丰富。根据高精度地震资料及钻井资料,统一地下及地表水系统,构建了塔河油田中—下奥陶统海西运动早期岩溶水系统。研究结果表明:塔河油田中—下奥陶统在海西运动早期发育4个岩溶台地,总体呈东高西低阶梯分布,岩溶水差异化排泄和溶蚀作用造成各岩溶台地发育峡谷、伏流、深切曲流、宽谷等不同水文地貌形态;岩溶水系统的边界主要为地表分水岭、排泄基准面、地层岩性组合、断裂和弱溶蚀带;塔河油田岩溶水系统划分为4个相对独立的二级岩溶水系统,分别为高原峡谷水系统、伏流峡谷水系统、深切曲流水系统和宽谷水系统;岩溶水系统层级结构的划分为深化塔河油田岩溶缝洞系统和岩溶缝洞单元认识提供地质依据。

Trace-element geochemistry and S–O isotopes in the fluorite-barite mineralization of Merguechoum,Moroccan eastern Meseta:insights into ore genesis to the Pangea rifting

The Merguechoum fluorite-barite mineralization,located in the Eastern Meseta of Morocco,is hosted in the Late Hercynian granite.The ore consists of fine crystals of fluorite 1,massive barite 1,euhedral crystals of fluorite 2,and barite 2 with calcite and minor quartz and sulfides.The Merguechoum ore deposits have never been investigated.This study was the first contribution that studied the genesis of fluorite and barite.The ore occurs as dissemination within granite intrusion and also fills the NE-SWtrending meter-sized fractures and faults.The values of the total Rare Earth Elements and Yttrium(REY)and the ratios of LREY/HREY,Y/Ho,Tb/Ca,and Tb/La indicate that the Merguechoum fluorite precipitated from hydrothermal fluids,likely basinal brines,which interacted with the Hercynian granite.The REY data indicate that the ore-forming fluids of the early stage have intensely interacted with the Hercynian granite compared to those of the late ore stage.The gradual decrease in the europium(Eu/Eu^(*)),yttrium(Y/Y^(*)),and cerium(Ce/Ce^(*))anomalies and a low concentration ofΣREY observed in the second ore stage compared to the first ore stage suggest an increase in p H and fO_(2)and by inference a decrease in temperature during the evolution of the hydrothermal system.This evolution could be explained by fluid mixing between the ascending basinal hydrothermal fluids and the diluted sulfate-rich meteoric water barite separates from selected samples reveal that the dissolved sulfates(SO_(4)^(2-))were derived from Permian–Triassic sulfates and/or coeval poreseawater sulfates.The proposed fluid mixing triggered the precipitation of an early-stage F-Ba assemblage followed by the second-stage F-Ba mineralization.Geologic fieldwork,REY inventories,and isotope data point to the ore genesis during the Permian–Triassic extensional tectonic activity concerning the Pangea rifting.This extensional tectonic environment is likely the driving force that mobilized a large amount of the ore-forming basinal brines along the available faults and fractures to the loci of ore deposition.

塔里木盆地早海西期多期次风化壳岩溶洞穴层

洞穴层是识别多期次岩溶旋回的标志,是岩溶旋回连接沉积旋回及周期性海平面变化的纽带。本文通过古地貌恢复,将从钻井剖面中识别的洞穴层归位到早石炭世古地貌剖面中,根据洞穴层总是沿稳定古潜水面发育的特点划分对比洞穴层。通过洞穴层的形成条件、充填结构分析,推断洞穴层发育序次、洞穴层与其同时期形成的沉积地层的时空对应关系,并据此对洞穴层进行盆地范围内跨地区对比、总结斜坡及岛屿两种不同的洞穴层发育模式。研究结果表明,在早海西期,塔北、塔中、和田古隆起中、下奥陶统碳酸盐岩陆块内部发育了3个期次的风化壳岩溶洞穴层,其序次为下老上新,它们是在早石炭世间歇性海平面上升过程中形成的,其同时期形成的沉积地层分别为下石炭统东河砂岩段、生屑灰岩段、下泥岩段中上部。洞穴层内部多旋回“坍塌角砾-地下河沉积”组合是斜坡内陆区潜流面的迟后上升效应,洞穴层与洞穴等时层的时空对应关系对于大型古岩溶事件的断年及洞穴层的分布预测具有重要意义。

塔里木盆地哈拉哈塘地区碳酸盐岩油气地质特征与富集成藏研究

塔里木盆地塔北隆起哈拉哈塘地区奥陶系由于现今构造位置低,埋深在6500～8000m,长期以来一直将其作为塔北隆起的一个次级凹陷单元,并认为是一个海相油气的生烃凹陷,制约了哈拉哈塘的油气勘探。本文通过对哈拉哈塘构造解析和沉降演化过程恢复,发现哈拉哈塘地区是从石炭纪才开始转为负向构造单元,加里东-早海西期,它属于轮南大型古潜山的西斜坡部位;奥陶系鹰山组-一间房组碳酸盐岩经历了多期岩溶的叠加改造,风化岩溶缝洞体储层发育。通过最新钻井资料及油气地球化学分析数据,证实哈拉哈塘奥陶系沉积时期不是生烃凹陷,不发育烃源岩,哈拉哈塘及其以北地区的油气是来自南部满西地区的中、上奥陶统烃源岩。油气藏解剖表明,哈拉哈塘地区在晚海西期成藏;三叠系沉积前北部构造抬升,导致奥陶系油藏遭受局部破坏和降解。自三叠纪沉积以来,奥陶系油藏一直处于持续深埋过程,盖层不断加厚,油藏基本保持了晚海西期成藏时的形态,因此,哈拉哈塘地区是一个古老的油气系统。油气成藏条件分析表明,哈拉哈塘地区油气成藏条件优越,生储盖条件配置良好,奥陶系碳酸盐岩岩溶储层广泛分布,并处在油气向古隆起高部位运移的有利路径上,具有大面积、准层状富集油气的特征。

天山海西期不同类型花岗岩类岩石化学特征及其地球动力学意义

通过研究把天山海西期花岗岩类分为 4类 :幔源 (M)型、同熔 (SY)型、改造型[混合改造 (MT)亚型、富铝改造 (PT)亚型和富钾改造 (KT)亚型 ]和 A型。对各类花岗岩的地质特征和岩石化学特征进行分析 ,总结出其时空演化规律。随时代的变新 ,从幔源型到 A型 ,基性程度降低、碱质含量增高、规模由小变大再变小。就同熔型花岗岩而言 ,基性程度中天山 >北天山 >南天山 ;富钾改造亚型与同熔型变化的特点相反 ,酸性程度中天山>北天山 >南天山 ;富铝改造亚型在天山各区呈现岩石化学特征基本相似的特点。天山海西期花岗岩类岩石化学特点及时空规律表明 :1)天山造山带花岗岩类的演化序列为 :幔源型 -同熔型 -改造型 (混合改造亚型 -富铝改造亚型 -富钾改造亚型 ) - A型。 2 )花岗岩类演化序列表征了造山带花岗岩成分定向演化的规律 ,是陆壳增生和其成熟度渐高的例证。 3)“造山岩”的含义应界定为同熔型和改造型花岗岩类 ,天山海西期花岗岩分布的不均一性由各构造单元的性质不同所造成。 4 )富铝改造亚型花岗岩类是陆块碰撞拼合的标志。 5 )富钾改造亚型花岗岩类花岗岩为碰撞造山减压达到高潮的标志。 6 ) A型花岗岩的发育是造山运动结束的标志。

青藏高原东北缘印支期宗务隆造山带

位于柴达木地块北缘构造带(柴北缘构造带)与南祁连造山带间的宗务隆构造带发育晚古生代、早中三叠世地层以及石炭纪蛇绿岩地体和具有岛弧性质的二叠纪—早三叠世中酸性火山岩。三个侵入宗务隆带南侧的海西—印支期花岗岩(246Ma天峻南山花岗岩、238Ma青海湖南山花岗岩和215Ma二郎洞花岗岩)分别与俯冲和后碰撞相关。两期明显的构造变形为印支期造山构造和第三纪陆内构造活动印记,前者以300余公里长的韧性剪切带为代表,后者以大规模指向南的逆冲推覆作用为特征。宗务隆构造带经历了由陆内裂陷、洋盆发育和俯冲—碰撞造山的演化过程,既不同于其南侧的柴北缘构造带也不属于北侧的南祁连造山带,而是一在柴北缘和南祁连造山带共同构建的加里东陆块上发育起来的、具有完整板块旋回的印支期造山带。

塔里木北缘及邻区海西期碱性岩岩石化学特征及其大地构造意义

塔里木地台北缘及邻区发育一套以正长岩、石英正长岩、霓辉正长岩、霓霞正长岩、碱性花岗岩类为代表,包括碱性辉长岩、碱长花岗岩、霓辉花岗岩、角闪正长岩、碱性辉石闪长岩、煌斑岩等类岩石在内的碱性侵入岩体.它们具有近东西向的带状分布特征.主体形成于海西期,相当于泥盆—二叠纪.钾钠含量较高,具有碱性岩类的岩石化学特征,构成一条碱性侵入岩带.其时空分布与北山—阿拉善地区的碱性岩带基本一致.该碱性岩带反映出在泥盆—二叠纪期间,塔里木地台北缘及邻区处于造山期后的拉张构造环境.

中上扬子克拉通海西-印支期(泥盆纪-中三叠世)沉积层序充填过程与演化模式

以"构造控盆、盆地控相、相控组合"的思路和"过程-响应"原理为指导,即壳-幔耦合、板块活动和构造运动形成盆地,盆地沉积充填形成层序与相带组合的时空展布,而不同级别层序格架中层序结构、体系域叠加样式及相带的时空组合与盆地沉积充填过程密切相关。在前人对中上扬子克拉通盆地取得丰富的研究与勘探成果基础上,加强沉积环境、层序结构与沉积充填过程等方面的研究,对深化研究区认识以及油气资源勘探具有重要意义。因此,通过层序剖面结构、体系域叠加样式和相带组合的沉积响应记录,分析这些记录特征的时空变化规律来有效地揭示盆地沉积充填过程。具体以反映盆地整体特性的构造-层序(二级层序)为基础,以反映盆地充填格架的层序地层(三级层序)为单元,以反映层序沉积充填过程的层序结构、体系域叠置方式(四级以上层序)和相带分布规律为剖析对象"的技术路线,探讨和实践了中上扬子克拉通盆地海西-印支期沉积层序充填过程,剖析典型盆地的充填特征,与分阶段建立沉积演化模式。研究认为,中上扬子克拉通海西-印支期与加里东期的相似性是均由克拉通内和克拉通边缘两大沉积域组成,经历了克拉通边缘伸展和由伸展到挤压的2个盆地演化阶段,差异性是该期盆地类型与演化分异明显。典型盆地沉积充填特征表明,不同时期盆地充填特征的差异性决定于沉积充填控制因素的变化,各因素的控制作用因时因地而异。构造-层序充填过程的控制因素复杂多样,包括同沉积断裂、古地理格局、古隆起、碳酸盐生产率变化、相对海平面变化、基底构造特征和构造运动等,各种控制因素通过对层序沉积充填的边界条件、古地理背景、沉积环境、物源性质、层序结构和叠加样式等方面的影响来控制层序的发育,而且是造成沉积层序充填特征差异性的根本原因。各阶段沉积模式具有个性鲜明的充填背景、沉积建造类型、相带展布规律、演化过程和控制因素。海西-印支期中上扬子克拉通台地内保持隆坳相间,台缘以台盆相间为特征,优质储层发育于台地内和台缘高能礁滩环境,台内滞留环境和台盆区为有利盖层和烃源岩发育区。

昆秦接合部海西期苦海—赛什塘分支洋的存在及其证据

在昆仑与秦岭造山带东、西接合部位 ,通过详细填图与解剖发现海西期在苦海—赛什塘一带 ,存在一条NEE向与东昆仑布青山—阿尼玛卿洋相连通的分支小洋盆 ,称为苦海—赛什塘分支洋 .晚泥盆世—石炭纪是苦海—赛什塘分支洋扩张时期 ,出现大量似洋壳物质 ,雪穷、错扎玛洋脊型蛇绿岩是该时期的物质表现 ,蛇绿岩组合中的40 Ar/ 3 9Ar年龄 (36 8.6± 1.4 )Ma ,与布青山 -阿尼玛卿洋扩张洋盆形成时期相吻合 .扩张形成的苦海—赛什塘分支洋蛇绿岩组合显示属于发育不成熟的有限小洋盆 .扩张作用表现之一是大量记录在裂解块体岩片和结晶基底中的构造热事件 ,如龙通斜长角闪岩、角闪石低温坪年龄 (35 8.9± 3.2 )Ma(40 Ar/ 3 9Ar)、羊曲云母石英构造片岩黑云母坪年龄 (387.3± 2 .3)Ma(40 Ar/ 3 9Ar)、苦海黑云斜长片麻岩等时线年龄 (336± 2 .2 )Ma(Rb -Sr)、扎那合惹斜长角闪岩角闪石低温坪年龄 (376 .9± 0 .9)Ma(40 Ar/ 3 9Ar)等反映了裂解时限 ;其次是侵入裂解块体岩片中的拉龙洼辉绿岩墙群辉石3 9Ar/ 40 Ar坪年龄为 398.4Ma,反映初始扩张始于泥盆纪 .早-中二叠世分支洋发展进入俯冲消减阶段 ,早期沿柴达木微陆块东南缘形成了早二叠世岛弧火山岩 (2 6 4Ma)和纳木龙俯冲型花岗岩 (2 6 7Ma) ,晚期随着俯冲作用加?

内蒙古狼山造山带构造演化与成矿响应

狼山造山带位于华北地台北缘西段,它经历了新太古代和古元古代结晶基底形成与变形、中元古代被动陆缘裂陷槽裂解→沉积→闭合、新元古代晚期开始的活动陆缘、海西期→中生代以来的挤压造山并伴有大量中酸性岩浆侵入的漫长构造演化与发展过程。该造山带有丰富的锌、铅、铜、铁、金等矿产资源,矿床(化)类型、矿床规模与时空分布规律都与其成矿地质背景、构造演化有密切的耦合关系,在不同构造演化阶段有不同的矿床形成:在新太古代主要形成了海底火山环境热水沉积条带状铁矿、在中元古代主要形成了与被动陆缘裂解过程相关的海底啧流.沉积铅锌铜铁硫化物矿床、而在海西期—中生代以来挤压造山过程中的岩浆热液活动,既形成了中小型的斑岩型铜金矿床、又对中元古代等先成的喷流-沉积矿床产生了明显的改造和叠加成矿作用。东升庙、炭窑口和霍各乞矿床的部分铜矿是造山过程中叠加成矿的结果。