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1.
This report proposes a plate tectonic model that can explain the Early/Middle Ordovician erosional unconformity observed along much of the western margin of the Appalachian orogen. In order for the model to apply, the Taconic allochthons must represent an outer arc (accretionary wedge) and the related subduction zone and Benioff zone must have dipped east (this report reviews the evidence for these assumptions). If these suppositions are correct, then the observed unconformity may have resulted from upwarp along a peripheral bulge (which occurs seaward of present-day oceanic trenches) as the Ordovician continental margin drifted east into the trench. Theoretical calculations show that the amount of uplift experienced by a continental plate over a peripheral bulge is on the order of the amount of uplift observed on the unconformity in Newfoundland. Furthermore, the sequence of events in Taconic times along the western margin of the Appalachian orogen supports the hypothesis that the paleocontinental margin drifted east over a peripheral bulge and on into the trench. The Ordovician shallow-water carbonate bank on the continental margin of the North American plate was uplifted (peripheral bulge) and then rapidly down-dropped to abyssal depths (continental margin entering trench) where it was first covered by flysch and then structurally overlain by the Taconic allochthons (continental margin underthrusting the outer arc). The present western boundary of the maximum relief on the unconformity would delineate the trend and approximate position of the bulge when the craton jammed the subduction zone and ceased convergence with the island arc (in Caradocian times).  相似文献   

2.
Placing ore formation within the overall tectonic framework of an evolving orogenic system provides important constraints for the development of plate tectonic models. Distinct metallogenic associations across the Palaeozoic Lachlan Orogen in SE Australia are interpreted to be the manifestation of interactions between several microplates and three accretionary complexes in an oceanic back-arc setting. In the Ordovician, significant orogenic gold deposits formed within a developing accretionary wedge along the Pacific margin of Gondwana. At the same time, major porphyry Cu-Au systems formed in an oceanic island arc outboard of an evolved magmatic arc that, in turn, gave rise to granite-related Sn-W deposits in the Early Silurian. During the ongoing evolution of the orogen in the Late Silurian to Early Devonian, sediment-hosted Cu-Au and Pb-Zn deposits formed in short-lived intra-arc basins, whereas a developing fore-arc system provided the conditions for the formation of several volcanogenic massive sulphide deposits. Inversion of these basins and accretion to the Australian continental margin triggered another pulse of orogenic gold mineralisation during the final consolidation of the orogenic belt in the Middle to Late Devonian.  相似文献   

3.
The tectonic activities during late Archaean-earlyProterozoic is the crisis during the process of crustevolution. The tectonic kinematical mode and dynamicprocess of metamorphic complexes formed is the keyproblem in geosciences[1—7], related to many importantgeological events, such as the substitute of dynamicalsystems and the corresponding relationship betweendeep crust-mantle structure and upper regional stressfield. The predecessors have made a great deal ofstudy on this topic and achieved…  相似文献   

4.
Detailed geologic mapping, petrography, and major and trace-element analyses of Proterozoic rocks from the Greenwood Lake Quadrangle, New York are compared with chemical analyses and stratigraphic information compiled for the entire Reading Prong. A persistent regional stratigraphy is evident in the mapped area whose geochemistry indicates protoliths consistent with a back-arc marginal basin sequence. The proposed marginal basin may have been floored by an older sialic basement and overlain by a basin-fill sequence consisting of a basal tholeiitic basalt, basic to intermediate volcanic or volcaniclastic rocks and carbonate sediments, a bimodal calc-alkaline volcanic sequence, and finally volcaniclastic, marine, and continental sediments. The presence of high-chlorine biotite and scapolite may indicate circulation of brine fluids or the presence of evaporite layers in the sequence. Abundant, stratabound magnetite deposits with a geologic setting very unlike that of cratonic, Proterozoic banded-iron formations are found throughout the proposed basin sequence. Associated with many of the magnetite deposits is unusual uranium and rare-earth element mineralization. It is proposed here that these deposits formed in an exhalative, volcanogenic, depositional environment within an extensional back-arc marginal basin. Such a tectonic setting is consistent with interpretations of protoliths in other portions of the Reading Prong, the Central Metasedimentary Belt of the Canadian Grenville Province, and recent interpretation of the origin of the Franklin lead-zinc deposits, suggesting a more cohesive evolving arc/back-arc tectonic model for the entire Proterozoic margin of the north-eastern portion of the North American craton.  相似文献   

5.
Aerogeophysical and seismological data from a geophysical survey in the interior of East Antarctica were used to develop a conceptual tectonic model for the Lake Vostok region. The model is constrained using three independent data sets: magnetic, seismic, and gravimetric. A distinct change in the aeromagnetic anomaly character across Lake Vostok defines a crustal boundary. Depth to magnetic basement estimates image a 400-km-wide and more than 10-km-deep sedimentary basin west of the lake. Analysis of teleseismic earthquakes suggests a relatively thin crust beneath Lake Vostok consistent with predictions from kinematic and flexural gravity modelling. Magnetic, gravity, and subglacial topography data reveal a tectonic boundary within East Antarctica. Based on our kinematic and flexural gravity modelling, this tectonic boundary appears to be the result of thrust sheet emplacement onto an earlier passive continental margin. No data presently exist to date directly either the timing of passive margin formation or the subsequent shortening phase. The preserved thrust sheet thickness is related to the thickness of the passive margin crust. Because a significant amount of time is required to erode the thrust sheet topography, we suggest that these tectonic events are Proterozoic in age. Minor normal reactivation of the thrust sheet offers a simple mechanism to explain the formation of the Lake Vostok Basin. A low level of seismicity exists in the vicinity of this tectonic boundary. The existence of a crustal boundary in the Antarctic interior provides new constraints on the Proterozoic architecture of the East Antarctic craton.  相似文献   

6.
Abstract A series of paleogeographic maps of the Japanese Islands, from their birth at ca 750–700 Ma to the present, is newly compiled from the viewpoint of plate tectonics. This series consists of 20 maps that cover all of the major events in the geotectonic evolution of Japan. These include the birth of Japan at the rifted continental margin of the Yangtze craton ( ca 750-700 Ma), the tectonic inversion of the continental margin from passive to active ( ca 500 Ma), the Paleozoic accretionary growth incorporating fragments from seamounts and oceanic plateaux ( ca 480-250 Ma), the collision between Sino-Korea and Yangtze (250–210 Ma), the Mesozoic to Cenozoic accretionary growth (210 Ma-present) including the formation of the Cretaceous paired metamorphic belts (90 Ma), and the Miocene back-arc opening of the Japan Sea that separated Japan as an island arc (25-15 Ma).  相似文献   

7.
Ion microprobe zircon ages, a Nd model age and RbSr whole-rock dates are reported from the high-grade gneiss terrain at Sabaloka on the River Nile north of Khartoum, formally considered to be part of the Archaean/early Proterozoic Nile craton. The granulites, which are of both sedimentary and igneous derivation, occur as remnants in migmatites. Detrital zircon ages range from ≈ 1000 to ≈ 2650 Ma and prove the existence of Archaean to late Proterozoic continental crust in the sedimentary source region. The Nd model age for one sedimentary granulite is between 1.26 (TCHUR) and 1.70 (TDM) Ga and provides a mean crustal residence age for the sedimentary precursor. Igneous zircons in enderbitic gneiss crystallized at 719 ± 81 Ma ago, an age that also corresponds to severe Pb loss in the detrital zircons and which probably reflects the granulite event at Sabaloka. The RbSr data indicate isotopic homogenization at about 700 Ma ago in the granulites and severe post-granulite disturbance at ≈ 570 Ma in the migmatites. We associate this disturbance with hydration, retrograde metamorphism and anatexis that produced undeformed granites ≈ 540 Ma ago. The ≈ 700 Ma granulite event at Sabaloka suggests that this part of the Sudan belongs to the Pan-African Mozambique belt while the ancient Nile craton lay farther west. The gneisses studied here may represent the infrastructure of the ancient African continental margin onto which the juvenile arc assemblage of the Arabian-Nubian shield was accreted during intense horizontal shortening and crustal interstacking of a major collision event.  相似文献   

8.
Terrane analysis and accretion in North-East Asia   总被引：2，自引：0，他引：2  
Abstract A terrane map of North-East Asia at 1:5 000 000 scale has been compiled. The map shows terranes of different types and ages accreted to the North-Asian craton in the Mesozoic–Cenozoic, sub-and superterranes, together with post-amalgamation and post-accretion assemblages. The great Kolyma-Omolon superterrane adjoins the north-east craton margin. It is composed of large angular terranes of continental affinity: craton fragments and fragments of the passive continental margin of Siberia, and island arc, oceanic and turbidite terranes that are unconformably overlain by shallow marine Middle-Upper Jurassic deposits. The superterrane resulted from a long subduction of the Paleo-Pacific oceanic crust beneath the Alazeya arc. Its south-west boundary is defined by the Late Jurassic Uyandina-Yasachnaya marginal volcanic arc which was brought about by subduction of the oceanic crust that separated the superterrane from Siberia. According to paleomagnetic evidence the width of the basin is estimated to be 1500–2000 km. Accretion of the superterrane to Siberia is dated to the late Late Jurassic-Neocomian. The north-east superterrane boundary is defined by the Lyakhov-South Anyui suture which extends across southern Chukotka up to Alaska. Collision of the superterrane with the Chukotka shelf terrane is dated to the middle of the Cretaceous. The Okhotsk-Chukotka belt, composed of Albian-Late Cretaceous undeformed continental volcan-ites, defines the Cretaceous margin of North Asia. Terranes eastward of the belt are mainly of oceanic affinity: island arc upon oceanic crust, accretion wedge and turbidite terranes, as well as cratonic terranes and fragments of magmatic arcs on the continental crust and metamorphic terranes of unclear origin and age. The time of their accretion is constrained by post-accretionary volcanic belts that extend parallel to the Okhotsk-Chukotka belt but are displaced to the east: the Maastrichtian-Miocene Kamchatka-Koryak belt and the Eocene-Quaternary Central Kamchatka belt which mark active margins of the continent of corresponding ages.  相似文献   

9.
扬子板块东北缘中元古代的大地构造划分   总被引：1，自引：0，他引：1  
扬子板块东北缘存在四条主要的中元古代变质带,自南向北依次为江南变质带、沿江变质带、云台一张八岭变质带和连云港一泗阳变质带。它们分别为中元古代的古弧后盆地、火山岛弧、裂谷及弧前盆地,扬子板块东北缘中元古代为活动大陆边缘构造体系。苏（北）胶（南）变质造山带应解体,其中一部分属扬子大陆边缘体系。  相似文献   

10.
Samples were systematically collected from metamorphic basic volcanic rocks in the Jiehekou and Xiyupi areas on both sides of the Lüliang Mountains, Shanxi Province and analyzed for their major elements, trace elements and rare earth elements (REE). The geochemical characteristics of their major, trace and rare-earth elements indicated that the metamorphic basic volcanic rocks in this area were emplaced in the tectonic environment like a modern continental rift. Sm-Nd and Rb-Sr isotope chronological studies demonstrated that the Jiehekou Group metamorphic basic volcanic rocks were formed during the 2600-Ma crust/mantle differentiation event, and were transformed by granulite facies metamorphism during the late Neo-Archaean period (2500 Ma ±), making the Sm-Nd systematics of the rocks reset. During the late Paleoproterozoic period (1800 Ma ±) the Rb-Sr systematics of the rocks were disturbed again in response to the Lüliang movement. Since the extent of disturbance was so weak that the Sm-Nd systematics was not affected, the age of 1600 Ma ± obtained from this area seems to be related to local magmatic activities within the craton. Research results lend no support to the idea that the Lüliang Group was formed during the Archaean. Instead, it should be formed during the Proterozoic.  相似文献   

11.
New chemical and isotopic data permit the recognition of a cryptic suture zone between two Archaean continental masses within the Nagssugtoqidian mobile belt of West Greenland. This discovery has important implications for Precambrian crustal evolution: suture zones may not always be identifiable from geological field observations, with the consequence that mobile belts in which undetected sutures exist may be mis-identified as ensialic, and thought to require special non-plate tectonic models to account for their development.The Nagssugtoqidian belt consists mainly of Archaean gneisses reworked during the Proterozoic, with metamorphic grade and degree of isotopic disturbance increasing towards the centre of the belt. At the centre of the belt the Nagssugtoqidian includes metasediments and calc-alkaline volcanic and plutonic rocks of Proterozoic age, almost always strongly deformed and metamorphosed. From isotopic evidence (Sri ca. 0.703; model μ1 values ca. 8.0; initial εNd ca. 0) it is clear that the Proterozoic igneous rocks do not include any significant contributions derived from the Archaean crust, and the chemistry of the rocks, together with the isotope data, suggests that they were formed at a destructive plate margin. The Proterozoic rocks are found in a narrow zone (up to 30 km wide) between the Archaean gneisses to the north and south of Nordre Strømfjord, and are interpreted as reflecting the existence of a suture between two Archaean continental blocks. Zircon UPb data and other isotope evidence show that subduction started before ca. 1920 Ma ago, and lasted until ca. 1850 Ma when collision occurred, with consequent crustal thickening, high-grade metamorphism and local anatexis. Given the time-span for the operation of subduction, the existence of a wide Nagssugtoqidian ocean can be inferred, even for slow rates of plate motion.The Proterozoic and Archaean gneisses in the Nagssugtoqidian belt are very similar lithologically and chemically, and it has only been possible to distinguish between them using isotopic criteria. Suture zones of this kind are very difficult to detect, and may be present elsewhere within the reworked Archaean terrains of northern Greenland and Canada.  相似文献   

12.
Crustal shortening of Southwest Japan in the Late Miocene   总被引：5，自引：0，他引：5  
Abstract Tectonic deformation of an island arc is interpreted on the basis of geophysical data. Extensive reflection seismic, gravity, geomagnetic data around the back-arc region of Southwest Japan delineate east-west to northeast-southwest folding, and imply conspicuous compression on the southern margin of the Sea of Japan. Because geological data of exploration boreholes indicate that the coinpressive regime was dominant in the late Miocene, the tectonic event seems to be linked with coeval resumption of subduction of the Philippine Sea Plate. Strong coupling of the young buoyant oceanic plate brought about north-south shortening of the overriding continental lithosphere, and left wrench deformation at the southwestern corner of the Sea of Japan. Amount of shortening for the back-arc shelf and mountainous ranges of Southwest Japan is estimated to be ca 10 km, adopting a uniform ratio of shortening (0.944) since the Miocene determined on the shelf from depth-converted seismic profiles. Along the western side of a bend of boundary between the Eurasian Plate and Philippine Sea Plate, the middle Miocene and younger sediments upon the back-arc shelf are much less deformed than the northern equivalents, and the fore-arc Miocene strata are deformed by left wrenching, facts which are indicative of northerly initial convergence of the Philippine Sea Plate at the end of Miocene and crustal decoupling on the west of Kyushu Island.  相似文献   

13.
A broad zone of dominantly subaerial silicic volcanism associated with regional extensional faulting developed in southern South America during the Middle Jurassic, contemporaneously with the initiation of plutonism along the present Pacific continental margin. Stratigraphic variations observed in cross sections through the silicic Jurassic volcanics along the Pacific margin of southernmost South America indicate that this region of the rift zone developed as volcanism continued during faulting, subsidence and marine innundation. A deep, fault-bounded submarine trough formed near the Pacific margin of the southern part of the volcano-tectonic rift zone during the Late Jurassic. Tholeiitic magma intruded within the trough formed the mafic portion of the floor of this down-faulted basin. During the Early Cretaceous this basin separated an active calc-alkaline volcanic arc, founded on a sliver of continental crust, from the then volcanically quiescent South American continent. Geochemical data suggest that the Jurassic silicic volcanics along the Pacific margin of the volcano-tectonic rift zone were derived by crustal anatexis. Mafic lavas and sills which occur within the silicic volcanics have geochemical affinities with both the tholeiitic basalts forming the ophiolitic lenses which are the remnants of the mafic part of the back-arc basin floor, and also the calc-alkaline rocks of the adjacent Patagonian batholith and their flanking lavas which represent the eroded late Mesozoic calc-alkaline volcanic arc. The source of these tholeiitic and calc-alkaline igneous rocks was partially melted upper mantle material. The igneous and tectonic processes responsible for the development of the volcano-tectonic rift zone and the subsequent back-arc basin are attributed to diapirism in the upper mantle beneath southern South America. The tectonic setting and sequence of igneous and tectonic events suggest that diapirism may have been initiated in response to subduction.  相似文献   

14.
Cretaceous episodic growth of the Japanese Islands   总被引：1，自引：0，他引：1  
G. Kimura 《Island Arc》1997,6(1):52-68
Abstract The Japanese Islands formed rapidly in situ along the eastern Asian continental margin in the Cretaceous due to both tectonic and magmatic processes. In the Early Cretaceous, huge oceanic plateaus created by the mid-Panthalassa super plume accreted with the continental margin. This tectonic interaction of oceanic plateau with continental crust is one of the significant tectonic processes responsible for continental growth in subduction zones. In the Japanese Islands, Late Cretaceous-Early Paleogene continental growth is much more episodic and drastic. At this time the continental margin uplifted regionally, and intra-continent collision tectonics took place in the northern part of the Asian continent. The uplifting event appears to have been caused by the subduction of very young oceanic crust (i.e. the Izanagi-Kula Plate) along the continental margin. Magmatism was also very active, and melting of the young oceanic slab appears to have resulted in ubiquitous plutons in the continental margin. Regional uplift of the continental margin and intra-continent collision tectonics promoted erosion of the uplifted area, and a large amount of terrigenous sediment was abruptly supplied to the trench. As a result of the rapid supply of terrigenous detritus, the accretionary complexes (the Hidaka Belt in Hokkaido and the Shimanto Belt in Southwest Japan) grew rapidly in the subduction zone. The rapid growth of the accretionary complexes and the subduction of very young, buoyant oceanic crust caused the extrusion of a high-P/T metamorphic wedge from the deep levels of the subduction zone. Episodic growth of the Late Cretaceous Japanese Islands suggests that subduction of very young oceanic crust and/or ridge subduction are very significant for the formation of new continental crust in subduction zones.  相似文献   

15.
The exposed elements of the Lower Proterozoic orogenic belts of the Halls Creek sub-province, Northern Australia, lie in fault zones which have suffered repeated tectonic activity at various times through the Proterozoic and Phanerozoic. The Halls Creek and King Leopold orogenic domains subtend an angle of 80° and are characterized by linear late tectonic batholithic complexes several hundred kilometres long but only a few tens of kilometres wide, reminiscent of those in Phanerozoic Cordilleran orogenies. The associated superposed folding and high temperature metamorphism are more akin to those in Phanerozoic collision orogenies.The sub-province is analyzed in the wider context of the North Australian orogenic province which was deformed, metamorphosed and intruded by granitic plutons approximately 1900-1800 Ma ago. In this province the Archaen basement was extended and broken into a mosaic of blocks, some of which (now largely concealed by younger Kimberley and McArthur basin sediments) retained a more positive character and fed sediment to intervening regions (such as the Pine Creek Geosyncline) which suffered greater extension and subsidence, but which retained a thinned Archaean basement.The Halls Creek Group was deposited in a trough to the south-east of the Kimberley island continent, and deposition was probably broadly contemporaneous with, and continuous with, that in the Pine Creek geosyncline. A volcanic—fine grained clastic—carbonate phase of marine deposition, following basin formation, is represented by the Biscay Formation. During the later phase of basin evolution widespread flysch facies (Olympio Formation), partly derived from the island continent, was deposited and is now preserved in low grade zones on both sides of the main belt of high strain and upper amphibolite to lower granulite facies metamorphism which displays recumbent folding and nappe tectonics with fold axes oblique to the major faults.No island arc compex or paired metamorphic belts are present in the orogenic belts, and it is concluded that the lithospheric extension and subsequent convergence did not involve the generation of oceanic crust or B-subduction.In the Halls Creek domain vergence is south-easterly across all zones and is related to oblique convergence leading to limited A-subduction of the basinal area in the south-east beneath the island continent to the north-west, accompanied by left-lateral strike-slip or transform fault movements on the north-trending major faults. The convergence generated the associated high temperature metamorphism and plutonism on the leading edge of the lower plate.A phase of upright folding (with trends varying continuously form E-W in the King Leopold belt to NNE-SSW in the Halls Creek belt) intervenes between the main recumbent deformation and metamorphism (ca 1920 Ma ago) and the emplacement of the late tectonic granite batholiths (ca 1840 Ma ago) which are fault controlled.The province represents a distinctive type of linear Proterozoic ensialic orogeny, not explicitly identified previously, and it needs to be distinguished both from true collision orogenies of the Phanerozoic, involving a Wilson Cycle, and from the areally extensive Proterozoic orogenies with which it is associated. Its essential characteristics are due to convergence between a small continent and an ‘oceanic’ area underlain by thin continental crust, resulting in limited A-subduction of the latter prior to crustal shortening.  相似文献   

16.
巴布亚新几内亚在大地构造位置上位于欧亚板块、印度-澳大利亚板块和太平洋板块的结合部位.本文介绍了自晚白垩世以来巴布亚新几内亚经历的复杂地质构造演化过程,不同板块间的汇聚、碰撞、俯冲和拆离、扩张等地质作用形成了以区内南部克拉通、中部褶皱带及北部岛弧带为特点的地质构造单元,在区内形成了具有活动大陆边缘特色的成矿系统,对寻找以斑岩型和浅成低温热液型铜金矿、红土型镍矿为主要成矿类型具有重要意义.  相似文献   

17.
秦岭造山带与其南北两侧华北克拉通和扬子克拉通属三大构造单元,不论其各构造单元体还是其界带构造均甚为复杂,并受到多期次构造运动的制约,形成了大陆内部特异的造山过程.尽管在这一地域曾做过大量的地表地质工作和一些相关的地球物理工作,但对其壳、幔精细结构、深层动力过程,特别是同步穿越华北克拉通、秦岭-大巴造山带和扬子克拉通系统的耦合研究甚少.为了研究和探索该地域的壳、幔精细速度结构和其形成的深层过程,专门布置了一条北起榆林,向南经咸阳、宁陕直抵涪陵长达1000 km的高精度地震宽角反射、折射波场探测剖面.通过剖面辖区高分辨率的数据采集,数据处理、反演和壳、幔层、块精细速度结构,发现剖面辖区深部壳、幔结构存在特异的速度和结构变化,并厘定了一系列的新认识.研究结果表明:(1)秦岭—大巴造山带具有同一基底,其形成乃为结晶基底隆升所致,即它的形成仅涉及到上地壳的受力变形和空间状态.造山带与其南、北两侧的前陆盆地为陆内造山过程中同一深层过程的产物,但其沉积速率和形态却不相同.华北克拉通与秦岭造山带之间前陆盆地Bfc拉张为该区Moho界面的局部隆升所致.(2)首次提出了沿1000 km长剖面连续的沉积建造、结晶基底、上地壳、下地壳和上地幔顶部的层、块速度结构和各界面的起伏变化与空间状态.基于地震波边界场响应厘定了华北克拉通、秦岭—大巴造山带和扬子克拉通的分区界带.论述了三大构造单元各自的内部结构和其相邻界域的速度变化特征.(3)该区大陆内部速度结构和不同类型断裂分布及层序在华北克拉通、秦岭—大巴造山带、扬子克拉通三大块体地域存在显著差异.不同规模、层次与产状的断裂分布反映出它们在变形行为和机制上及所受构造运动的制约上均存在明显的差异.  相似文献   

18.
Paleomagnetic studies of rocks from the Bonin and Mariana Island arcs indicate that these island arcs have undergone substantial rotation and northward translation since their formation 40 to 45 Ma. These rotations are inconsistent with existing models of marginal basin and island arc formation. The data presently available suggest to us that the Mariana and Bonin island arcs rotated as one tectonic element at the margin of the Philippine Sea and Pacific plate. These observations demonstrate that large vertical axis rotations are present in the island arc environment, prior to any interaction with a continental landmass. Since many circum-Pacific marginal terranes have been assigned island arc origins, these pre-accretion rotations should be considered when interpreting paleomagnetic results for possible microplate reconstructions. Knowledge of the structural and rotational styles of oceanic pre-accretionary deformations may prove useful for separating these pre-accretion effects from those imposed by the accretionary process in future studies aimed at deciphering the geologic history of island arc marginal terranes.  相似文献   

19.
Lithosphere types in North China: Evidence from geology and geophysics   总被引：3，自引：0，他引：3  
Deep-seated materials from lithosphere are the ba- sic parameters and the foundation for geodynamic and continental dynamic studies. Division of lithosphere types and their deep-seated materials and structure can provide important evidence in interpreting the com- plex phenomena derived from the processes of forma- tion and evolution of continents, in evaluating the mineral resource potential, in predicting geological disasters and in the research of the continental dy- namic process. Huge lit…  相似文献   

20.
华南岩石层与大陆动力学   总被引：5，自引：1，他引：5       下载免费PDF全文
华南大陆记录和保存了自太古代至今大陆生长层完整的历史过程.以杨子克拉通为核心，地壳不断向东南生长，古扬子块前寒武系以灰色片麻岩、古元古代科马提岩绿岩、新元古代蛇绿岩、绿岩为特征，为相对稳定高速高阻冷的残存地幔“残烃柱”；而沿海一带火成岩以中、新生代壳－幔混合源火山－侵入杂岩、碱性花岗岩和正长岩带以及不同类型的玄武岩类为特征，为相对活动低速高导热的超地幔柱．巨型裂解构造是物质热传输的主要形式，地幔柱迁移是华南大陆构造演化的原动力．  相似文献   

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