共查询到20条相似文献，搜索用时 31 毫秒
1.
《International Geology Review》2012,54(2):172-191
The Divrigi and Kuluncak ophiolitic mélanges are located in central Anatolia in the Tauride ophiolite belt. The stratigraphic sequence in the Divrigi ophiolitic mélange includes, from bottom to top, the Upper Jurassic-Lower Cretaceous Akdag limestone, Upper Cretaceous Çalti ultramafic rocks, and the Curek listwaenite. The Divrigi ophiolitic mélange is intruded by the Late Cretaceous-Eocene Murmano pluton. The above stratigraphic sequence is followed by the Eocene-Paleocene Ekinbasi metasomatite and the Quaternary Kilise Formation. The oldest sequence of rocks in Kuluncak ophiolitic mélange in the GuvenÇ area is the Karadere serpentine/ultramafic body overlain successively by the Kurtali gabbro, Gundegcikdere radiolarite, the GuvenÇ listwaenites, and the Buldudere Formation. All of these units are Late Cretaceous in age. The Karamagra siderite deposit in the Hekimhan area probably was formed in the Lower Cretaceous at the contact between Çalti ultramafic rocks and the Buldudere Formation. The Kuluncak ophiolitic mélange was intruded by a subvolcanic trachyte in the Late Cretaceous. The Eocene-Paleocene Konukdere metasomatite, the Miocene Yamadag volcanic rocks, and Quaternary slope deposits are late in the stratigraphic sequence in the GuvenÇ area. The Kuluncak ophiolitic mélange in the Karakuz area is similar to that at GuvenÇ; however, gabbro, radiolarite, and Miocene volcanic rocks are not present. The Miocene is represented by the Ciritbelen Formation at Karakuz and the Karakuz iron deposit is hosted by a Late Cretaceous subvolcanic trachyte. The rareearth and trace-element concentration of serpentinite in the Divrigi and Kuluncak ophiolitic mélanges indicate that all of the ultramafics and their alteration products were derived from a MORB, which was depleted in certain elements and oxides. The results expressed in this study support the idea that the Divrigi and Kuluncak ophiolitic mélanges within the Tauride ophiolite belt originated from Northern Tauride oceanic lithosphere (Poisson, 1986), instead of a northern branch of Neo-Tethys (Sengor and Yilmaz, 1981). 相似文献
2.
蛇绿岩作为残留洋壳的良好记录,对于研究古板块构造及其演化具有重要意义。新发现的吐尔库班套蛇绿混杂岩位于新疆阿尔泰布尔津南部,主要由超镁铁岩、辉长岩、辉绿岩、玄武岩、复理石建造等构成。其中辉长岩和片麻状花岗岩的锆石U Pb年龄在363～355 Ma,指示蛇绿岩的形成、洋壳俯冲时代在晚泥盆世晚期。岩石地球化学特征表明,该蛇绿岩套的镁铁超镁铁岩和玄武岩属低碱、低钛、富镁的拉斑玄武岩系列,具有较典型的幔源岩石特征,玄武岩形成于类似洋中脊的构造环境。混杂岩带中的片麻状花岗岩属于钠质的低钾岩石系列,形成于火山弧或同碰撞构造环境,亦为洋壳俯冲的结果。吐尔库班套蛇绿岩与科克森套、乔夏哈拉、布尔根蛇绿岩一起构成了沿额尔齐斯分布的蛇绿混杂岩带,构成了分割西伯利亚板块和哈萨克斯坦-准噶尔板块的斋桑-科克森套-南蒙古缝合带。 相似文献
3.
Koushick Sen Souvik Das Barun K. Mukherjee Koushik Sen 《International Journal of Earth Sciences》2013,102(7):2033-2042
Zildat Ophiolitic Mélange (ZOM) of the Indus Suture Zone, Himalaya, represents tectonic blocks of the fragmented oceanic metasediments and ophiolite remnants. The ZOM is sandwiched between the Zildat fault adjacent to a gneissic dome known as Tso Morari Crystalline (TMC) and thin sliver of an ophiolite called as the Nidar Ophiolitic Complex. The ZOM contain chaotic low-density lithologies of metamorphosed oceanic sediments and hydrated mantle rocks, in which carbonates are present as mega-clasts ranging from 100 meters to few centimeters in size. In this work, calcite microstructures, fluid inclusion petrography and stable isotope analyses of carbonates were carried out to envisage the emplacement history of the ZOM. Calcite microstructure varies with decreasing temperature and increasing intensity of deformation. Intense shearing is seen at the marginal part of the mélange near Zildat fault. These observations are consistent with the mélange as a tectonically dismembered block, formed at a plate boundary in convergent setup. The δ18O and δ13C isotope values of carbonates show bimodal nature from deeper (interior) to the shallower (marginal, near the Zildat fault) part of the mélange. Carbonate blocks from deeper part of the mélange reflect marine isotopic signature with limited fluid–rock interaction, which later on provide a mixing zone of oceanic metasediments and/or hydrated ultramafic rocks. Carbonates at shallower depths of the mélange show dominance of syn-deformation hydrous fluids, and this has later been modified by metamorphism of the adjacent TMC gneisses. Above observations reveal that the mélange was emplaced over the subducting Indian plate and later on synchronously deformed with the TMC gneissic dome. 相似文献
4.
甘肃北山火石山地区早古生代蛇绿混杂岩的发现及其地质意义 总被引：6，自引：1，他引：6
在甘肃北山火石山地区新发现了蛇绿混杂岩,该混杂岩由蛇绿岩岩块和混杂基质组成。蛇绿岩块有纯橄岩、辉石橄榄岩、辉石岩、辉长岩、玄武岩及硅质岩等。基质为志留系中上统公婆泉群,主要是一套变凝灰质砂岩夹碳酸盐岩和少量安山岩。野外调查及室内鉴定结果显示蛇绿岩岩块和基质遭受了较强的变质变形。火石山蛇绿混杂岩位于红柳河、牛圈子蛇绿岩之间,且该蛇绿岩地球化学特征显示其同红柳河蛇绿岩相似,因此认为红柳河—牛圈子蛇绿混杂岩是通过火石山相连接。火石山蛇绿混杂岩的发现对研究该带洋陆时空演化提供了新的线索,对北山古生代构造背景研究具有重要意义。 相似文献
5.
东昆仑可支塔格蛇绿混杂岩的地质地球化学特征 总被引：1，自引：0，他引：1
东昆仑可支塔格蛇绿混杂岩属于木孜塔格-鲸鱼湖大断裂的西延部分,主要由辉橄岩、辉长岩、闪长岩、斜长花岗岩、辉绿岩、玄武岩及硅质岩等组成,形成时代为早石炭世。为构造强烈破坏的蛇绿混杂岩,形成于俯冲带环境,属SSZ型蛇绿岩。其中辉橄岩以相对低SiO2、TiO2、Al2O3和CaO、高MgO为特征,贫有色金属成矿元素,富集相容元素Cr、Ni、Co。稀土总量低,接近于球粒陨石稀土元素总量,以LREE略富集为特征。闪长岩SiO2、K2O含量较低,MgO、CaO、Na2O较高,稀土总量高,∑REE为90.95μg/g,LREE富集。斜长花岗岩SiO269.8%,Na2O>K2O,K2O/Na2O为0.78,A/CNK为1.68,具有大洋斜长花岗岩的岩石化学特征。闪长岩、斜长花岗岩的微量元素特征相似,表现为大离子亲石元素K、Sr、Rb、Ba相对富集,高场强元素Nb、Ta、Zr、Hf相对亏损。研究表明,辉橄岩来源于亏损的地幔岩,接近于强烈亏损的方辉橄榄岩,而明显不同于结晶分异作用成因的超镁铁质岩石。闪长岩、斜长花岗岩为蛇绿混杂岩的浅色岩组分,是地幔岩浆结晶分异的产物。 相似文献
6.
The Batinah mélange which overlies the late Cretaceous Semail ophiolite in the northern Oman Mountains comprises mostly sedimentary rocks of deep-water facies, alkalic lavas and intrusives, all of continental margin affinities, together with smaller volumes of Semail ophiolitic and metamorphic rocks. Four intergradational textural types of mélange can be recognized. Sheet mélange has large (>1 km) intact sheets either with little intervening matrix or set in other mélange types, and with an organised sheet orientation fabric. Slab mélange is finer textured (>100 m) and more disrupted. Block mélange has smaller (> m) blocks with some matrix and a weak to random block fabric. Clast mélange is matrix-supported rudite with a weak depositional clast fabric. Structural relationships, particularly the absence of tectonic fabrics, the decreasing strength of fragment fabrics with increasing fragmentation, and the abundance of brittle fragmentation, suggest that these mélange types formed by either gravity-driven sedimentary processes or superficial sliding or thrusting of individual rock slabs.In the slab mélange, long sequences can be pieced together, passing up from Upper Triassic mafic sub-marine extrusives and sediments into radiolarian cherts, hemipelagic and redeposited limestones, and terminating in non-calcareous radiolarities with Mn-deposits of early Cretaceous age. Mafic sills are numerous. These sequences can be matched with sub-ophiolite rocks now exposed in fault corridors through the Semail. These sequences become progressively disrupted upwards in the corridors and can be traced continuously into overlying mélange, which then thins away from the corridors.We argue that, during late Cretaceous emplacement over the Arabian margin, active fault corridors split the Semail slab and acted as conduits up which sub-ophiolite rocks were supplied to the ophiolite surface. There the rocks were redisributed by superficial processes. 相似文献
7.
玛依勒蛇绿岩出露于玛依勒蛇绿混杂岩带中,该带位于西准噶尔造山带西南缘,是区内规模较大的一条蛇绿混杂岩带,蛇绿岩中镁铁-超镁铁质岩研究对探讨古亚洲洋古生代构造演化具有重要意义。本文选取玛依勒蛇绿岩中的镁铁-超镁铁质岩进行系统的岩石学、地球化学和年代学研究。结果表明,玛依勒蛇绿混杂岩中超镁铁质岩以富集Al_2O_3、CaO为特征,TiO_2含量与俯冲带之上地幔橄榄岩中含量相当,稀土配分曲线为轻稀土富集型,微量元素受蚀变作用影响,呈现出两种不同的曲线特征。镁铁质岩石可分为两组:I组镁铁质岩具有高MgO、低Al_2O_3,LREE轻微富集,富集大离子亲石元素,亏损Nb、Ta的特征,形成于消减带相关的岛弧环境;Ⅱ组镁铁质岩具有富碱、TiO_2,且呈LREE显著富集的右倾稀土配分曲线特征,富集大离子亲石元素,Nb、Ta正异常特征,代表了洋盆中海山或洋岛的残片。I组镁铁质岩中两个辉长岩岩块的LA-ICP-MS锆石UPb年龄分别为512.1±7.2Ma(MSWD=0.014)和531±12Ma(MSWD=0.17),与巴尔鲁克蛇绿岩、唐巴勒蛇绿岩中镁铁质岩岩块获得的锆石U-Pb年龄相吻合,且这三条蛇绿岩都具有SSZ型蛇绿岩的地球化学特征,可能为不同环境下同一洋盆的演化产物。 相似文献
8.
The Alxa region, located in the southernmost part of Central Asian Orogenic Belt, is a key region for understanding the tectonic processes associated with the closure of the Paleo-Asian Ocean. Issues of late Paleozoic tectonic settings and tectonic unit divisions of the Alxa region still remain controversial. In this study, we report a new ophiolitic mélange named the Tepai ophiolitic mélange in the northern Alxa region, northwest of Alxa Youqi. The tectonic blocks in the Tepai ophiolitic mélange are mainly composed of serpentinized peridotites, serpentinites, mylonitized gabbros, gabbros, basalts, and quartzites, with a matrix comprising highly deformed clastic rocks. A gabbro exhibits a zircon LA-ICP-MS Ue Pb age of278.4 ± 3.3 Ma. Gabbros exhibit high Mg O and compatible element contents, but extremely low TiO_2,totally rare earth element and high field strength element contents. These rocks exhibit light rare earth element depleted patterns, and display enriched in large-ion lithophile elements and depleted in high field strength elements. Boninite-like geochemical data show that they were formed in a subductionrelated environment, and derived from an extremely depleted mantle source infiltrated by subduction-derived fluids and/or melts. The Tepai ophiolitic mélange exhibits similar zircon U-Pb-O isotopic compositions and whole-rock geochemical characteristics to those of the Quagan Qulu ophiolite.Therefore, we propose that the Tepai ophiolitic mélange may have been the western continuation of the Quagan Qulu ophiolite. Our new finding proves the final closure of the Paleo-Asian Ocean might have taken place later than the early Permian. 相似文献
9.
Thungyani N. Ovung Jyotisankar Ray Biswajit Ghosh Debabrata Mandal Pallab Dasgupta Madhuparna Paul 《Journal of the Geological Society of India》2017,90(2):154-158
Serpentinization is pervasive in the ultramafic rocks of Manipur ophiolite belt (MOB), Northeastern India. Electron microprobe data of a serpentinite from the Ukhrul-Nungbi sector of MOB shows Ni-rich serpentine mineral (NiO = 33.4-33.9 wt %, SiO2= 37.55-38.96 wt %, MgO= 14.83-16.89 wt %). The composition and X-ray diffraction pattern characterize this Ni-rich serpentine mineral as népouite which is suggested to be a hydrothermal alteration product of NiO-rich olivine in a fore-arc peridotite. The genesis of this NiO-rich olivine is attributed to the melt-rock interaction in a supra-subduction zone setting. 相似文献
10.
孕灾地质基因是指一定区域所具有的促进地质灾害孕生的内在关键因素。板块构造混杂岩带所处的特殊构造部位决定了其复杂的演化过程和特殊的地质基因。本文在梳理青藏高原构造混杂岩带地质特征的基础上,总结分析了其孕灾地质基因,包括活跃的地质构造、复杂的水热条件、混杂的岩性组合、特殊的蚀变软岩和构造岩溶导水通道等,是引发重大地质灾害和工程地质安全风险的根源。结合典型案例,剖析了构造混杂岩带大型滑坡的成因类型主要有三大类：构造控制型、泥质软岩控制型和蚀变蛇绿岩带控制型,其中蚀变蛇绿岩带是构造混杂岩带最具特色的易滑地质结构,具有典型的地质构造与特殊岩性联合控制特征。构造混杂岩带隧道工程变形破坏主要有塌方、水平收敛、环向收敛、底鼓和错断等五种模式,黏土化蚀变软岩的不良工程特性是制约构造混杂岩带隧道围岩稳定性的重要因素。针对传统的工程地质理论和灾害风险防控技术难以适应构造混杂岩带大规模工程建设面临的挑战,提出了有待深入研究的关键问题和防灾减灾策略。 相似文献
11.
N. Yu. Bragin L. G. Bragina N. Djeri? M. Tolji? 《Stratigraphy and Geological Correlation》2011,19(6):631-640
Blocks of cherty rocks and Aptychus Limestone embedded into ophiolite mélange south of Avala Gora (Serbia) contain radiolarians
of different ages. We distinguished here Late Jurassic (middle Oxfordianearly Tithonian), Middle-Late Jurassic (Bathonian-early
Tithonian), and Middle Triassic (early Ladinian) radiolarian assemblages. The respective stratigraphic data suggest that the
ophiolite mélange was formed after the early Tithonian. 相似文献
12.
阿尔金山北缘冰沟蛇绿混杂岩中辉长岩锆石SHRIMP U-Pb定年及其地质意义 总被引：5，自引：3，他引：2
冰沟蛇绿混杂岩是阿尔金山红柳沟蛇绿混杂岩带的东段部分,岩石组合包括蛇纹岩、方辉橄榄岩、辉石岩和辉长岩等。蛇纹岩具高Mg,Mg/Fe值大于9,低Al、Ca、Na、K为特征,从稀土元素和微量元素特征来看,基性辉长岩和洋壳以及洋中脊玄武岩极为相似,而超基性岩与原始地幔较为接近。辉长岩获得锆石SHRIMP年龄为449.5±10.9Ma。蛇绿混杂岩的围岩为一套巨厚的碎屑岩、火山碎屑岩、火山岩,以及部分碳酸盐岩构成,其中含有具有洋中脊特征的枕状构造玄武岩,以及放射虫硅质岩,放射虫时代为奥陶纪中晚期,与辉长岩的SHRIMP年龄一致。这些证据进一步证实了红柳沟一带存在早古生代洋盆的地质事实。 相似文献
13.
《Chemie der Erde / Geochemistry》2019,79(2):337-346
Rare earth element (REE) and strontium isotope data (87Sr/86Sr) are presented for hydromagnesite and surface waters that were collected from Dujiali Lake in central Qinghai-Tibet Plateau (QTP), China. The goal of this study is to constrain the solute sources of hydromagnesite deposits in Dujiali Lake. All lake waters from the area exhibit a slight LREE enrichment (average [La/Sm]PAAS = 1.36), clear Eu anomalies (average [Eu/Eu*]PAAS = 1.31), and nearly no Ce anomalies. The recharge waters show a flat pattern (average [La/Sm]PAAS = 1.007), clear Eu anomalies (average [Eu/Eu*] PAAS = 1.83), and nearly no Ce anomalies (average [Ce/Ce*]PAAS = 1.016). The REE+Y data of the surface waters indicate the dissolution of ultramafic rock at depth and change in the hydrogeochemical characteristics through fluid-rock interaction. These data also indicate a significant contribution of paleo-groundwater to the formation of hydromagnesite, which most likely acquired REE and Sr signatures from the interaction with ultramafic rocks. The 87Sr/86Sr data provide additional insight into the geochemical evolution of waters of the Dujiali Lake indicating that the source of Sr in the hydromagnesite does not directly derive from surface water and may have been influenced by both Mg-rich hydrothermal fluids and meteoric water. Additionally, speciation modeling predicts that carbonate complexes are the most abundant dissolved REE species in surface water. This study provides new insights into the origins of hydromagnesite deposits in Dujiali Lake, and contributes to the understanding of hydromagnesite formation in similar modern and ancient environments on Earth. 相似文献
14.
This study presents new data on the geochemistry and mineral chemistry of ultramafic and mafic rocks in ophiolits from the
base of the Kumroch segment of the Achayvayam-Valagin paleoarc. The new data enabled us to consider peridotites and the associated
diabases and gabbros enclosed as separated blocks into a serpentinite mélange as a single ophiolite complex formed in a supra-subduction
setting and subsequently disintegrated as a result of nappe formation. The variations identified in the geochemistry and compositions
of rock-forming minerals are shown to be characteristic of the other study ophiolite complexes of Eastern Kamchatka. This
is suggested to reflect spatial-temporal heterogeneity of partial melting during evolution of the Achayvayam-Valagin island
arc. 相似文献
15.
对金沙江缝合带西段青海治多地区的多彩蛇绿混杂岩和当江荣中酸性岛弧火山岩进行了研究,野外地质剖面显示,蛇绿岩主要由辉长岩、堆晶辉长岩和玄武岩组成,缺少地幔橄榄岩单元。通过对蛇绿岩内部细粒辉长岩、基性熔岩的地球化学测试及堆晶辉长岩的LA-ICP-MS锆石U-Pb测年发现,基性熔岩可分为2种类型,即洋岛玄武岩OIB型和MORB-IAT型。前者并非蛇绿岩组分,为构造就位时带入;后者为过渡类型,具有典型洋中脊—岛弧蛇绿岩地球化学特征。辉长岩具有明显的TNT槽等岛弧信号,与类型二均属于蛇绿岩成分。测得的堆晶辉长岩中锆石U-Pb年龄为252.50Ma±0.58Ma(MSWD=0.95),是蛇绿岩的形成年龄。研究认为,多彩蛇绿岩与当江荣火山岩具有成对性关系,结合造山带沟—弧—盆体系构造格局,认为前者形成于岛弧偏海沟的弧前构造背景,是晚二叠世金沙江洋持续俯冲的产物。 相似文献
16.
D. V. Faustino G. P. Yumul J. V. De Jesus C. B. Dimalanta J. C. Aitchison M-F. Zhou 《Australian Journal of Earth Sciences》2013,60(4):571-583
Recent field mapping has refined our understanding of the stratigraphy and geology of southeastern Bohol, which is composed of a Cretaceous basement complex subdivided into three distinct formations. The basal unit, a metamorphic complex named the Alicia Schist, is overthrust by the Cansiwang mélange, which is, in turn, structurally overlain by the Southeast Bohol Ophiolite Complex. The entire basement complex is overlain unconformably by a ～2000 m thick sequence of Lower Miocene to Pleistocene carbonate and clastic sedimentary rocks and igneous units. Newly identified lithostratigraphic units in the area include the Cansiwang mélange, a tectonic mélange interpreted as an accretionary prism, and the Lumbog Volcaniclastic Member of the Lower Miocene Carmen Formation. The Cansiwang mélange is sandwiched between the ophiolite and the metamorphic complex, suggesting that the Alicia Schist was not formed in response to emplacement of the Southeast Bohol Ophiolite Complex. The accretionary prism beneath the ophiolite complex and the presence of boninites suggest that the Southeast Bohol Ophiolite Complex was emplaced in a forearc setting. The Southeast Bohol Ophiolite Complex formed during the Early Cretaceous in a suprasubduction zone environment related to a southeast‐facing arc (using present‐day geographical references). The accretion of this ophiolite complex was followed by a period of erosion and then later by extensive clastic and carbonate rock deposition (Carmen Formation, Sierra Bullones Limestone and Maribojoc Limestone). The Lumbog Volcaniclastic Member and Jagna Andesite document intermittent Tertiary volcanism in southeastern Bohol. 相似文献
17.
《International Geology Review》2012,54(8):1020-1038
ABSTRACTThe La Tinta mélange is a small but singular ultramafic mélange sheet that crops out in eastern Cuba. It is composed of dolerite-derived amphibolite blocks embedded in a serpentinite matrix. The amphibolite blocks have mid-ocean ridge basalt (MORB)-like composition showing little if any imprint of subduction zone component, similar to most forearc and MOR basalts worldwide. Relict Cr-spinel and olivine mineral chemistry of the serpentinized ultramafic matrix suggest a forearc position for these rocks. These characteristics, together with a hornblende 40Ar/39Ar age of 123.2 ± 2.2 Ma from one of the amphibolite blocks, suggest that the protoliths of the amphibolite blocks correspond to forearc basalt (FAB)-related rocks that formed during the earlier stage of subduction initiation of the Early Cretaceous Caribbean arc. We propose that the La Tinta amphibolites correspond to fragments of sills and dikes of hypoabyssal rocks formed in the earlier stages of a subduction initiation scenario in the Pacific realm (ca. 136 Ma). The forearc dolerite-derived amphibolites formed by partial melting of upwelling fertile asthenosphere at the beginning of subduction of the Proto-Caribbean (Atlantic) slab, with no interaction with slab-derived fluids/melts. This magmatic episode probably correlates with Early Cretaceous basic rocks described in Hispaniola (Gaspar Hernandez serpentinized peridotite-tectonite). The dikes and sills cooled and metamorphosed due to hydration at low pressure (ca. 3.8 kbar) and medium to high temperature (up to 720ºC) and reached ca. 500ºC at ca. 123 Ma. At this cooling stage, serpentinite formed after hydration of the ultramafic upper mantle. This process might have been favoured by faulting during extension of the forearc, indicating an early stage of dike and sill fragmentation and serpentinite mélanges formation; however, full development of the mélange likely took place during tectonic emplacement (obduction) onto the thrust belt of eastern Cuba during the latest Cretaceous. 相似文献
18.
西南“三江”格咱火山-岩浆弧中红山-属都蛇绿混杂岩带的厘定及其意义 总被引：13，自引：10，他引：3
义敦岛弧南段的格咱火山-岩浆弧的东西斑岩带在成矿期次、成矿作用等方面存在较大差异性,二者之间是否有大型构造单元的存在,与东部代表洋壳消减的甘孜-理塘主蛇绿混杂岩带关系如何等一直是悬而未决问题。研究发现,区内存在由断续出露镁铁-超镁铁堆积杂岩,以及尼汝组玄武岩、硅质板岩和复理石、灰岩等岩片组成的红山-属都蛇绿混杂岩带,属于甘孜-理塘洋壳早期俯冲残留次级蛇绿混杂岩带,与主蛇绿混杂岩带及格咱火山-岩浆弧构成了本区构造格架。其中,红山-属都蛇绿混杂岩带将格咱弧分为东西两个斑岩成矿带。本蛇绿混杂岩带的厘定,为进一步研究甘孜-理塘洋范围、俯冲时限、构造演化、甘孜-理塘洋是否存在两次俯冲,及格咱弧东西斑岩带成矿规律提供了基础资料,并对指导区域找矿具有一定意义。 相似文献
19.
湘东北文家市蛇绿混杂岩带的发现及意义 总被引：3，自引：2，他引：1
在湘东北文家市首次识别出蛇绿岩套残片 ,它由变沉积岩、变玄武岩、变辉绿岩、变辉长岩、变辉石岩类及变硅质岩组成。综合其地质学、岩石学、地球化学和同位素年代学的资料 ,提出文家市蛇绿岩可能形成于有限小洋盆的构造环境。文家市蛇绿混杂岩带、前陆盆地、磨拉石建造和“S”型花岗岩等构造岩石组合记录了碰撞造山的全过程 ,证实了江南雪峰古陆属元古宙造山带。这一发现为华南前寒武纪的大地构造格架和地壳演化提供了依据 ,同时该地区也将成为研究早期华南大陆地壳演化———武陵运动的关键地带。 相似文献