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1.
The Cooma Metamorphic Complex, a low-P, high-T (LPHT) regional aureole beneath the Murrumbidgee Batholith 总被引：1，自引：0，他引：1
The Cooma Complex of the Lachlan Fold Belt, south‐eastern Australia, is characterised by a large (c. 10 km wide) low‐P, high‐T metamorphic aureole surrounding a small (3 × 6 km) granite pluton. The aureole extends northward to envelop the eastern lobe of the Murrumbidgee Batholith and progressively narrows to a kilometre wide hornfelsic aureole some 50 km north of Cooma. At its northern extremity, the batholith has intruded its own volcanic cover. These regional relations suggest that the Murrumbidgee Batholith is gently tilted to the north, with the Cooma Complex representing the aureole beneath the batholith. Two main deformation events, D3 and D5, affected the aureole. The inner, high‐grade migmatitic domain contains upright F5 folds defined by a composite, transposed S3/S0 fabric and S3/S0 concordant leucosomes. The folded stromatic migmatites define the western limb of a F5 synform, with its axis located in the batholith. Lenses and sheets of the Murrumbidgee Batholith intruded along S3 but also preserve S3 as a strong, solid‐state foliation. S3 and the granite sheets but are also folded by F5, outlining a fanning positive flower structure. These relations indicate that most of the batholith was emplaced before and during D3, but intrusion persisted until early syn‐D5. Formation of the Cooma Granodiorite occurred post‐D3 to early syn‐D5, after formation of the wide metamorphic aureole during early syn‐D3 to early syn‐D5. The Murrumbidgee Batholith was emplaced between pre‐D3 to early syn‐D5, synchronous with the formation of the Cooma Complex. The structural and metamorphic relations indicate that the Murrumbidgee Batholith was the ultimate heat source responsible for the Cooma Metamorphic Complex. D3 structures and metamorphic isograds are subparallel to the batholith margin for over 50 km. This concordance probably extends vertically, suggesting that the isograds also fan outward from the batholith margin. This implies an inverted metamorphic sequence focused on the Murrumbidgee Batholith, although the base has been almost completely removed by erosion in the Cooma Complex. The field evidence at Cooma, combined with previous thermal modelling results, suggest that extensive LPHT metamorphic terranes may represent regional metamorphic aureoles developed beneath high‐level granitic batholiths. 相似文献
2.
Hezbullah Moiny Shah Wali Faryad Renata Čopjaková Radim Jedlicka 《Journal of Metamorphic Geology》2020,38(7):693-717
Basement rocks from the Western Hindu Kush preserve evidence of multiple metamorphic and magmatic events that occurred along the boundary between the Archean–Proterozoic Afghan Central and Afghan–Tajik Blocks. To verify the different metamorphic stages or events, mineral textures and phase equilibria in metamorphic basement rocks and their age relations to magmatic episodes have been investigated. Quartzofeldspathic gneiss and migmatite with lenses of amphibolite (with assumed Proterozoic age for their metamorphism) are intruded by the Triassic Hindu Kush granitoid batholith and small Cretaceous and Oligocene granite intrusions. The age of thermal overprint (210–170 Ma) by the Triassic batholith is confirmed by new monazite data. Both Triassic and Cretaceous granitoids and surrounding basement rocks underwent subsequent metamorphism up to epidote–amphibolite facies. The degree of this metamorphism increases southward at the contact to the Kabul Block, which under-plates the Western Hindu Kush from the south. An early Miocene age was obtained by Pb–Th analyses in thorite and huttonite, which are close or slightly younger than the Oligocene granite in this area. The Cretaceous meta-granodiorite near the border with the Kabul Block contains xenoliths of granulite facies rocks that could come from the Neoarchean granulite facies basement of the Kabul Block. The multi-stage metamorphic and magmatic evolution classifies the Hindu Kush mountain belt as a long-lived suture zone that was active since the early Palaeozoic. The results of this study support the interpretation about possible relations of the Afghan Central Blocks to the southern margin of Eurasia during the evolution of Para- and Neotethys. 相似文献
3.
4.
D. A. Lykhin V. I. Kovalenko V. V. Yarmolyuk A. B. Kotov V. P. Kovach 《Geology of Ore Deposits》2010,52(4):289-301
An isotopic study of igneous and metamorphic rocks has been carried out at the Yermakovsky bertrandite-phenakite-fluorite
deposit. It has been established that the model age of the schists pertaining to the Zun-Morino Formation is 1360–1260 Ma.
In Nd and Sr isotopic composition, these schists deviate from the isotopic composition of the continental crust and are close
in this respect to the enriched mantle reservoir (EM-II). The model age of carbonate rocks of the Zun-Morino Formation is
1330–1020 Ma. The Middle Riphean model age of the Zun-Morino Formation is interpreted as the age of its protolith. According
to the Sr and Nd isotopic data, all preore igneous rocks (granitic dikes, gabbroic rocks, and gneissose granite of the Tsagan
Complex) were formed with the participation of continental crustal material. Synore basic dikes, alkali leucogranite stock,
and syenite intrusion are considered to be mixtures of mantle components (DM+HIMU) and various continental crustal components
(Tsagan gneissose granite, crystalline schists, the mean composition of granitoids of the Angara-Vitim batholith as an estimate
of average composition of the regional continental crust). Synore igneous rocks are genetically cognate and related to the
magmatic activity in the Western Transbaikal Rift Zone presumably formed in the Triassic under effect of a mantle plume. 相似文献
5.
D. B. Clarke C. B. McKenzie G. K. Muecke S. W. Richardson 《Contributions to Mineralogy and Petrology》1976,56(3):279-287
Accessory andalusite has been found in some late-stage granitic differentiates of the South Mountain batholith. The andalusite is petrographically distinct from the andalusite of the thermal aureole, and it occurs in regions of the batholith which show little evidence of contamination by the country rocks. Analyses of biotites from andalusite-bearing and andalusite-free phases suggest that those coexisting with andalusite actually grew in equilibrium with the andalusite. It is concluded that magmatic andalusite must be confined mainly to water-saturated, peraluminous, epizonal granites, and some possible P-T paths for the crystallization of magmatic andalusite are considered. 相似文献
6.
Quartz‐rich veins in metapelitic schists of the Sanandaj‐Sirjan belt, Hamadan region, Iran, commonly contain two Al2SiO5 polymorphs, and, more rarely, three coexisting Al2SiO5 polymorphs. In most andalusite and sillimanite schists, the types of polymorphs in veins correlate with Al2SiO5 polymorph(s) in the host rocks, although vein polymorphs are texturally and compositionally distinct from those in adjacent host rocks; e.g. vein andalusite is enriched in Fe2O3 relative to host rock andalusite. Low‐grade rocks contain andalusite + quartz veins, medium‐grade rocks contain andalusite + sillimanite + quartz ± plagioclase veins, and high‐grade rocks contain sillimanite + quartz + plagioclase veins/leucosomes. Although most andalusite and sillimanite‐bearing veins occur in host rocks that also contain Al2SiO5, kyanite‐quartz veins crosscut rocks that lack Al2SiO5 (e.g. staurolite schist, granite). A quartz vein containing andalusite + kyanite + sillimanite + staurolite + muscovite occurs in andalusite–sillimanite host rocks. Textural relationships in this vein indicate the crystallization sequence andalusite to kyanite to sillimanite. This crystallization sequence conflicts with the observation that kyanite‐quartz veins post‐date andalusite–sillimanite veins and at least one intrusive phase of a granite that produced a low‐pressure–high‐temperature contact aureole; these relationships imply a sequence of andalusite to sillimanite to kyanite. Varying crystallization sequences for rocks in a largely coherent metamorphic belt can be explained by P–T paths of different rocks passing near (slightly above, slightly below) the Al2SiO5 triple point, and by overprinting of multiple metamorphic events in a terrane that evolved from a continental arc to a collisional orogen. 相似文献
7.
广西海洋山花岗岩体侵位构造特征 总被引：1，自引：0，他引：1
花岗岩是大陆地壳的重要组成部分,是地球动力学演化的示踪剂。花岗岩体侵位构造的研究对于揭示花岗岩体的变形历史和侵位机制具有重要的科学价值。本文研究了海洋山花岗岩体的内部构造、与岩浆侵位应力有的围岩构造及热接触变质带特征,探讨了岩体和围岩的应变状态。研究发现,从岩浆侵位到冷凝固结,海洋山花岗岩体经历了液态流动、塑性变形和“半固态”冷凝阶段的演化。岩体各单元的应变类型分别是单轴压扁、平面应变、单轴压缩, 相似文献
8.
PETROLOGY AND AGE OF THE KINNAR KAILAS GRANITE:EVIDENCES FOR AN ORDOVICIAN POST-OROGENIC EXTENSION IN THE HIGHER HIMALAYAN CRYSTALLINE, SUTLEJ, INDIA 相似文献
9.
Contact metamorphism of greenschist facies Neoproterozoic turbidites by the Cretaceous Bugaboo Batholith in southeastern British Columbia has resulted in a well‐developed contact aureole. The aureole is about 1 km wide and can be divided into three main zones: (i) spotted phyllite zone, extending from the first appearance of spots of cordierite or andalusite to the last occurrence of primary chlorite; (ii) cordierite + andalusite + biotite zone, comprising hornfelses or schists with abundant porphyroblasts of cordierite and andalusite and, at higher grades, fibrolitic sillimanite; and (iii) K‐feldspar zone, characterized by hornfelses and schists that, in the inner part of this zone, are variably migmatitic. Four parts of the aureole were examined, three of which are characterized by schists, and one of which (Cobalt Lake area) is characterized by hornfelses and has exceptional exposure and comparatively unaltered rocks. Petrographic, modal, mineral‐compositional and whole rock‐compositional data were collected from the Cobalt Lake transect, allowing the prograde reaction sequence to be inferred. Notable features of the aureole at Cobalt Lake include: initial development of andalusite and plagioclase at the expense of paragonite‐rich white mica; a narrow interval across which cordierite, andalusite and biotite increase markedly at the expense of chlorite; gradual development of andalusite and biotite at the expense of cordierite and muscovite upgrade of chlorite consumption; and near‐simultaneous development of andalusite + K‐feldspar and sillimanite, the latter indicating a pressure of contact metamorphism of ~3 kbar. In other parts of the aureole, the development of sillimanite downgrade of the initial development of K‐feldspar suggests slightly higher pressures of contact metamorphism. Lack of correspondence between the observed sequence of reactions in the aureole and those predicted thermodynamically suggests that modifications to some of the thermodynamic data or activity–composition models may be required. Textural features in the aureole suggest the influence of kinetic factors on metamorphic recrystallization, including: (i) deformation‐catalysed reaction in the schists compared to the hornfelses, as indicated by different mineral‐growth sequences inferred from microstructures, and (ii) heating rate‐controlled recrystallization, as indicated by the decrease in grain size of hornfelses with increasing metamorphic grade. 相似文献
10.
Abstract. Many granitic plutons of Early Cretaceous age are intruded on various scales in the Kitakami Mountains. The stock‐type Ganidake pluton accompanies enormous Fe‐Cu mineralization of the Kamaishi deposits, whereas the Kurihashi pluton accompanies less mineralization. To elucidate the cause of these differences, the metamorphic conditions and redox state of the contact metamorphic aureole around the Kurihashi pluton have been examined by the petrochemical study and gas analysis of the metamorphic rocks. A typical mineral assemblage in the pelitic rocks in the lowest‐grade part is biotite‐muscovite‐chlorite‐quartz‐plagio‐clase‐graphite, which occur more than 2 km away from the contact point with the Kurihashi pluton. Graphite disappears at the 1550 m point, and cordierite and garnet appear in the middle and highest‐grade parts, respectively. A typical mineral assemblage in the tuffaceous rocks in the lower‐grade part is chlorite‐actinolite‐biotite‐quartz‐plagioclase. Actinolite changes into hornblende near to the pluton. The CO2/CH4 ratios obtained in measurements by gas chromatography exceeds 100 in the pelitic rocks at the contact point with the pluton. The ratios decrease and become less than 0.1 with distance from the pluton. Equilibrium temperatures calculated from a garnet‐biotite pair in the pelitic rock and a hornblende‐plagioclase pair in the tuffaceous rock are 640d? and 681 d?C at the contact point, respectively. The log?o2 values among these metamorphic aureoles estimated from the CO2/CH4 ratios are slightly lower than the FMQ‐buffer. Redox states of the contact metamorphic aureole are kept in an intermediate condition between oxidized magma of the Kurihashi pluton and graphite‐bearing pelitic country rocks. Judging from these metamorphic conditions around the Kurihashi pluton and from the re‐evaluation of the previous knowledge about contact metasomatism around the Ganidake pluton, the Kurihashi metamorphism has occurred at higher temperatures and dry conditions than the Ganidake metasomatism. These differences in the metamorphic conditions and presence or absence of a large limestone mass around the pluton might be the principal reasons why the Kurihashi pluton accompanies less mineralization and the Ganidake pluton accompanies gigantic Kamaishi skarn mineralization. 相似文献
11.
V. J. Morand 《Australian Journal of Earth Sciences》2013,60(3):339-353
The Wyangala Batholith, in the Lachlan Fold Belt of New South Wales, is pre‐tectonic with respect to the deformation that caused the foliation in the granite, and was emplaced during a major thermal event, perhaps associated with dextral shearing, during the Late Silurian to Early Devonian Bowning Orogeny. This followed the first episode of folding in the enclosing Ordovician country rocks. Intrusion was facilitated by upward displacement of fault blocks, with local stoping. Weak magmatic flow fabrics are present. After crystallization of the granite, a swarm of mafic dykes intruded both the granite and country rock, possibly being derived from the same tectonic regime responsible for emplacement of the Wyangala Batholith. A contact aureole surrounding the granite contains cordierite‐biotite and cordierite‐andalusite assemblages. Slaty cleavage produced in the first deformation was largely obliterated by recrystallization in the contact aureole. Postdating granite emplacement and basic dyke intrusion, a second regional deformation was accompanied by regional metamorphism ranging from lower greenschist to albite‐epidote‐amphibolite facies, and produced tectonic foliations, termed S and C, in the granite, and a foliation, S2, in the country rocks. Contact metamorphic rocks underwent retrogressive regional metamorphism at this time. S formed under east‐west shortening and vertical extension, concurrently with S2. C surfaces probably formed concurrently with S and indicate reverse fault motion on west‐dipping ductile shear surfaces. The second deformation may be related to Devonian or Early Carboniferous movement on the Copperhannia Thrust east of the Wyangala Batholith. 相似文献
12.
C. M. Gray A. I. S. Kemp J. A. C. Anderson D. J. Bushell D. J. Ferguson J. Fitzherbert 《Australian Journal of Earth Sciences》2013,60(2):187-200
The Cambro‐Ordovician Glenelg tectonic zone of western Victoria is a distinctive metamorphic‐igneous segment of the Delamerian Orogenic Belt comprising two northwest‐striking regional metamorphic segments of andalusite‐sillimanite type prograding towards an axial granitic batholith. The second of five deformations (D2) was most significant, producing isoclinal folds, transposition and a pervasive regional foliation (S2). Southwest of the central batholith, biotite to migmatite zones contain mainly quartzo‐feldspathic rock (turbiditic metagreywacke, quartzo‐feldspathic schist and migmatite), plus less common metaquartzite and calc‐silicate rocks and minor metapelite. Metagabbro, metadolerite and amphibolite typically have the chemistry of mid‐ocean ridge basalts. Serpentinite pods and sheets were tectonically introduced to low‐grade areas. Northeast of the central batholith, quartzo‐feldspathic rock occupies the sillimanite and migmatite zones exclusively, with a regional concentration of pegmatites adjacent to the zone boundary. Gross interleaving of quartzo‐feldspathic schist, migmatite, pegmatite and muscovite‐bearing granitic rock is characteristic. Peak metamorphic conditions of 550 MPa at 640°C leading to migmatite formation were established by D2 time and accompanied by tonalite‐granodiorite and pegmatite emplacement. Subsequently, the thermal high contracted to the northeast culminating in the more extensive syn‐, post‐D4 to pre‐D5 granitic magmatism. 相似文献
13.
俯冲隧道是俯冲板片与上覆板块之间的剪切带,也是高压—超高压变质岩折返和深部流/熔体活动的通道。大别山超高压变质岩分布广泛,变形程度差异很大,是研究大陆俯冲隧道中岩石变质- 变形过程的理想地区。本文系统总结了前人对中大别双河地区超高压变质岩的岩石学和年代学研究成果,在双河地区开展了地质填图、应变分析和三维构造重建。通过将超高压变质岩的变形特征与P- T- t轨迹结合,识别出超高压变质岩折返过程中的三期韧性变形。在双河北部发现了一个上盘向NW剪切的千米尺度的榴辉岩相鞘褶皱,枢纽向SE倾伏,倾伏角约20°,与榴辉岩、片岩和长英质片麻岩的拉伸线理平行,表明超高压变质岩初始折返阶段的流体活动使榴辉岩的强度显著降低,榴辉岩与围岩一起发生韧性变形。该期变形被角闪岩相退变质阶段上盘向NW的剪切叠加,此时应变集中于片麻岩、片岩、大理岩等非能干层,强度较高的榴辉岩成为构造透镜体。而绿片岩相变质阶段上盘向SE方向的剪切与早白垩世北大别花岗片麻岩穹隆的形成有关。对双河南部弱变形花岗片麻岩的锆石U- Pb定年揭示了757±14 Ma的原岩年龄和 240~216 Ma的变质年龄,与双河北部含柯石英强变形花岗片麻岩类似,暗示其也经历了三叠纪超高压变质作用及随后的角闪岩相退变质作用。通过计算长英质片麻岩的有效黏度,发现无水碱长花岗片麻岩的有效黏度高于黑云斜长片麻岩,折返阶段的流体活动使超高压变质岩的强度显著降低,当局部的流体活动不足以弱化碱长花岗岩体时,应变集中于黑云斜长片麻岩。因此,大陆俯冲隧道中的应变分布受矿物组成、流体活动和岩体规模的共同影响。 相似文献
14.
Bryan E. Chenhall Brian G. Jones Paul F. Carr 《Australian Journal of Earth Sciences》2013,60(3):389-401
Contact metamorphism has been recognized along a 4 km wide belt adjacent to the shallow‐dipping eastern margin of the Arthursleigh Tonalite, an Early Devonian pluton of the Marulan Batholith, eastern New South Wales. In Ordovician psammitic and pelitic rocks three zones of progressive contact metamorphism range from muscovite + biotite + chlorite assemblages in the outer zone to K‐feldspar + cordierite assemblages adjacent to the pluton and in metasedimentary xenoliths. Retrograde phenomena include extensive replacement of metamorphic minerals by ‘sericite’ and chlorite. Calcareous metasediments adjacent to the tonalite typically contain assemblages of quartz + calcic plagioclase + ferrosalite + sphene, or wollastonite + calcite + diopside with minor grossularite and vesuvianite. Thermal effects in volcanic rocks along the western margin of the pluton are confined to recrystallization of the groundmass. The regional geology indicates confining pressures of approximately 1 kbar at the time of emplacement of the tonalite. Contact metamorphic temperatures were estimated from two‐feldspar geothermometry to attain a maximum of approximately 590°C for rocks in the innermost zone of the aureole and 700°C for the xenoliths. Fluid compositions attending progressive contact metamorphism were water‐rich (Xco2<0.2) and, during cooling, these fluids probably account for the extensive retrograde hydration observed in the aureole. 相似文献
15.
Silica depleted melting of pelites. Petrogenetic grid and application to the Susqueda Aureole, Spain 总被引：2，自引：0，他引：2
Metapelitic rocks in the low pressure contact metamorphic aureole around the Susqueda igneous complex, Spain show a number of features that make them an ideal testing ground for the modelling of silica‐undersaturated melting. Rocks in the aureole experienced localized depletion in silica by the segregation of quartz veins during a pre‐anatectic, regional cordierite‐andalusite grade metamorphic event. These rocks were then intruded by gabbroic to dioritic rocks of the Susqueda igneous complex that formed a migmatitic contact metamorphic aureole in the country rocks. This migmatisation event caused quartz‐saturated hornfels and restite formation in rocks that had experienced no quartz vein segregation in the previous regional metamorphic event, but silica‐undersaturated melting in those rocks that were previously depleted in silica. Silica‐undersaturated melting is investigated using a new petrogenetic P–T projection and equilibrium pseudosections calculated in the KFMASH and NCKFMASH systems, respectively. The grid considers quartz absent equilibria and a range of phases that form typically in silica‐undersaturated bulk compositions, for example corundum. It is shown that the quartz‐rich precursors in the Susqueda contact aureole produced about 10% melt during contact metamorphism. However, most of this melt was extracted leaving behind rocks with restitic bulk compositions and minor leucosome segregation. It is suggested that the melt mixed with the host igneous rocks causing an apparent magmatic zoning from diorite in the centre of the complex to tonalite at the margins. In contrast, the quartz‐poor precursors (from which the quartz veins segregated) melted in the silica‐undersaturated field producing a range of assemblages including peritectic corundum and spinel. Melting of the silica‐undersaturated rocks produced only negligible melt and no subsequent melt loss. 相似文献
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17.
Three groups of Sn-W veins occur in the contact aureole of composite granitic plutons South of Bragança (Trás-os-Montes, Portugal). Thin layers of calcic quartzites with or without scheelite are interbedded in the Ordovician and Silurian metamorphic country-rocks. Could they represent synsedimentary preconcentrations and a likely source for the W-deposits? The geologic features and the trace-elements distribution (W, Sn, Be, B, Li, F, Rb) in the metasedimentary and granitic rocks support the following conclusions: 1) the scheelite-bearing calcic quartzites are tactites, that occur only in the contact aureole of the granites; 2) the dynamo-metamorphic country-rocks are weakly enriched in W and impoverished in Sn compared to the "clarke" values; 3) the trace-elements concentration is higher in the contact aureole (X 2) than outwards; 4) the quartzites are scheelite-bearing only in the vicinity of the wolframite veins. Thus, scheelite appears related to mineralizing hydrothermal processes. Through their chemical composition and their mechanical properties, the calcic quartzites appear as traps for a tungsten mainly foreign to the metamorphic rocks close to the granites. Thus, the source of W lies deeper in lower crust levels or in the upper-mantle. 相似文献
18.
也谈大兴安岭南段前进场岩体成因类型和形成环境 总被引：3，自引：0，他引：3
前进场岩体在岩石地球化学方面以过铝、富集ＬＲＥＥ、具中等负Ｅｕ异常为特征，∑ＲＥＥ介于１０７．８１－１４３．２４μｇ／ｇ之间，结合其野外地质特征和区域构造分析，本文认为该岩体为板块碰撞期间于晚石炭世由沉积物质部分熔融而形成的Ｓ型花岗岩。 相似文献
19.
S. Wyhlidal W. F. Th?ny P. Tropper R. Kaindl C. Hauzenberger V. Mair 《Mineralogy and Petrology》2012,106(3-4):173-191
The Brixen Granodiorite is part of the Permian calc-alkaline plutonic association (Brixen Granodiorite, Ifinger Granite, Kreuzberg Granite, Cima d’Asta Granitoid) that intruded the Variscan Southalpine metamorphic basement. The Brixen Granodiorite is located to the south of the Periatriatic Lineament in the eastern part of the Southalpine basement complex and comprises a series of tonalitic, granitic and granodioritc intrusions, which were emplaced during the Permian (280?Ma) into the country rocks of the Brixen Quarzphyllites. The depth of these Southalpine granodioritic intrusions was less than 10?km (P?≤?0.3?GPa) and solidus temperatures were 670–720?°C (Visona, Mem Sci Geol 47:111–124, 1995; Acquafredda et al., Miner Petrogr Acta XL:45–53, 1997; Wyhlidal et al., Austr J Earth Sci 102:181–192, 2009). Only a small, about 200?m wide, contact aureole formed at the southern rim of the Brixen Granodiorite near the village Franzensfeste/Fortezza (South-Tyrol, Italy). Within the contact aureole four different zones can be distinguished based upon mineralogical, mineral chemical and textural features. Approximately 200?m from the granite contact zone I occurs. The rocks from this zone are macroscopically still quartzphyllites and are characterized by two texturally and chemically different generations of micas (muscovite, biotite) and the appearance of cordierite. Zone II is characterized by quartzphyllites containing pseudomorphs of cordierite + biotite after garnet. The inner contact aureole (zone III) starts approximately 50?m from the granite contact and shows already typical hornfels textures. This zone is characterized by the first occurrence of andalusite. In the innermost area (zone IV), ca 10?m from the granite contact, spinel and corundum occur. Geothermometry (two-feldspar-, Ti-in-biotite) yielded an increase in temperature from 540?°C in the outermost aureole (zone I) to <740?°C in the innermost aureole (zone IV). Pseudosection modelling of hornfelses from zones III and IV also resulted in similar P-T conditions of <0.28?GPa and <620?°C. This contact aureole represents one of the few well-developed remaining areas of Permian contact metamorphism in the Southalpine domain, which are otherwise mostly obliterated by late-stage hydrothermal alteration in the course of the Alpine tectonic overprint. 相似文献