Journal of The Virtual Explorer最新文献

{"title":"Variscan metamorphism in Sardinia, Italy: review and discussion","authors":"M. Franceschelli, M. Puxeddu, G. Cruciani","doi":"10.3809/JVIRTEX.2005.00121","DOIUrl":"https://doi.org/10.3809/JVIRTEX.2005.00121","url":null,"abstract":"The Sardinian segment of the Variscan chain is divided into four tectonometamorphic zones from NE to SW: 1) Inner zone, with mediumto high-grade metamorphic rocks and migmatites; 2) Internal Nappe zone, with lowto medium-grade rocks; 3) External Nappe zone, with low-grade metamorphic rocks; 4) External zone, with very lowto low-grade rocks. Metabasite lenses, with eclogite and granulite relics, occur in the migmatites. Pre-Variscan ages are attributed to the E-W trending folds below the Sardic unconformity (SW Sardinia). Five Variscan deformation phases have been distinguished, the principal ones being: D1, compressional, with SW-vergent folds and S1 schistosity; D2, extensional, with S2 schistosity transposing S1. Later, a composite network of post-D3, synD4 shear zones was active from an older HT/LP shear event to a younger MT-LT/LP one. The late D5 phase produced kilometric flexures with an axis parallel to the orogenic trend. For Inner zone sequences, a complete prograde sequence has been recognised, from the chlorite zone to the sillimanite + K-feldspar one. The Nappe zone shows decreasing metamorphic grade from bottom to top of the Nappe pile, as well as in each single unit. The Variscan P-T-t path is the clockwise loop typical of continental collision. For the Barrovian stage, thermobarometers yielded a Ppeak of ≈1.2 GPa (end of D1) and Tpeak of ≈750°C (early D2). For HP/HT metamorphic relics, calculations indicated: eclogite stage, T ≈ 550°-700°C, P ≈ 1.3-1.7 GPa; granulite stage, T ≈ 650°-900°C, P ≈ 0.8-1.2 GPa; amphibolite stage: T ≈ 550°-650°C, P ≈ 0.3-0.7 GPa. Pre-Variscan igneous rocks consist of Lower to Middle Paleozoic metabasites with MORB or WPB affinity and Middle Ordovician calc-alkaline intrusive and effusive rocks. The Corsica-Sardinia microplate belongs to the southern passive margin of the Hun Superterrane of the Swiss authors. The beginning of Variscan continental collision is marked by a probable eclogite-producing HP event. Ages of 355-335 Ma and 335-320 Ma for the first two Variscan metamorphic phases and 310-280 Ma and 290-280Ma for late-post orogenic Variscan magmatism in Sardinia match those of the same events in the northern Hun Superterrane active leading margin. The Variscan Corsica-Sardinia batholith is made up of late-orogenic calc-alkaline intrusive rocks and post orogenic leucogranites. The greater volumes (surface area≈ 12000 Km2) and long gestation times of the Corsica-Sardinia batholith as compared to those of the northern Hun Superterrane batholiths is attributed to the collision between the southern Hun Superterrane margin, including Corsica-Sardinia, and the huge Gondwana Supercontinent. Journal of the Virtual Explorer, 2005 Volume 19","PeriodicalId":201383,"journal":{"name":"Journal of The Virtual Explorer","volume":"442 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115854600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D Structure Of The Northern Marche Region, And Implications For The Active Tectonics Of The Outer Northern Apennines (Italy)","authors":"F. Borraccini, M. Donatis, S. Mazzoli, D. Savelli","doi":"10.3809/JVIRTEX.2005.00113","DOIUrl":"https://doi.org/10.3809/JVIRTEX.2005.00113","url":null,"abstract":"","PeriodicalId":201383,"journal":{"name":"Journal of The Virtual Explorer","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125187820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new eclogitic unit in the Cottian Alps: The Roccenie calcschist /ophiolite complex, Val Varaita - Val Po (Piemonte, Italy)","authors":"A. Borghi, M. Gattiglio, B. Lombardo, A. Michard, F. Mondino","doi":"10.3809/JVIRTEX.2004.00096","DOIUrl":"https://doi.org/10.3809/JVIRTEX.2004.00096","url":null,"abstract":"","PeriodicalId":201383,"journal":{"name":"Journal of The Virtual Explorer","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125239545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quicktime movies of 3D spiral inclusion trail development","authors":"A. Stallard, H. Ikei, T. Masuda","doi":"10.3809/JVIRTEX.2002.00063","DOIUrl":"https://doi.org/10.3809/JVIRTEX.2002.00063","url":null,"abstract":"","PeriodicalId":201383,"journal":{"name":"Journal of The Virtual Explorer","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131285944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A review of the Brasiliano magmatism in southern Espírito Santo, Brazil, with emphasis on post-collisional magmatism","authors":"C. P. Campos, J. Mendes, I. P. Ludka, S. Medeiros, J. Moura, C. M. Wallfass","doi":"10.3809/JVIRTEX.2004.00106","DOIUrl":"https://doi.org/10.3809/JVIRTEX.2004.00106","url":null,"abstract":"","PeriodicalId":201383,"journal":{"name":"Journal of The Virtual Explorer","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127662454","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geology of the Beltana Willemite Deposit","authors":"A. Kallio","doi":"10.3809/JVIRTEX.2005.00138","DOIUrl":"https://doi.org/10.3809/JVIRTEX.2005.00138","url":null,"abstract":"","PeriodicalId":201383,"journal":{"name":"Journal of The Virtual Explorer","volume":"870 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127795221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Some Frequently Asked Questions about the Mount Isa Deposit, and Enigmatic Textures of the Ores","authors":"W. Perkins","doi":"10.3809/JVIRTEX.2008.00187","DOIUrl":"https://doi.org/10.3809/JVIRTEX.2008.00187","url":null,"abstract":"","PeriodicalId":201383,"journal":{"name":"Journal of The Virtual Explorer","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132713085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analogue modelling of segregation and ascent of magma","authors":"P. Bons, J. Dougherty-Page, M. Elburg","doi":"10.3809/JVIRTEX.2001.00029","DOIUrl":"https://doi.org/10.3809/JVIRTEX.2001.00029","url":null,"abstract":"","PeriodicalId":201383,"journal":{"name":"Journal of The Virtual Explorer","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133179805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hot Rocks: The Flinders Ranges Crystalline Basement","authors":"J. Hiess","doi":"10.3809/JVIRTEX.2005.00136","DOIUrl":"https://doi.org/10.3809/JVIRTEX.2005.00136","url":null,"abstract":"","PeriodicalId":201383,"journal":{"name":"Journal of The Virtual Explorer","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114229718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical characteristics of the granitoids of Mikir Hills massif of Shillong plateau, Northeast India: implication for Pan-African magmatic activity","authors":"M. Hussain, T. Ahmad","doi":"10.3809/JVIRTEX.2009.00250","DOIUrl":"https://doi.org/10.3809/JVIRTEX.2009.00250","url":null,"abstract":"Mikir Hills massif (MHM) of the Shillong plateau, in northeastern India extends over an area of about 7000 km 2 . MHM vis-a-vis Shillong plateau record granite magmatism from 881 to 479 Ma related to Pan-African magmatic event. The analysed MHM granitoids have SiO 2 ranging from 64.5 wt.% to 75.8 wt.%; Al 2 O 3 content ranges from 13 to 14 wt.%; CaO content ranges from 1.3 to 3.3 wt.% and the total alkalies range from 7.2 wt.% to 8 wt.%. The granitoids show steeply fractionated chondrite normalized rare earth element (REE) patterns with (La/Yb) N varying between 18 and 28, strong negative Eu anomaly, and flat heavy REE patterns. They have enriched large ion lithophile element (LILE) abundances relative to high field strength elements (HFSE) with negative Nb, Sr, P and Ti anomalies in the Primitive Mantle normalized multi-elemental patterns. In the tectonic discrimination diagrams, the granitoids plot within volcanic arc granite filed. These geochemical signatures point towards a subduction related magmatism in the Shillong plateau. The Neoproterozoic granitoids of Shillong plateau with arc geochemical signature and with the plateau at the leading margin of Neoproterozoic Indian plate, place constraints on the evolution of these rocks and their significance in dispersal of Rodinia and subsequent assembly of the Gondwana supercontinent.","PeriodicalId":201383,"journal":{"name":"Journal of The Virtual Explorer","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117274442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}