DOCSLIB.ORG

FROM OROGENIC to ANOROGENIC MAGMATISM : a PETROLOGICAL MODEL for the TRANSITION CALC-Alkallne - Alkallne COMPLEXES

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
FROM OROGENIC to ANOROGENIC MAGMATISM : a PETROLOGICAL MODEL for the TRANSITION CALC-Alkallne - Alkallne COMPLEXES Revista Brasileira de Geociências 17(4):366-371 , dezembro de 1987 FROM OROGENIC TO ANOROGENIC MAGMATISM : A PETROLOGICAL MODEL FOR THE TRANSITION CALC-ALKALlNE - ALKALlNE COMPLEXES BERNARD BONIN* ABSTRACT In many orogenic belts , the internal parts display a closely related in space and time association of calc-alkaline and alkaline igneous centres. The magmatic massifs are emplaced, during late-stage orogenic processes and post-orogenic tectonic episodes , in pull-apart molassic basins associated with large shear fault zones. When considering the nature of the igneous products in these structures, one can recognize members of orogenic suites (ca/c-a/ka/ine sensu lato) as well as of anorogenic suites (namely a/kaline and tholeiitic). Strike-slip movements and associated distensive fault zones control the locat ion and emplacement of magmatic produ cts but do not influence the nature of primary liquids. Therefore, the typical sequence: a. calc-alkaline batholith emplacement (uplift and unroofing), b. late calc-alkaline volcanic activity , c. early alkaline volcanic plateaus, and d. subsequent plutonic-volcanic alkaline ring-eomplexes has its petrogenetic explanation to be searched in deeper leveis than at the present erosion levei where it is observed. RESUMO Em muitos cinturões orogênícos as partes internas exibem uma associação estreita no espaço e no tempo , de centros cálcio-alcalinos e alcalinos. Os maciços magmáticos são colocados, durante os estágios tardios dos processos orog ênicos e episódios tectônicos p ós-orogênicos, em bacias molássicas de pull-apart vinculadas a grandes zonas de falhamento. Quand o se considera a naturez a dos produtos ígneos nessas estruturas, podem-se reconhecer membros das suítes orogênicas (cálcio­ -alcalina sensu lato ) bem como das suítes anorogênicas (denominadas alcalina e toleítica). Movimentos transco rrentes e zonas distensivas de falhamento associado controlam a locação e a colocação dos pro­ dutos magmático s, mas não influenciam a natureza dos líquidos primários. Assim sendo, para se explicar petrogeneticamente a seqüência típica: a. colocação do batólito cálcio-alcalino (ascensão e intrusão), b. atividade vulcânica-alcalina tardia, c. platô s vulcânicos alcalinos precoces, e d. subseqüen­ tes complexos alcalino anelares plutono-vulcânicos, é necessário pesquisa em níveis mais profundo s que os atuais níveis descobertos pela erosão o permitem. LATE- TO POST-OROGENIC MAGMATIC CENTRES Strait of the D'Entrecasteaux Islands, southeast Papua. DURING PHANEROZOIC TIMES There is abundant Lavas in this area are entirely comendite but basaltic and evidence that distinctive igneous rock association occur intermediate rock ty pes are foun d as lava blocks in in specific tectonic environrnents (for a review, see Pitcher pyroclastic deposits and as inclusions in comendite flows.The 1987). One such is the pera1kaline felsic rock association porphyritic comendites are Holocene in ageand show a close The tectonic settings of th is petrographically and geochem­ spatial association with Quaternary andesitic volcanoes. ically distinctive group of igneous rocks have been outlined Holocene pantellerite lavas and associated pyroclastics by MacDonald (1975): areas of uplift and rift formation, comprise the whole of the isolated volcano of Mayor Island more rarely of extensional tectonics, in continental as well in the Bay of Plenty on the northeastern side of North as in oceanic environments. The common factor of these Island, New Zealand. Intermediate rock types occur as lava various tectonic settings is that they are characterized by blocks and have been interpre ted as a part of the magmatic conditions of crustal -tension. In this context, the close association. spatial and tempo ral association of peralkaline felsic rocks The occurrence of obsidian in the Kaeo area ofNorthland with calc-alkalíne belts (now conceptually representing near the northern tip of North Island has been documente d converging plate boundaries and compressional tectonic since 1909 but the vent from which pantelleritic obsidian regimes) seems at a first glance to be anomalous, as stressed originated has not been identified. Obsidian blocks are by Srnith et ai. (1977). This "anomaly" is in fact a role for overlying Plio-Pleistocene basalts. the last stages of several orogenies having worked at the Srnith et ai. (1977) 'outline the general petrographical earth surface. and geochernical features of the peralkaline rhyolite associa­ tion: peralkaline rhyolites are either comendites (less Pe ralkaline rhyolites associated with andesitic peralkaline and Fe-rich, more alurninous) or pantellerites belts SOUTHWEST PACIFIC AREA Probably, the (more peralkaline and Fe-rich, less alurninous); the charac­ most recent occurrences of peralkaline volcanic rocks teristically low Ca, Ba, Sr and high contents of elements associated with andesitic volcanoes are located in three such as Th, U, and Zr support the hypothesis that peralkaline areas of the southwest Pacific (Smith et ai. 1977), namely rhyolites originate by fractional crystallization from a in the D'Entrecasteaux Islands, southeastern Papua-New transitional basalt parental magma. Guinea, and on Mayor Island and in the Kaeo area of Because it lies in the zone of interaction between the Northland, New Zealand. Indo-Australían and Pacific plates, the tectonic sett ing of Peralkaline silicic volcanic rocks, unique among the southeastern Papua has in general been interpreted in terms volcanic products of west Melanesia, occur in the Dawson of island are processes. In fact, Smith et aI. (1977) point * Laboratoire de P étrographie-Volcanologie. U.A. 728 du C.N.R.S., Université Paris-Sud, F-9l 4DS ORSAY CEDEX, France Revista Brasileira de Geociências, Volume 17, 1987 367 out that this is an oversimplified view of a complex plate Present ly, no satisfactory explanation in terms of plate boundary which has undergone dramatic polarity shifts boundary tectonics of the elose andesite-comendite associa­ within the past 50 Ma. They prefer the following interpreta­ tion has been proposed, because of the great complexity tion of the area: the late Cenozoic andesitic volcan ism, of rnicroplates implicated in the genesis of the Western although not elosely linked to recent subduction, is a con­ Mediterranean Basin (e.g. Dewey et aI. 1974). sequence of earlier subduction and a Quaternary spreading centre lies in the Woodlark Basin immediately to the east of the D'Entrecasteaux Islands . Thus, a late Tertiary Late- to post-Hercynian magmatic activity in Permo-Triassic compressional regime in southeast Papua is at present being time Rifts and pull-apart basins related to large shear replaced from the east by a tensional regime associated with fault zones are tectonically emplaced in the Hercynian sea-floor spreading in the Woodlark Basin. Srnith et aI. orogen (Arthaud & Matte 1977). They are not directly ( 977) suggest that peralkaline rhyolite products are early associated to ocean-type extensional regime but to stríke-slip manifestations of extensional tectonics and indicate a movements induced by the ending Variscan orogenic remarkably elose response of the petrogenetic process to process and essentially by the complete modification of the a change in tectonic regime. stress field (Ziegler 1983). During the whole Carboniferous The same geodynamic explanation is proposed from times, the compressional regime had an essentially north­ Mayor Island and Kaeo pantellerites. The peralkaline silicic -south direction and , at the Carboníferous-Permían bounda­ volcanism is interp reted as a consequence of back-arc ry, significant modifications of the compressional axis have spreading, especially where spreading centres impinge on resulted in a large dextral E-W shear movements (Fig . 1). andesit ic ares, SARDINIA The same picture can be outlined for the comendites of San Pietro Island , Sardinia, where this rock ty pe has been defined. The context is somewhat different as it implies thickened continental blocks. In this island, two magmatic suites have been emplaced at nearly the same time . The fírst ensemble comprises hype rsthene basalts, andesites and plagíoclase-bear íng rhyolites and it is markedly calc-alkal íne, The second ensemble is compositionally more restricted, with alkaline metaluminous rhyolites, comendites and pantellerites . Geochronological K/Ar data indicate that comendites, metalurninous alkaline rhyolites and calc-alkaline and esites are synchronous, yielding identical ages of about 15 Ma (Arana et aI. 1974). Mineralogical and geochernical studies evidence the role of the fractional crystallization in the differentiation of rhyolitic liquids (Laridhi 1981). Andesites and plagíoclase­ -bearing rhyolites have originated from the same mantle source yielding a Th/Ta rat io of 5-8. Alkaline rhyolites display distinctly different trace element contents and rati os, for example Th/Ta ratios of 3.5 for the metaluminous Figure 1 - Sketch map ofEurope during Stephanian-Autu­ rhyolit es, 4.0 for the comendites and 3. 2 for the nian times: Diagonal lines: inactive fold belt; cross-hatched pantellerites, indicating a distinctly different mantle source. area : active fold belt; squares: alkaline igneous centres; In her review, Laridhi (1981) shows that San Pietro cireles: calc-alkaline igneous centres. BBF- Bay ofBiscay comendites can be distinguished from comendites emplaced Fault zone; GSF - Gibraltar Strait Fault zone; TL ­ in an extensional regime by higher H20 contents (5-6 wt%), TornquistLine
Load more

Recommended publications
  • And Post-Collision Calc-Alkaline Magmatism in the Qinling Orogenic Belt, Central China, As Documented by Zircon Ages on Granitoid Rocks
    Journal of the Geological Societv. London, Vol. 153, 1996, pp. 409-417. Palaeozoic pre- and post-collision calc-alkaline magmatism in the Qinling orogenic belt, central China, as documented by zircon ages on granitoid rocks F. XUE'.*,',A. KRONER', T. REISCHMANN' & F. LERCH' 'Institut fiir Geowissenschaften, Universitat Mainz, 55099 Mainz, Germany 'Department of Geology, Northwest University, 710069 Xi'an, China .'Present address: Department of Geophysical Sciences, The University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637, USA Abstract: Basedon large-scale reconnaissance mapping, we identifiedtwo calc-alkaline plutonic assemblagesfrom the northern Qinling orogenic belt.central China. The older assemblage of intrusions. closely associated and deformed coevally with their host volcanic arc sequences, seems to represent the fractionation product of basaltic arc magma. It therefore predates the collision of the North China Block with the Central Qinling island-arc system that developed in a SW Pacific-type oceanic domain south of the North China Block. Single-zircon zo7Pb/2'"Pb evaporation dating yielded early to middle Ordovician ages for this assemblage. with a relatively small range from 487.2 f 1.1 to 470.2 f 1.3 Ma. Intrusions of the younger assemblage are largely undeformed and truncate structures shown in rocks of theolder assemblage. They are interpreted as post-collisional calc-alkaline granitoids.Single zircon dating provided an age of 401.8 f 0.8 Mafor the younger assemblage. consistentwith earlier work that defines an age range from c. 420 to 395Ma. Our datafavour a tectonicmodel involving formation and amalgamation of islandarc and microcontinent terranes between ca. 490 and 470 Ma ago to create the Central Qinling Zone which subsequently collided with theNorth China Block prior to c.
    [Show full text]
  • Neoproterozoic Glaciations in a Revised Global Palaeogeography from the Breakup of Rodinia to the Assembly of Gondwanaland
    Sedimentary Geology 294 (2013) 219–232 Contents lists available at SciVerse ScienceDirect Sedimentary Geology journal homepage: www.elsevier.com/locate/sedgeo Invited review Neoproterozoic glaciations in a revised global palaeogeography from the breakup of Rodinia to the assembly of Gondwanaland Zheng-Xiang Li a,b,⁎, David A.D. Evans b, Galen P. Halverson c,d a ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS) and The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University, GPO Box U1987, Perth, WA 6845, Australia b Department of Geology and Geophysics, Yale University, New Haven, CT 06520-8109, USA c Earth & Planetary Sciences/GEOTOP, McGill University, 3450 University St., Montreal, Quebec H3A0E8, Canada d Tectonics, Resources and Exploration (TRaX), School of Earth and Environmental Sciences, University of Adelaide, SA 5005, Australia article info abstract Article history: This review paper presents a set of revised global palaeogeographic maps for the 825–540 Ma interval using Received 6 January 2013 the latest palaeomagnetic data, along with lithological information for Neoproterozoic sedimentary basins. Received in revised form 24 May 2013 These maps form the basis for an examination of the relationships between known glacial deposits, Accepted 28 May 2013 palaeolatitude, positions of continental rifting, relative sea-level changes, and major global tectonic events Available online 5 June 2013 such as supercontinent assembly, breakup and superplume events. This analysis reveals several fundamental ’ Editor: J. Knight palaeogeographic features that will help inform and constrain models for Earth s climatic and geodynamic evolution during the Neoproterozoic. First, glacial deposits at or near sea level appear to extend from high Keywords: latitudes into the deep tropics for all three Neoproterozoic ice ages (Sturtian, Marinoan and Gaskiers), al- Neoproterozoic though the Gaskiers interval remains very poorly constrained in both palaeomagnetic data and global Rodinia lithostratigraphic correlations.
    [Show full text]
  • Extrusive and Intrusive Magmatism Greatly Influence the Tectonic Mode of Earth-Like Planets
    EPSC Abstracts Vol. 11, EPSC2017-945, 2017 European Planetary Science Congress 2017 EEuropeaPn PlanetarSy Science CCongress c Author(s) 2017 Extrusive and Intrusive Magmatism Greatly Influence the Tectonic Mode of Earth-Like Planets D. Lourenco, P. J. Tackley, A. Rozel and M. Ballmer Institute of Geophysics, Department of Earth Sciences, ETH Zurich, Switzerland ([email protected] / Fax: +41 44 633 1065) Abstract reported in [3], we use thermo-chemical global mantle convection numerical simulations to Plate tectonics on Earth-like planets is typically systematically investigate the effect of plutonism, in modelling using a strongly temperature-dependent conjugation with eruptive volcanism. Results visco-plastic rheology. Previous analyses have reproduce the three common tectonic/convective generally focussed on purely thermal convection. regimes usually obtained in simulations using a However, we have shown that the influence of visco-plastic rheology: stagnant-lid (a one-plate compositional heterogeneity in the form of planet), episodic (where the lithosphere is unstable continental [1] or oceanic [2] crust can greatly and frequently overturns into the mantle), and influence plate tectonics by making it easier (i.e. it mobile-lid (similar to plate tectonics). At high occurs at a lower yield stress or friction coefficient). intrusion efficiencies, we observe and characterise a Here we present detailed results on this topic, in new additional regime called “plutonic-squishy lid”. particular focussing on the influence of intrusive vs. This regime is characterised by a set of strong plates extrusive magmatism on the tectonic mode. separated by warm and weak regions generated by plutonism. Eclogitic drippings and lithospheric delaminations often occur around these weak regions.
    [Show full text]
  • The Western Amazonia Igneous Belt
    Journal of South American Earth Sciences 96 (2019) 102326 Contents lists available at ScienceDirect Journal of South American Earth Sciences journal homepage: www.elsevier.com/locate/jsames The Western Amazonia Igneous Belt T ∗ Gilmar José Rizzottoa, , Cléber Ladeira Alvesa, Francisco Sene Riosa, Márcia Aparecida de Sant’Ana Barrosb a Geological Survey of Brazil (CPRM), Rua 148, nº 485, 74170-110, Goiânia, Goiás, Brazil b Institute of Geosciences of the Federal University of Mato Grosso, Rua 44, No. 41, CEP 78.068-505, Cuiabá, Mato Grosso, Brazil ARTICLE INFO ABSTRACT Keywords: The Western Amazonia Igneous Belt (WAIB) occupies the northern part of South American continent, and a total Amazonian craton area close to 125,000 km2. The belt is composed dominantly by volcano-plutonic felsic rocks (Juruena super- Bimodal magmatism suite, Teles Pires suite and Colíder group) and has dominant alkali-calcic, metaluminous to peraluminous, fer- Underplating rous, geochemical characteristics, similar to A-type granites. The Silicic members are represented by granites and Teles pires suite rhyolitic-rhyodacitic volcanic rocks, mafic members by gabbroic rocks and diabase dykes. Intermediate rocks are rare. Local magma mingling and hybridization are present in several areas. The assemblage of silicic and basic rocks of WAIB was formed between c. 1825 and 1757 Ma. The presence of inherited zircons, from 1875 to 2050 Ma, as well as some Archean ages in the granitic and volcanic rocks from the WAIB, are suggestive of derivation by melting of pre-existing crustal basement (Ventuari-Tapajós Province). This hypothesis is also corroborated by bimodal magmatism and by several model-ages of granites, felsic volcanic rocks and mafic plutonic rocks, with TDM ranging from 2.0 to 2.3 Ga, and εNd value, varying from −3.90 to +2.52.
    [Show full text]
  • Volcanism in a Plate Tectonics Perspective
    Appendix I Volcanism in a Plate Tectonics Perspective 1 APPENDIX I VOLCANISM IN A PLATE TECTONICS PERSPECTIVE Contributed by Tom Sisson Volcanoes and Earth’s Interior Structure (See Surrounded by Volcanoes and Magma Mash for relevant illustrations and activities.) To understand how volcanoes form, it is necessary to know something about the inner structure and dynamics of the Earth. The speed at which earthquake waves travel indicates that Earth contains a dense core composed chiefly of iron. The inner part of the core is solid metal, but the outer part is melted and can flow. Circulation (movement) of the liquid outer core probably creates Earth’s magnetic field that causes compass needles to point north and helps some animals migrate. The outer core is surrounded by hot, dense rock known as the mantle. Although the mantle is nearly everywhere completely solid, the rock is hot enough that it is soft and pliable. It flows very slowly, at speeds of inches-to-feet each year, in much the same way as solid ice flows in a glacier. Earth’s interior is hot both because of heat left over from its formation 4.56 billion years ago by meteorites crashing together (accreting due to gravity), and because of traces of natural radioactivity in rocks. As radioactive elements break down into other elements, they release heat, which warms the inside of the Earth. The outermost part of the solid Earth is the crust, which is colder and about ten percent less dense than the mantle, both because it has a different chemical composition and because of lower pressures that favor low-density minerals.
    [Show full text]
  • Environmental Effects of Large Igneous Province Magmatism: a Siberian Perspective Benjamin A
    20 Environmental effects of large igneous province magmatism: a Siberian perspective benjamin a. black, jean-franc¸ois lamarque, christine shields, linda t. elkins-tanton and jeffrey t. kiehl 20.1 Introduction Even relatively small volcanic eruptions can have significant impacts on global climate. The eruption of El Chichón in 1982 involved only 0.38 km3 of magma (Varekamp et al., 1984); the eruption of Mount Pinatubo in 1993 involved 3–5km3 of magma (Westrich and Gerlach, 1992). Both these eruptions produced statistically significant climate signals lasting months to years. Over Earth’s his- tory, magmatism has occurred on vastly larger scales than those of the Pinatubo and El Chichón eruptions. Super-eruptions often expel thousands of cubic kilo- metres of material; large igneous provinces (LIPs) can encompass millions of cubic kilometres of magma. The environmental impact of such extraordinarily large volcanic events is controversial. In this work, we explore the unique aspects of LIP eruptions (with particular attention to the Siberian Traps), and the significance of these traits for climate and atmospheric chemistry during eruptive episodes. As defined by Bryan and Ernst (2008), LIPs host voluminous (> 100,000 km3) intraplate magmatism where the majority of the magmas are emplaced during short igneous pulses. The close temporal correlation between some LIP eruptions and mass extinction events has been taken as evidence supporting a causal relationship (Courtillot, 1994; Rampino and Stothers, 1988; Wignall, 2001); as geochronological data become increasingly precise, they have continued to indicate that this temporal association may rise above the level of coincidence (Blackburn et al., 2013). Several obstacles obscure the mechanisms that might link LIP magmatism with the degree of global environmental change sufficient to trigger mass extinction.
    [Show full text]
  • Geochemistry and Tectonic Significance of Late Paleoproterozoic A-Type Granites Along the Southern Margin of the North China
    www.nature.com/scientificreports OPEN Geochemistry and tectonic signifcance of late Paleoproterozoic A-type granites along the southern margin of the North China Craton Yan Wang1, Yi-Zeng Yang1*, Wolfgang Siebel2, He Zhang1, Yuan-Shuo Zhang1 & Fukun Chen1 The Longwangzhuang pluton is a typical example of Paleoproterozoic A-type granite intrusions at the southern margin of the North China Craton. This pluton is composed of arfvedsonite granite and minor aegirine–augite granites. Samples from both granite types display similar zircon U-Pb ages with 207U-206Pb ages of 1612 ± 19 Ma [mean square weighted deviation (MSWD) = 0.66] and 1609 ± 24 Ma (MSWD = 0.5), respectively. The granites exhibit similar high silica (SiO2 = 71.1–73.4 wt.%), high alkaline (Na2O + K2O = 8.10–9.26 wt.%, K2O/Na2O > 1), and low Al2O3 (11.8–12.8 wt. %) contents and metaluminous to weakly peraluminous bulk chemistry. The chemical variations of the Longwangzhuang pluton suggest the efects of mineral fractionation. In addition, all samples show typical characteristics of A-type granites, such as high 10000Ga/Al ratios (4.10–7.28), high FeOtot/(FeOtot + MgO) ratios (0.88– 0.99), and high Zr (484–1082 ppm), Ce (201–560 ppm), and Y (78–156 ppm) contents. The εNd(t) values 206 204 207 204 208 204 and the ( Pb/ Pb)t, ( Pb/ Pb)t, and ( Pb/ Pb)t ratios of the arfvedsonite granite samples vary from −4.6 to –5.3, 15.021 to 17.349, 15.241 to 15.472, and 33.206 to 36.905, respectively, and those for the aegirine–augite granite sample amount at −0.2, 14.421, 15.175, and 33.706.
    [Show full text]
  • Provenance and Implication of Carboniferous–Permian Detrital
    minerals Article Provenance and Implication of Carboniferous–Permian Detrital Zircons from the Upper Paleozoic, Southern Ordos Basin, China: Evidence from U-Pb Geochronology and Hf Isotopes Ziwen Jiang 1, Jinglan Luo 1,*, Xinshe Liu 2,3, Xinyou Hu 2,3, Shangwei Ma 4, Yundong Hou 2,3, Liyong Fan 2,3 and Yuhua Hu 1 1 State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, China; [email protected] (Z.J.); [email protected] (Y.H.) 2 State Engineering Laboratory of Exploration and Development for Low Permeability Oil and Gas Fields, Xi’an 710018, China; [email protected] (X.L.); [email protected] (X.H.); [email protected] (Y.H.); [email protected] (L.F.) 3 Research Institute of Petroleum Exploration and Development, PetroChina Changqing Oilfield Company, Xi’an 710018, China 4 Shaanxi Mineral Resources and Geological Survey, Xi’an 710068, China; [email protected] * Correspondence: [email protected] Received: 9 February 2020; Accepted: 13 March 2020; Published: 15 March 2020 Abstract: Carboniferous–Permian detrital zircons are recognized in the Upper Paleozoic of the whole Ordos Basin. Previous studies revealed that these Carboniferous–Permian zircons occurred in the Northern Ordos Basin mainly originated from the Yinshan Block. What has not been well documented until now is where this period’s zircons in the Southern Ordos Basin came from, and very little discussion about their provenance. To identify the provenance of the detrital zircons dating from ~350 to 260 Ma, five sandstone samples from the Shan 1 Member of Shanxi Formation and eight sandstone samples from the He 8 Member of Shihezi Formation were analyzed for detrital zircon U-Pb age dating and in situ Lu-Hf isotopic compositions.
    [Show full text]
  • Fifth International Dyke Conference
    FIFTH INTERNATIONAL DYKE CONFERENCE Abstracts and Programme NAL DYKE TIO C A O N N R F E E T R N I E N H C T F E I F 5 IDC F D I N L A N 31 July - 3 August 2005, Pohtimolampi Wilderness Hotel - Polar Circle - Rovaniemi - Finland FIFTH INTERNATIONAL DYKE CONFERENCE 31.7 – 3.8.2005 – ROVANIEMI, FINLAND FIFTH INTERNATIONAL DYKE CONFERENCE "Dyke swarms - time markers of crustal evolution" Pohtimolampi Wilderness Hotel - Polar Circle - Rovaniemi - Finland 31 June – 3 August 2005 ABSTRACTS AND PROGRAMME edited by Jouni Vuollo Geological Survey of Finland P.O. Box 77, FIN-96101 Rovaniemi Satu Mertanen Geological Survey of Finland P.O. Box 96, FIN-02151 Espoo ISBN 951-690-926-4 i FIFTH INTERNATIONAL DYKE CONFERENCE 31.7 – 3.8.2005 – ROVANIEMI, FINLAND Reference (an example): Alaabed S., 2005. Intrusion types of the mantle sequence of the northern Semail ophiolite (UAE Section). In: Vuollo, J. and Mertanen, S. (eds.), 5th International Dyke Conference, 31 July – 3 August 2005, Rovaniemi, Finland, Abstracts and Programme, p. 1. ii FIFTH INTERNATIONAL DYKE CONFERENCE 31.7 – 3.8.2005 – ROVANIEMI, FINLAND Welcome from the Organising Committee Welcome to Rovaniemi! We are very pleased to host you here as a participant of the Fifth International Dyke Conference (IDC- 5). The conference will bring together specialists in volcanology, tectonics, structural geology, petrology, geochemistry, geochronology, and geophysics to present progress made in the last years in various subjects related to dykes and other sheeted intrusions. An important part of the meeting are the pre- and post-conference excursions to the southern and eastern Finland and to the Kola Peninsula, Russia.
    [Show full text]
  • Magma Genesis, Plate Tectonics, and Chemical Differentiation of the Earth
    REVIEWS OF GEOPHYSICS, VOL. 26, NO. 3, PAGES 370-404, AUGUST 1988 Magma Genesis, Plate Tectonics, and Chemical Differentiation of the Earth PETER J. WYLLIE Division of Geolo•7icaland Planetary Sciences,California Institute of Technolo•Ty,Pasadena Magma genesis,migration, and eruption have played prominent roles in the chemical differentiation of the Earth. Plate tectonics has provided the framework of tectonic environments for different suites of igneousrocks and the dynamic mechanismsfor moving massesof rock into melting regions.Petrology is rooted in geophysics.Petrological and geophysicalprocesses are calibrated by the phase equilibria of the materials. The geochemistry of basalts and mantle xenoliths demonstrates that the mantle is hetero- geneous.The geochemical reservoirs are related to mantle convection, with interpretation of a mantle layered or stratified or peppered with blobs. Seismic tomography is beginning to reveal the density distribution of the mantle in three dimensions,and together with fluid mechanical models and interpreta- tion of the geoid, closer limits are being placed on mantle convection. Petrological cross sectionscon- structed for various tectonic environments by transferring phase boundaries for source rocks onto assumedthermal structuresprovide physical frameworks for consideration of magmatic and metasoma- tic events,with examplesbeing given for basalts,andesites, and granites at ocean-continentconvergent plate boundaries, basalts and nephelinitesfrom a thermal plume beneath Hawaii, kimberlites in cratons,
    [Show full text]
  • Volcanic and Magmatic Rocks - J
    EARTH SYSTEM: HISTORY AND NATURAL VARIABILITY - Vol. I - Volcanic and Magmatic Rocks - J. Ulrych and V. Cajz VOLCANIC AND MAGMATIC ROCKS J. Ulrych and V. Cajz Institute of Geology, Academy of Sciences of the Czech Republic, Prague, Czech Republic Keywords: Magma, lava, petrology, magmatism, plutonism, volcanism, classification, igneous rocks, plutonic, dyke and volcanic rocks, pyroclastic rocks, structure and texture of rocks, volcanology, landforms of volcanic products, intrusive and extrusive (effusive) products, utilization of rocks, zeolites Contents 1. State of the Art 2. Origin of Igneous Rocks 3. Forms of Plutonic and Subvolcanic Bodies 3.1 Abyssal Bodies 3.2 Subvolcanic Bodies 4. Landforms of Surface Volcanic Products 5. Classification and Characteristics of Principal Igneous Rocks 5.1 Plutonic Rocks 5.1.1. Granites and Granitoids (Alkali-Feldspar Granites, Granodiorites and Quartz Diorites) and Syenites 5.1.2 Gabbros and Diorites 5.1.3 Anorthosites 5.1.4 Ultramafic Plutonic Rocks (Peridotites, Pyroxenites, Hornblendites) 5.1.5 Carbonatites 5.1.6 Charnockites 5.2 Dyke Rocks 5.2.1 Porphyry 5.2.2 Lamprophyric Rocks (Lamprophyres, Lamproites, Kimberlites) 5.3 Volcanic Rocks 5.3.1 Basalts and Basaltoids (including Trachybasalt, Tephrite, Basanite, Olivine Foidite) 5.3.2 TrachytesUNESCO and Phonolites – EOLSS 5.3.3 Andesites and Dacites 5.3.4 Rhyolites 6. Importance and Utilization of Igneous Rocks Glossary SAMPLE CHAPTERS Bibliography Biographical Sketches Summary The Earth‘s internal regime is associated with heat derived from the radioactivity of U, Th, and K, and from the early thermal history of the planet. This internal heat causes plate motions, earthquakes, orogenic movements, and volcanic activity on the surface of the Earth.
    [Show full text]
  • The Rhyacian El Cortijo Suture Zone: Aeromagnetic Signature and Insights for the Geodynamic Evolution of the Southwestern Rio De La Plata Craton, Argentina
    Geoscience Frontiers 5 (2014) 43e52 Contents lists available at SciVerse ScienceDirect China University of Geosciences (Beijing) Geoscience Frontiers journal homepage: www.elsevier.com/locate/gsf Research paper The Rhyacian El Cortijo suture zone: Aeromagnetic signature and insights for the geodynamic evolution of the southwestern Rio de la Plata craton, Argentina Carlos J. Chernicoff a,b,*, Eduardo O. Zappettini b, Javier Peroni b a Council for Scientific and Technical Research (CONICET), Argentina b Argentine Geological-Mining Survey (SEGEMAR), Argentina article info abstract Article history: The amalgamation of the southern Río de la Plata craton involves two possibly coeval Rhyacian sutures Received 21 September 2012 associated with the Transamazonian orogeny, rather than a single one as previously envisaged, i.e. the El Received in revised form Cortijo suture zone and the Salado suture. We circumscribe the Tandilia terrane to the region between 20 March 2013 these two sutures. Accepted 15 April 2013 The El Cortijo suture zone runs along a roughly WNW oriented magnetic low aligned along the Available online 7 May 2013 southern boundary of the Tandilia terrane, i.e. boundary between the Tandilia and Balcarce terranes. This extensive magnetic low, ca. 300 km long, and ca. 90 km wide, would be caused by demagnetization Keywords: El Cortijo suture zone associated with shearing. At a more local scale, the trend of the El Cortijo suture zone often turns e Rhyacian toward the E W. At this scale, WNW trending tholeiitic dykes of Statherian age are seen to cut the Río de la Plata craton Rhyacian El Cortijo suture zone. Spatially associated with the El Cortijo suture zone, there are small Aeromagnetics magnetic highs interpreted to be related to unexposed basic bodies of ophiolitic nature related to those forming part of the El Cortijo Formation.
    [Show full text]