Zusammenfassung
Der archaische Kraton Südindiens ist durch eine komplexe, noch nicht vollständig aufgeklärte geologische Entwicklungsgeschichte gekennzeichnet. Sie umfaßt mehrere Zyklen von Sedimentation und Vulkanismus, Deformation und Metamorphose in der Zeitspanne von etwa 3400 bis 2500 Ma. Die großregionale metamorphe Zonierung wird im wesentlichen als das Ergebnis eines Metamorphose-Ereignisses vor ca. 2600 Ma angesehen, das den gesamten archaischen Komplex aus granitoiden Gneisen, Migmatiten und „Greenstone“-Serien erfaßte.
Das südliche Gebiet ist durch Bedingungen der Granulitfazies (700–750° C/8–10 kb) charakterisiert. Hier entstand eine ausgedehnte Charnockit-Khondalit-Zone durch post-tektonische Umwandlung der Migmatit-Gneisserien infolge Zufuhr einer CO2-reichen fluiden Phase. Nach Norden zu nimmt der Metamorphosegrad bis zur niedrigtemperierten Amphibolitfazies (600° C/6–8 kb) und in den Dharwar-„Greenstone Belts“ sogar bis zur Grünschieferfazies (400° C) ab.
Eine jüngere Metamorphose von Amphibolit-bis Grünschieferfazies ist auf proterozoische Scherzonen beschränkt. Im südlichen Gebiet führte sie zu einer örtlich unterschiedlich intensiven retrograden Überprägung der Charnockit-Khondalit-Serie.
Die P-, T-Bedingungen der Regionalmetamorphose wurden anhand von Mineralstabilitätsdaten und mit Methoden der Geothermometrie und Geobarometrie für das Gebiet zwischen Shimoga-Chitradurga (Norden) und Coimbatore-Karur (Süden) abgeleitet.
Abstract
The Archaean craton of southern India is characterized by a highly complicated and not yet fully understood geological history comprizing several cycles of sedimentation and volcanism, deformation and metamorphism in the span between about 3400 and 2500 m. y. The large scale regional variation in metamorphic grade observed today is essentially related to a metamorphic event at about 2600 m. y. ago which affected an older migmatite, gneiss-greenstone terrain (2900–3400 m. y.).
The southern area is characterized by granulite facies (700–750° C/8–10 kb). An extensive charnockite-khondalite belt has been generated by atectonic transformation of the migmatite-gneiss terrain through the influx of a CO2-rich fluid. Towards the north of the terrain the metamorphic grade decreases to amphibolite facies (600° C/6–8 kb) and to greenschist facies (400° C) which is restricted to the Dharwar greenstone belts. Metamorphism related to younger shear zones in the southern part of the craton led to retrogression of the charnockite-khondalite series under conditions of amphibolite to greenschist facies.
The P-T conditions of metamorphism have been evaluated applying mineral stability data and methods of geothermometry and geobarometry in an area between Shimoga-Chitradurga (North) and Coimbatore-Karur (South).
Résumé
Le craton archéen de l'Inde méridionale est caractérisé par une évolution géologique complexe et mal connue. Elle comprend plusieurs cycles de sédimentation et de volcanisme, de déformation et métamorphisme d'une durée d'environ 3400 jusqu'à 2500 Ma.
La variation du degré de métamorphisme observée aujourd'hui est considérée comme le résultat d'un épisode de métamorphisme datant d'environ 2600 Ma, qui a affecté l'ensemble du domaine archéen composé de granitoïdes et de ceintures de roches vertes.
La région méridionale de craton est caractérisée par le faciès granulite (700–750 °C/ 8–10 kb). Une zone étendue de charnockites et khondalites est le produit d'une transformation postdéformative résultant de l'apport d'une phase fluide riche en CO2. Vers le nord le degré de métamorphisme décroit jusqu'au faciès amphibolites (600 °C/6–8 kb) et même jusqu'au faciès schistes verts (400 °C) dans les ceintures dharwariennes de roches vertes.
Un épisode tardif de métamorphisme de faciès amphibolites et schistes verts est limité aux zones à décollement intense d'âge protérozoïque. Dans la région méridionale il s'est produit un rétromorphisme des roches granulitiques dans la zone des charnockites et khondalites.
Les conditions de pression et température ont été déduites de l'application de données sur la stabilité des minéraux et de méthodes de géothermométrie et de géobarométrie pour la région entre Shimoga-Chitradurga (nord) et Coimbatore-Karur (sud).
Краткое содержание
Архейский кратон южн ой Индии характеризу ется сложной, еще не полнос тью установленной геоло гическое историей ра звития. Она охватывает многочис ленные циклы осадконакопле ния и вулканизма, дефо рмации и метаморфизма, происходившие приме рно от 3400 до 2500 миллионов л ет тому назад.
Разделение на крупны е зоны метаморфизма в общем расматривают, как рез ультат некого события метам орфизма, имевшего мес то примерно 2600 миллионов лет тому назад, которо е охватило весь архей ский комплекс, состоящий из гранитоидных гней сов, мигматитов и „зеленокаменных“ се рий.
Южная область характ еризуется условиями гранулитовой фации (700–750 °С, 8–10 кб). Здесь образов алась обширная облас ть чарнокитов/хондалит ов в резултате послетек тонических процессо в в мигматитово-гнейсов ой серии в присутствии флюидно й фазы, богатой СО2. Сте пень метаморфизма возрас тает к северу до фации низк отемпературных амфи болитов (600 °С, 6–8 кб) й даже до фации зеленосланц ев в зеленокамнном по ясе Dharwar (400 °С). Поздний метаморфизм амфибол итовой до зеленослан цевой фации ограничивается прот ерозойской зоной скалывания. В юж ных провинциях она пр иводит к ретроградному преобразованию чарн окит/хондалитовой се рии, имеющей локальное значение и обладающе й различной интенсив ностью. Об условиях давления и температуры при рег иональном метаморфизме судят по данным стаби льности минералов, и н а основании геотермометрически м и геобарометрически м данным в области меж ду Shimoga-Chitradurga (север) и Coimbatore-Karur (юг).
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Literature
Beckinsale, R. D., Drury, S. A., andHolt, R. W.: 3360 M yr old gneisses from the South Indian craton. Nature,283, 469–470, 1980.
Chadwick, Ramakrishnan, M., Viswanatha, M. N., andSrinivasa Murthy, V.: Structural studies in the Archaean Sargur and Dharwar supracrustal rocks of the Karnataka craton. J. Geol. Soc. India19, 531–549, 1979.
Crawford, A. R.: Reconnaissance Rb-Sr dating of the Precambrian rocks of southern Peninsular India. J. Geol. Soc. India10, 117–166, 1969.
Drury, S. A., andHolt, R. W.: The tectonic framework of the South Indian craton: a reconaissance involving LANDSAT imagery. Tectonophysics 65, T1-T15, 1980.
Ellis, D. J.: Osumilite-sapphirine-quartz granulite from Enderby Land, Antarctica: P-T conditions of metamorphism, implications for garnet-cordierite equilibria and the evolution of the deep crust. Contrib. Mineral. Petrol.74, 201–210, 1980.
Ellis, D. J., andGreen, D. H.: An experimental study of the effect of Ca upon garnetclinopyroxene Fe-Mg exchange equilibria. Contrib. Mineral. Petrol.71, 13–22, 1979.
Ferry, J. M., andSpear, F. S.: Experimental calibration of the partitioning of Fe and Mg between biotite and garnet. Contrib. Mineral. Petrol.66, 113–117, 1978.
Geochemistry Group: Archaean Geochemistry-contributions and programmes of NGRI. Geophys. Res. Bull.15, 1–54, 1977.
Ghent, E. D.: Applications of activity-composition relations to displacement of a solid-solid equilibrium grossular-anorthite + kyanite + quartz. In: Greenwood, H. J. (ed.), Short course in applications of thermodynamics to petrology and ore deposits. Mineral. Ass. Canada, 99–108, 1977.
Grady, J. C.: Deep main faults in India. J. Geol. Soc. India12, 56–62, 1971.
Janardhan, A. S., Ramachandra, H. M., andKumar, G. R. R.: Structural history of Sargur supracrustals and associated gneisses, southwest of Mysore, Karnataka. J. Geol. Soc. India20, 61–72, 1979 a.
Janardhan, A. S., Newton, R. C., andSmith, J. V.: Ancient crustal metamorphism at low PH20: charnockite formation at Kabbaldurga, South India. Nature278, 511–514, 1979.
Jayaram, S., Venkatasubramanian, V. S., andRadhakrishna, B. P.: Pb-Sr ages of cordierite gneisses of southern Karnataka. J. Geol. Soc. India17, 557–561, 1976.
Katz, M. B.: Tectonic evolution of the Archaean granulite facies belt of Sri Lanka - South India. J. Geol. Soc. India19, 185–205, 1978.
Pichamuthu, C. S.: Transformation of Peninsular gneiss to charnockites in Mysore State, India. J. Geol. Soc. India2, 46–49, 1961.
—: Precambrian of India, in Rankama, K. (Edit.) “The Precambrian” Vol. 3, 58–77, Wiley & Sons, New York, 1967.
—: Precambrian geochronology of Peninsular India. J. Geol. Soc. India12, 262–273, 1971.
Radhakrishna, B. P.: Peninsular gneissic complex of the Dharwar craton - a suggested model for its evolution. J. Geol. Soc. India15, 439–454, 1974.
Radhakrishna, B. P., andVasudev, V. N.: The early Precambrian of the southern Indian Shield. J. Geol. Soc. India18, 525–541, 1977.
Ramakrishnan, M., Viswanatha, M. N., andSwami Nath, J.: Basement-cover relationship of Peninsular gneiss with high-grade schists and greenstone belts of southern Karnataka. J. Geol. Soc. India17, 97–111, 1976.
Ramiengar, A. S., Ramakrishnan, M., andViswanatha, M. N.: Charnockite-Gneisscomplex relationship in southern Karnataka. J. Geol. Soc. India19, 411–419, 1978.
Spooner, C. M., andFairbairn, H. W.: Strontium 87/Strontium 86 initial ratios in pyroxene granulite terrains. Jour. Geophys. Res.75, 6706–6713, 1970.
Srinivasan, R., andSreenivas, B. L.: Some new geological features from Landsat imagery of Karnataka. J. Geol. Soc. India18, 589–597, 1977.
Swami Nath, J., Ramakrishnan, M., andViswanatha, M. N.: Dharwar stratigraphic model and Karnataka craton evolution. Rec. Geol. Surv. India107, 149–175, 1976.
Venkatasubramanian, V. S., andNarayanaswamy, R.: Ages of some gneissic pebbles in Kaldurga conglomerates. J. Geol. Soc. India15, 318–319, 1974.
Weaver, B. L., Tarney, J., Windley, B. F., Sugavanam, E. B., andVenkata Rao, V.: Madras granulites: geochemistry and P-T conditions of crystallization. In: Windley, B. F., and Naqvi, S. M. (Edit.), Development in Precambrian Geology Vol. 1, Archaean Geochemistry, 177–204, Elsevier, Amsterdam, 1978.
Wells, P. R.: Pyroxene thermometry in simple and complex systems. Contrib. Mineral. Petrol.62, 129–139, 1977.
—: Chemical and thermal evolution of Archaean Sialic crust, Southern Greenland. J. Petrol.20, 187–226, 1979.
Wood, B. J.: Solubility of alumina in orthopyroxene coexisting with garnet. Contrib. Mineral. Petrol.46, 1–15, 1974.
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The present study is part of a joint project of Benaras Hindu University at Varanasi and University of Kiel. Financial Support by the Deustche Forschungsgemeinschaft is gratefully acknowledged.
We especially thank M. N. Viswanatha, Geological Survey of India, for his cooperation during the field work.
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Raith, M., Raase, P., Ackermand, D. et al. The Archean Craton of Southern India: Metamorphic evolution and P-T conditions. Geol Rundsch 71, 280–290 (1982). https://doi.org/10.1007/BF01825042
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DOI: https://doi.org/10.1007/BF01825042