Post-Grenvillean transpression in the Chilka Lake area, Eastern Ghats Belt—implications for the geological evolution of peninsular India

Dobmeier, Christoph; Simmat, Ralf

doi:10.1016/s0301-9268(01)00212-1

Cited by 98 publications

(40 citation statements)

References 34 publications

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“…Similar variation is observed in the age of emplacement for the anorthosites as well as alkaline plutons, compiled in Figure 2 [anorthosites of Balangir and Chilka lake area, circa 1.4 Ga, Rb-Sr data, Sarkar et al, 1981;0.93 -0.79 Ga, zircon ages, Krause et al, 2001;Dobmeier and Simmat, 2002, and alkaline rocks 856 Ma -1.5 Ga; Clark and Subbarao, 1971;Subbarao et al, 1989;Sarkar and Paul, 1998;Aftalion et al, 2000;Upadhyay et al, 2006aUpadhyay et al, , 2006b]. However, all these studies are based on limited sample sets from these plutons.…”

Section: Geochronologysupporting

confidence: 73%

Timing and dynamics of the juxtaposition of the Eastern Ghats Mobile Belt against the Bhandara Craton, India: A structural and zircon U‐Pb SHRIMP study of the fold‐thrust belt and associated nepheline syenite plutons

2007

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Sensitive High Resolution Ion MicroProbe (SHRIMP) U‐Pb dating of zircon from basement granite gneisses and nepheline syenites of the Sinapalli Nappe, occurring along the northwestern margin of the Eastern Ghats Mobile Belt, indicate high grade regional metamorphism and associated folding accompanying juxtaposition of the nappe with the Bhandara Craton, to have taken place between 617 ± 85 Ma (lower intercept age of a reworked basement unit) and 517 Ma (age of the youngest syenite). This shows, for the first time, that the final juxtaposition of the northwestern parts of the Eastern Ghats Mobile Belt against the Bhandara Craton came about in the late Neoproterozoic and not, as previously thought, during the Mesoproterozoic. The northwestern part of the Eastern Ghats Mobile Belt comprises a fold‐ thrust belt consisting of a stack of northwesterly verging nappes that have been thrust over the Bhandara Craton. The Sinapalli Nappe is the lowermost nappe and rests over a tectonic contact on the Archean granites and gneisses of the craton. The basal décollement is exposed as a two‐km‐wide ductile‐brittle thrust, hosting nepheline syenite plutons that show fabrics consistent with a synkinematic emplacement during thrusting. The Sinapalli Nappe is comprised of a sequence of alternating mafic granulites and quartzofeldspathic gneisses with slivers of basement granites, which are folded in three phases of folding (F1, F2 and F3) and were subjected to granulite facies metamorphism during F1 folding. Thrusting is synkinematic to F2 folding and is responsible for the juxtaposition of the northwestern part of the Eastern Ghats Terrane over the Bhandara Craton during the assembly of parts of eastern Gondwana.

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Section: Geochronologysupporting

confidence: 73%

Timing and dynamics of the juxtaposition of the Eastern Ghats Mobile Belt against the Bhandara Craton, India: A structural and zircon U‐Pb SHRIMP study of the fold‐thrust belt and associated nepheline syenite plutons

2007

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“…Massive and disseminated Fe-Ti concentrations occur in gabbros and anorthosites, and the layered Selvåg gabbroic intrusion (Priesemann and Krause, 1985) represents a minor potential for Fe-Ti ore. Massif-type anorthosites also outcrop in southwest Madagascar (Ashwal et al, 1998) and India, which were both part of East Gondwana. The Eastern Ghats Belt of India hosts four massif-type anorthosite complexes (Bhattacharya et al, 1998;Krause et al, 2001;Dobmeier and Simmat, 2002;Dobmeier, 2006;Chatterjee et al, 2008). Other massifs are also described in south India (Janardhan and Wiebe, 1985), but no ore bodies have been discovered.…”

Section: Spatial and Temporal Distributionmentioning

confidence: 99%

Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks

Charlier

Namur

Bolle

et al. 2015

Earth-Science Reviews

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a b s t r a c t a r t i c l e i n f oMagmatic rocks containing economic concentrations of iron, titanium, vanadium and phosphorous are commonly associated with massif-type anorthosites and related rocks. This rock association is part of the anorthositemangerite-charnockite-(rapakivi-)granite suites that are restricted to the Proterozoic. Understanding the geochemistry and emplacement mechanisms of ilmenite, magnetite and apatite ore deposits is crucial for exploration, efficient mining operations and ore processing. This review discusses the controlling factors on the grade of an ore, its mineralogy, and its major and trace element distribution. We present petrogenetic models of currently mined deposits (Lac Tio, Tellnes, Damiao) and discuss the characteristics of minor ore bodies from anorthosite provinces worldwide (Grenville, North China Craton, East European Craton, Rogaland, Laramie). Models of formation of anorthosite and related rocks are presented, as well as the nature of the possible parental magmas of the suite. A mineralogical classification of Fe-Ti ores is proposed: (1) Gabbro-noritic ilmenite ore ± apatite ± magnetite; (2) Ti-magnetite-dominated ore; (3) Nelsonite (Fe-Ti oxides + apatite); and (4) Rutile-ilmenite ore. The stability of ilmenite and magnetite is then critically reviewed and the influence of various factors, particularly oxygen fugacity and crystallization pressure, is examined. We discuss liquidus compositions of Fe-Ti oxides and the behavior of important trace elements such as Cr and V, both of which are sensitive to fO 2 variations. Postcumulus evolution of both oxides can occur due to re-equilibration with trapped liquid, re-equilibration with ferromagnesian silicates, exsolution, oxidation, reaction between ilmenite and magnetite, and metamorphic overprinting. These various processes are described and their effects on the oxide geochemistry are emphasized. Several potential ore-forming processes have been invoked and can explain the formation of huge concentration of ilmenite, ±magnetite, ±apatite. Fractional crystallization can be combined with crystal sorting and plagioclase buoyancy to produce relative enrichment of dense ore minerals. Silicate liquid immiscibility can segregate conjugate Si-rich and Fe-rich melts, the latter being enriched in Fe-Ti-P. Magma mixing can produce hybrid magmas located in a single-phase field of the phase diagram and precipitate a pure ilmenite cumulate. Alternative processes are also described, such as ejection of Fe-Ti-enriched residual melts by filter-pressing and compaction, solidstate remobilization of ilmenite in veins, and hydrothermal transport of Fe and Ti from the host anorthosite followed by concentration in veins and lenticular ore bodies. The magnetic properties of Fe-Ti ore deposits present contrasting signatures, depending on whether the natural remanent magnetization is dominated by hemo-ilmenite or multi-domain magnetite. Micro-and macro-scale deformation features of ore rocks are intimately correlated with magma emplacement, and...

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“…One of the reasons for the generation of discordant U -Pb isotopic ages that is sometimes reported from SHRIMP monazite is related to the mixing of different age domains, due to the relatively large width of the ion probe beam (Crowley & Ghent 1999). Due to the much smaller beam width of the microprobe (*3 mm), chemical ages in monazite can potentially record detrital relics, the initial timing of crystallisation (from an igneous protolith) and all subsequent tectonothermal events (Copeland et al 1988;Dobmeier & Simmat 2002;Cocherie et al 2005;Pyle et al 2005). Importantly, a number of experimental studies, and studies of natural rock systems, have shown that monazite lacks significant diffusion processes within a closed system at temperatures 47508C, and possibly even as high as *9008C (Copeland et al 1988;Parrish 1990;Montel et al 1996;Braun et al 1998;Cocherie et al 1998;Crowley & Ghent 1999;Rubatto et al 2001;Cherniak et al 2004).…”

Section: Monazite Systematics and Age Determinationmentioning

confidence: 99%

Timing of Proterozoic metamorphism in the southern Curnamona Province: implications for tectonic models and continental reconstructions ∗

Rutherford

Hand

Barovich

2007

Australian Journal of Earth Sciences

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Chemical U -Th -Pb monazite ages from metasedimentary and meta-igneous units of the Willyama Supergroup have confirmed initial SHRIMP U -Pb metamorphic zircon ages constraining the onset of the earliest tectonometamorphic event (the Olarian Orogeny) at ca 1610 Ma in the southern Curnamona Province. An additional episode of high-grade metamorphism and heterogeneously distributed retrograde metamorphism and monazite recrystallisation occurred between ca 1570 and 1550 Ma. On the basis of monazite chemical U -Th -Pb ages from across the southern Curnamona Province, tectonometamorphic models based on ca 1690 Ma low-P, high-T metamorphism in the southern Curnamona Province are not supported. Furthermore, tectonic reconstructions that rely on the correlation of ca 1690 Ma deformation and metamorphism in the Broken Hill region with a similar aged event in the Mojave tarrane of southwestern Laurentia (AUSWUS) are not supported.

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Post-Grenvillean transpression in the Chilka Lake area, Eastern Ghats Belt—implications for the geological evolution of peninsular India

Cited by 98 publications

References 34 publications

Timing and dynamics of the juxtaposition of the Eastern Ghats Mobile Belt against the Bhandara Craton, India: A structural and zircon U‐Pb SHRIMP study of the fold‐thrust belt and associated nepheline syenite plutons

Timing and dynamics of the juxtaposition of the Eastern Ghats Mobile Belt against the Bhandara Craton, India: A structural and zircon U‐Pb SHRIMP study of the fold‐thrust belt and associated nepheline syenite plutons

Fe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks

Timing of Proterozoic metamorphism in the southern Curnamona Province: implications for tectonic models and continental reconstructions ∗

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