K-Rb relations in the alkaline suites of the Eastern Ghats precambrian belt, India

Bose, Mihir K.; Roy, Asish K. Ghosh; Czygan, Wolfgang

doi:10.1016/s0024-4937(82)80007-8

Cited by 5 publications

(2 citation statements)

References 19 publications

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“…This assumption is based on the general geochemical characters ofthe syenite including high transition element levels and K/Rb ratios. This assumption is substantiated by observations made on similar alkalic plutons of Kerala region (Nair and Santosh 1984a, b;Santosh and Nair 1985) as well as from the adjacent terrains (Bose et al 1982). Moreover, the syenite is emplaced along an active fault-lineament which has probable extension to mantle-depths like other fault-lineaments of the region (Santosh and Sankar 1984).…”

Section: Petrogenesismentioning

confidence: 70%

The Mannapra syenite, Central Kerala, India: Geochemistry, petrogenesis and bearing on anorogenic magmatism

Santosh

1985

J Earth Syst Sci

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Occurrence of a syenite body near Mannapra, Trichur district, Kerala, is reported. The syenite, emplaced within charnockitic country rocks along the Idamalayar faultlineament, is exposed over an area of 8 km 2. The rock, classified as quartz alkali feldspar syenite based on Q-A-P proportions, has alkali feldspar as the dominant mineral constituent which shows variation in perthitic texture from r to micro-and patch-perthites. Both ortho-and clino-pyroxenes are present, with the former showing blebs of plagioclase suggesting Al-unmixing. Clinopyroxene shows subsolidus reequilibration with greenish pleochroic grain margins and local conversion to alkali amphibole. The petrochemical characters indicate that the syenite crystallized from a partial melt which equilibrated from Krich, Rb-depleted source in the upper mantle, in response to crustal distension and mantle degassing prior to the rifting of the continent. Reaction between early formed minerals and the late peralkaline liquid towards the residual phase resulted in subsolidus reequilibration textures. The syenite is envisaged to be yet another example of the manifestation ofanorogenic magmatism in this part of the Indian shield.

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Section: Petrogenesismentioning

confidence: 70%

The Mannapra syenite, Central Kerala, India: Geochemistry, petrogenesis and bearing on anorogenic magmatism

Santosh

1985

J Earth Syst Sci

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“…Sarkar et al 1981), although the element trends described by the Chilka Lake anorthositeleuconorites are slightly shifted compared to their counterparts at Turkel. It stands to reason, therefore, that the comagmatic nature of the low-K anorthositeleuconorite suite and the high-K quartz monzonitegranite suite as advocated for the Chilka Lake by Sarkar et al (1981) and tacitly assumed for the Eastern Ghats massif anorthosite complexes in general by Bose (1979) and Leelanandam and Narsimha Reddy (1988) is not tenable. It also follows that the validity of the isochron determined by Sarkar et al (1981) for the Chilka Lake complex is open to scrutiny.…”

Section: Petrogenetic Considerationsmentioning

confidence: 98%

The Turkei anorthosite complex revisited

Maji

Bhattacharya

Raith

1997

Proc. Indian Acad. Sci. (Earth Planet Sci.)

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Geological investigation in recent years reveals that the anorthosite-leuconorite massif (81 sq km) is much larger than known from previous studies. The massif is bordered by a suite of garnetiferous felsic rocks comprising quartz monzonite gneiss, granite gneiss and megacrystic K-feldspar-bearing granite. Ferrodiorites, hitherto unknown from this area, occur as veins at the massif-felsic suite interface, and as rare apophyses within leuconorites at the massif margin. The massif and the bordering felsic rocks were presumably emplaced during the earliest of the three phases of folding documented by the metasedimentary gneisses that host the massif.The petrographic and geochemical characteristics suggest that the low-K anorthosite-leuconoriteferrodiorite suite does not share a common parentage with the bordering high-K felsic intrusives. The anorthosites and leuconorites were derived by polybaric fractionation of mantle-derived melts. The ferrodiorites are anorthosite residual melts that were not entirely segregated from the host solids. By contrast, the granite gneisses and granites originated by incongruent melting of crustal rocks. The chemical differences between quartz monzonite and granite gneisses point to their derivation from different crustal precursors.82"155' 8310' 83"15' 83"1,0'9 "" / /

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Inter-element relations in some alkaline suites of the Eastern Ghats Precambrian belt

Bose

Maitra

Roy

1984

Proc. Indian Acad. Sci. (Earth Planet Sci.)

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K-Rb relations in the alkaline suites of the Eastern Ghats precambrian belt, India

Cited by 5 publications

References 19 publications

The Mannapra syenite, Central Kerala, India: Geochemistry, petrogenesis and bearing on anorogenic magmatism

The Mannapra syenite, Central Kerala, India: Geochemistry, petrogenesis and bearing on anorogenic magmatism

The Turkei anorthosite complex revisited

Inter-element relations in some alkaline suites of the Eastern Ghats Precambrian belt

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