Geochemistry of Precambrian mafic magmatic rocks of the Western Himalaya, India: petrogenetic and tectonic implications

Ahmad, Talat; Mukherjee, Pulok K.; Trivedi, J. R.

doi:10.1016/s0009-2541(99)00063-7

Cited by 71 publications

(56 citation statements)

References 38 publications

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“…Such large variation of Zr/Y discounts the possibility that they were all derived by fractional crystallization of a single parental magma. Here we suggest, different parental melts, representing different degrees of partial melting of same or similar mantle source(s) is a better proposition to explain the observed data (Ahmad et al, 1999). These different parental melts might have escaped the source region and fractionated independently, at various depths which may leads to the observed chemical variation in different subgroups or they have tapped heterogeneous source(s) (Ahmad et al, 1999).…”

Section: Incompatible Elements Ratio-ratio Plotsmentioning

confidence: 80%

“…Most of the samples plot between these two melting curves. There is subhorizontal shift of data points especially for the amphibolitic dykes away from the partial melting curve, this may indicate fractional crystallization of clinopyroxene ± olivine ± plagioclase (Floyd, 1993;Ahmad et al, 1999).…”

Section: Incompatible Elements Ratio-ratio Plotsmentioning

confidence: 99%

“…do not fractionate significantly during moderate degree of crystal fractionation of basaltic magma (Ahmad et al, 1999). Whereas these ratios are sensitive to variable degrees of partial melting of mantle sources or to different kinds of sources (Weaver and Tarney, 1981;Ahmad and Tarney, 1991;Petterson and Windley, 1992).…”

Section: Incompatible Elements Ratio-ratio Plotsmentioning

confidence: 99%

“…7A). Fractionation of plagioclase and olivine cannot alter the Zr/Y ratios, but fractionation of amphibole and clinopyroxene may raise the ratio with increasing Zr content (Floyd, 1993;Ahmad et al, 1999). There is large variation in Zr/Y ratios, especially for amphibolitic dykes.…”

Section: Incompatible Elements Ratio-ratio Plotsmentioning

confidence: 99%

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Geochemistry of mafic dykes in part of Chotanagpur gneissic complex: Petrogenetic and tectonic implications

Kumar

Ahmad

2007

Geochem. J.

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Chotanagpur Gneissic Complex basement rocks of the Eastern Indian shield has been dissected by numerous mafic dykes, now occurring as amphibolitic dykes and gneissic amphibolites. These dykes are subalkaline, ranging in composition from basalt through basaltic-andesite to andesite. These rocks have enriched incompatible trace element patterns. These are particularly enriched in light rare earth elements (LREE) and large ion lithophile elements (LILE) with depleted high field strength elements (HFSE; Nb, P, Ti) characterisitcs (i). Negative Sr anomaly is conspicuous. Nb/La and Nb/Ce ratios of the dykes are lower compared to the primitive mantle but these values are closer to average crustal values. Incompatible trace element data suggest enriched source characteristics and influence of crustal contamination in their genesis. Trace element ratios such as Gd/Yb of these dykes indicate at least two different sources. They probably represent Precambrian continental rifting in this region.

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Section: Incompatible Elements Ratio-ratio Plotsmentioning

confidence: 80%

Section: Incompatible Elements Ratio-ratio Plotsmentioning

confidence: 99%

Section: Incompatible Elements Ratio-ratio Plotsmentioning

confidence: 99%

Section: Incompatible Elements Ratio-ratio Plotsmentioning

confidence: 99%

See 2 more Smart Citations

Geochemistry of mafic dykes in part of Chotanagpur gneissic complex: Petrogenetic and tectonic implications

Kumar

Ahmad

2007

Geochem. J.

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“…It is also evident from the positive correlation (Fig. 7d) observed in these rocks between Zr/Y and Zr (cf., Floyd, 1993;Ahmad et al, 1999;Kumar and Ahmad, 2007). From the foregoing discussion it is envisaged that, the fractional crystallization as observed is considered to have occurred in the resultant hybrid magma, after the initial fractionation of the mafic melts during the partial melting of mantle source with an eclogite or garnet amphibolite residue.…”

Section: Magma-mixing and Fractional Crystallization Of Resultant Magmamentioning

confidence: 99%

Mantle-derived arc related mafic enclaves and host orthogneiss from the Shyok Suture Zone of NE Ladakh, India: An evidence of magma-mixing

Rao

Daga

Rai³

2013

Geochem. J.

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The Shyok valley in the northern Ladakh is a linear NW-SE trending suture zone (Shyok Suture Zone) and separates two distinct terranes, the southern continental margin of Eurasian Plate to north, and Ladakh magmatic arc to south. The crustal growth in the Shyok Suture Zone (SSZ) can be explained by two stage melting process involving the generation of orthogneiss (OG) with mafic enclaves (ME) (pre-collision), and temporal evolution towards increasingly more evolved felsic magmas during reworking processes (post-collision). In this paper, the geochemistry of various ME and host OG that fall within the Shyok-Darbuk corridor of the suture zone are discussed.The field, petrographic and geochemical data suggest that the ME and host OG are genetically related. The ME has formed by low degree of partial melting of a garnet-bearing source or from the partial melting of a basaltic source with a clinopyroxene-garnet eclogite as residue. The LILE and LREE enrichment of ME have been influenced by mantle-magma interaction during the passage of the hydrous primary arc-magma through the overlying lithosphere. The likely interpretation for the genetic linkage of ME and host OG is explained through the mixing of coeval mafic (enclave) and felsic melts, resulting in hybrid magma. Besides, several geochemical lines of evidence suggest that fractional crystallization of the resultant hybrid magma had played a complementary role in the evolution of these rocks.

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Zircon U‐Pb ages and Hf isotopes of the Askot klippe, Kumaun, northwest India: Implications for Paleoproterozoic tectonics, basin evolution and associated metallogeny of the northern Indian cratonic margin

et al. 2016

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Throughout the Himalayan thrust belt, klippen of questionable tectonostratigraphic affinity occur atop Lesser Himalayan rocks. Integrated U-Pb ages, Hf isotopic, and whole rock trace element data establish that the Askot klippe, in northwest India, is composed of Paleoproterozoic lower Lesser Himalayan rocks, not Greater Himalayan rocks, as previously interpreted. The Askot klippe consists of 1857 ± 19 Ma granite-granodiorite gneiss, coeval 1878 ± 19 Ma felsic volcanic rock, and circa 1800 Ma Berinag quartzite, representing a small vestige of a Paleoproterozoic (circa 1850 Ma) continental arc, formed on northern margin of the north Indian cratonic block. Detrital zircon from Berinag quartzite shows εHf 1850 Ma values between À9.6 and À1.1 (an average of À4.5) and overlaps with εHf 1850 Ma values of the Askot klippe granite-granodiorite gneiss (À5.5 to À1.2, with an average of À2.7) and other Paleoproterozoic arc-related Lesser Himalayan granite gneisses ( À4.8 to À2.2, with an average of À4.0). These overlapping data suggest a proximal arc source for the metasedimentary rocks. Subchondritic εHf 1850 Ma values (À5.5 to À1.2) of granite-granodiorite gneiss indicate existence of a preexisting older crust that underwent crustal reworking at circa 1850 Ma. A wide range of εHf 1850 Ma values in detrital zircon (À15.0 to À1.1) suggests that a heterogeneous crustal source supplied detritus to the northern margin of India. These data, as well as the presence of a volcanogenic massive sulphide deposit within the Askot klippe, are consistent with a circa 1800 Ma intra-arc extensional environment.

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Geochemistry of Precambrian mafic magmatic rocks of the Western Himalaya, India: petrogenetic and tectonic implications

Cited by 71 publications

References 38 publications

Geochemistry of mafic dykes in part of Chotanagpur gneissic complex: Petrogenetic and tectonic implications

Geochemistry of mafic dykes in part of Chotanagpur gneissic complex: Petrogenetic and tectonic implications

Mantle-derived arc related mafic enclaves and host orthogneiss from the Shyok Suture Zone of NE Ladakh, India: An evidence of magma-mixing

Zircon U‐Pb ages and Hf isotopes of the Askot klippe, Kumaun, northwest India: Implications for Paleoproterozoic tectonics, basin evolution and associated metallogeny of the northern Indian cratonic margin

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