Chemical characters of volcanic rocks from Andaman ophiolite, India

Ray, K. K.; Sengupta, S.; Hul, H. J. Van Den

doi:10.1144/gsjgs.145.3.0393

Cited by 49 publications

(42 citation statements)

References 33 publications

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“…The geochemistry of the volcanic sequence of the Andaman ophiolite has previously been reported by Ray et al (1988). Whereas we report a larger number of trace elements that have been analysed by more refined analytical techniques, Ray et al (1988) analysed a larger number of samples.…”

Section: Geochemistry Of Volcanic Rocks and Basaltic Dykessupporting

confidence: 47%

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U–Pb zircon age of the Andaman ophiolite: implications for the beginning of subduction beneath the Andaman–Sumatra arc

Pedersen

Searle

Carter

et al. 2010

JGS

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The Andaman ophiolites form the basement of the Andaman Islands, which is a part of the outer forearc that links the Indo-Burma accretionary complex to the north with the Java-Sumatra trench-arc system to the SE. Upper mantle harzburgite and dunite are overlain by a cumulate peridotite-gabbro complex, highlevel intrusive rocks and a tholeiitic volcanic series. The upper crust in the South Andaman ophiolite shows also a prominent andesite-dacite volcanic suite, suggesting arc volcanism built onto ocean crust. U-Pb zircon dating of a trondhjemitic rock from Chiriya Tapu in South Andaman Island using laser ablation inductively coupled mass spectrometry reveals an age of crustal formation of 95 AE 2 Ma. The trondhjemites have geochemistry comparable with that of plagiogranites associated with ophiolite complexes, and å Nd values around +7 further confirm that they are derived from depleted mantle melts. Basaltic pillow lava and basaltic dykes that cut the trondhjemites have mid-ocean ridge basalt-like trace-element geochemistry. The new data show that the Andaman volcanic arc was built on Cenomanian ophiolite-oceanic crust and that subduction was initiated at this time along Tethys, at least from Cyprus through Oman to the Andaman Islands.

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Section: Geochemistry Of Volcanic Rocks and Basaltic Dykessupporting

confidence: 47%

“…Sheeted dykes have not been seen. A prominent dacite-andesite sequence is associated with basaltic, tholeiitic lavas on the east coast of South Andaman (Ray et al 1988). Radiolarian cherts and metalliferous umber sediments overlie volcanic rocks around Chiriya Tapu, South Andaman.…”

Section: Andaman Ophiolitesmentioning

confidence: 99%

U–Pb zircon age of the Andaman ophiolite: implications for the beginning of subduction beneath the Andaman–Sumatra arc

Pedersen

Searle

Carter

et al. 2010

JGS

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“…Smelvaer unit-mainly mafic volcaniclastic rocks (Vc) and pillow lavas (Pl) (see Furnes et al, 1990). tion-zone environment here consists of an inner active volcanic arc (Sumatra), a forearc region with active volcanoes (extending into Burma), and an outer ridge representing a well-developed accretionary prism (Ray et al, 1988). In the Andaman Sea model, the MORB chemical affinity of modern oceanic crust may or may not have a subduction-related geochemical fingerprint, and the volcaniclastic rocks intercalated with the sediments may represent pyroclastic debris associated with subduction-generated volcanism (Fig.…”

Section: Tectonic Environment Of Formation and Emplacement Of The Ophmentioning

confidence: 99%

Petrology, tectonics, and hydrothermal alteration of a fossil backarc oceanic crust: Solund-Stavfjord ophiolite complex of the western Norwegian Caledonides- A review

Furnes¹,

Skjerlie²,

Dilek³

2000

Ophiolites and Oceanic Crust: New Insights From Field Studies and the Ocean Drilling Program

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The Late Ordovician Solund-Stavfjord ophiolite complex in southwest Norway developed in a backarc basin through at least two episodes of seafloor spreading. The youngest phase is a structural domain (domain 1) in oceanic crust that formed along a backarc rift system that opened at an intermediate spreading rate and propagated north-northeastwardinto preexisting oceanic crust (domain 2). These two domains are separated by a 1-km-wide zone of anomalous oceanic crust, with fracture-zone affinity (domain 3), that is composed of strongly sheared gabbros and metabasalt dikes hosting abundant serpentinite bodies. Domains 1 and 2 contain high-level gabbro, sheeted dikes, a transition zone of dikes and volcanic rocks, and a volcanic suite consisting of various proportions of pillow lavas, massive lava flows, and hyaloclastite breccias. The metabasalts of both domains have MORB (mid-oceanic-ridge basalt) composition, with minor evidence of an island-arc component, and those of domain 1 are dominantly Fe-Ti basalts. Their contents of FeO t (total Fe as FeO), MgO, Al 2 O 3 , Cr, Ni, and Zr indicate that differences in depth of melting (30 to 12 kbar), crystal fractionation of olivine, plagioclase, and clinopyroxene at different levels in the mantle and crust (Ͻ8 kbar), and magma mixing controlled the composition of the metabasalts. The high proportion of massive lava flows, the lack of pervasive seafloor extensional tectonic deformation, and the hydrothermal history of the fossil oceanic crust in domain 1 are best comparable to the features of young oceanic crust of the Costa Rica Rift. The Solund-Stavfjord ophiolite complex is conformably overlain by (1) a heterogeneous suite (Stavenes Group) of quartz-dominated metasediments hosting pillow lavas, volcaniclastic rocks, and minor intrusions of island-arc tholeiite-like composition with a clear subduction signature (the Heggøy Formation) and (2) the supposedly later calc-alkalic and alkalic rocks of the Hersvik and Smelvaer units, respectively. This progressive change in chemical composition of the igneous rocks stratigraphically upward within the sedimentary cover indicates the development, through time, of a mature arc in the subduction-zone environment represented by the Solund-Stavfjord ophiolite complex. The mode and nature of magmatic, tectonic, and hydrothermal processes that operated during the evolution of the complex in a backarc basin are similar to those observed from modern mid-ocean ridge settings, particularly at intermediate-spreading ridge axes. The geologic features of the sedimentary cover of the Solund-Stavfjord ophiolite complex and the underlying Sunnfjord mélange suggest that the inferred Caledonian backarc basin evolved in proximity to a continental landmass, reminiscent of

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“…The Mentwai islands (south and west of Sumatra) are considered to be a southenly continuation of the AndamanNicobar trend. The Andaman-Nicobar group of islands form an arcuate chain extending for about 850 km bounded by latitude 6 • 45 N to 13 • 45 N and by longitude 92 • 15 E to 94 • 00 E. In several parts of south Andaman, ophiolite occurrences have been described by many researchers, viz., Haldar (1984), Ray et al (1988), Vohra et al (1989), Shastry et al (2001Shastry et al ( , 2002, Srivastava et al 2004 (figure 2). In some of these literatures, this ophiolite occurrence has been reported to be a dismembered ophiolite (Srivastava et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Complete preservation of ophiolite suite from south Andaman, India: A mineral-chemical perspective

et al. 2010

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Field studies supplemented by petrographic analyses clearly reveal complete preservation of ophiolite suite from Port Blair (11 • 39 N: 92 • 45 E) to Chiriyatapu (11 • 30 24 N: 92 • 42 30 E) stretch of South Andaman. The ophiolite suite reveals serpentinite at the base which is overlain unconformably by cumulate ultramafic-mafic members with discernible cumulus texture and igneous layering. Basaltic dykes are found to cut across the cumulate ultramafic-mafic members. The succession is capped by well exposed pillow basalts interlayered with arkosic sediments. Olivine from the basal serpentinite unit are highly magnesian (Fo 80.1-86.2 ). All clinopyroxene analyses from cumulate pyroxenite, cumulate gabbro and basaltic dyke are discriminated to be 'Quad' and are uniformly restricted to the diopside field. Composition of plagioclase in different lithomembers is systematically varying from calcic to sodic endmembers progressively from cumulate pyroxenite to pillow basalt through cumulate gabbro and basaltic dyke. Plagioclase phenocrysts from basaltic dyke are found to be distinctly zoned (An 60.7 -An 35.3 ) whereas groundmass plagioclase are relatively sodic (An 33 -An 23.5 ). Deduced thermobarometric data from different lithomembers clearly correspond to the observed preservation of complete ophiolite suite.

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Chemical characters of volcanic rocks from Andaman ophiolite, India

Cited by 49 publications

References 33 publications

U–Pb zircon age of the Andaman ophiolite: implications for the beginning of subduction beneath the Andaman–Sumatra arc

U–Pb zircon age of the Andaman ophiolite: implications for the beginning of subduction beneath the Andaman–Sumatra arc

Petrology, tectonics, and hydrothermal alteration of a fossil backarc oceanic crust: Solund-Stavfjord ophiolite complex of the western Norwegian Caledonides- A review

Complete preservation of ophiolite suite from south Andaman, India: A mineral-chemical perspective

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