Depositional environment and tectonic backdrop of meta-carbonates in the Eastern Himalayan ophiolites, India: insights from calcite microstructures, whole-rock elements and stable isotopes

Dutt, Amrita; Singh, Alka; Oinam, Govind; Srivastava, Rajesh K.

doi:10.1007/s13146-021-00704-x

Cited by 6 publications

(3 citation statements)

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“…The ITSZ turning sharply south‐eastward at the eastern Himalayan syntaxis is offset northward by the Sagaing Fault and continues southward along the IMOB (Gansser, 1980) (Figure 1a). The ophiolite sequences occurring all along the Tuting‐Tidding Suture Zone, which runs east of the Siang Antiform have been considered as the south‐eastern extension of the ITSZ (Dutt, Singh, Oinam, & Srivastava, 2021; Dutt, Singh, Srivastava, & Oinam, 2021; Dutt, Singh, Srivastava, Oinam, & Bikramaditya, 2021; Singh et al, 2021; Singh & Singh, 2011, 2013). The suture zone further extends south to the IMOB and the Andaman‐Nicobar Island Arc (Chaubey et al, 2022; Imtisunep et al, 2022; Khogenkumar et al, 2016, 2021; Premi et al, 2022; Singh, 2009; Singh, 2013; Singh et al, 2012; Singh et al, 2013; Singh, Nayak, et al, 2017).…”

Section: General Geologymentioning

confidence: 99%

Stable isotope geochemistry and microfossil assemblages of carbonate rocks in the ophiolite mélange zone of the Indo–Myanmar orogenic Belt, NE India: Implications on age and depositional environment

et al. 2022

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A comprehensive data of whole‐rock and stable isotopic geochemistry along with microfossil assemblages of the carbonate rocks of the ophiolite mélange zone of the Indo–Myanmar orogenic Belt (IMOB), north‐east India are discussed, to determine the influence of terrigenous contamination during the formation of these carbonate rocks and also to understand their depositional environment and ages. These carbonate rocks contain a diverse fauna with the dominance of foraminiferal assemblages of planktonic foraminifera (Globotruncana sp. and Heterohelix sp., etc.) which indicates they were formed during the Santonian to Maastrichtian age. Based on chemical compositions, these carbonate rocks have been identified as limestone (CaO/MgO > 50.1) to slightly dolomitic limestone (9.1 < CaO/MgO < 50.1). Total rare earth element (REE) contents in these carbonates are variable (22.39–146.05 ppm). The Post‐Archean Australian Shale (PAAS)‐normalized REE + Y patterns of these carbonates exhibit seawater‐like REE patterns with LREE depletion and relative HREE enrichment with negative Ce anomalies (Ce/Ce* = 0.32–0.79) and positive Y (4.42–27.81 ppm) and Eu anomalies (Eu/Eu* = 1.11–1.86), suggesting that they were deposited under an oxygenated environment with contamination by hydrothermal activity. They are also depleted in δ13C 0/00 (PDB) (1.02–1.570/00) and δ18O 0/00 (PDB) (−6.37 to −9.00%) values which characterize marine precipitates. Eu anomalies and spread in negative δ18O 0/00 (PDB) values to a lesser extent of δ13C 0/00 (PDB) values of these carbonates suggest their formation was altered by diagenesis in the shallow marine environment. Our new whole‐rock and stable isotope geochemical characteristics, in conjunction with microfacies, suggest that the investigated carbonate rocks might have been formed in low‐energy environments, and deposited in neritic to bathyal palaeoenvironments during the Santonian to Maastrichtian interval.

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Section: General Geologymentioning

confidence: 99%

Stable isotope geochemistry and microfossil assemblages of carbonate rocks in the ophiolite mélange zone of the Indo–Myanmar orogenic Belt, NE India: Implications on age and depositional environment

et al. 2022

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“…Application of major, trace and rare earth elements (REE) as geochemical proxies is gaining wide acceptance in carbonate provenance studies and the environmental settings during carbonate deposition/precipitation (Banner et al 1988a, b;Kamber and Webb. 2001;Nothdurft et al 2004;Frimmel 2009;Nagarajan et al 2011;Azomani et al 2013;Zhao and Jones 2013;Zhao and Zheng 2014;Li et al 2017;Srivastava and Singh 2019;Guruaribam et al 2021) and post-depositional alteration (Delpomdor et al 2013;Nagarajan et al 2013;Wang et al 2014;Franchi et al 2015;Ganai et al 2018;Dutt et al 2021). This paper presents petrographic, mineralogical and geochemical data, regarding which discussion on the occurrences of polyphase dolomite geobodies, examination of the strata and structural controls are attempted.…”

Section: Introductionmentioning

confidence: 95%

Geochemical evolution of structure-bedding controlled hydrothermal dolomites of the Kinta Valley, Western Malaysia

Hui

Nagarajan

Ramkumar

et al. 2022

Carbonates Evaporites

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Study of secondary dolomitization and documentation of the evolution of basinal fluids and host rock, especially that of fine-grained deepwater carbonate mudstone are of interest toward of reservoir characterization. From this perspective, field characteristics in relation to mineralogy, petrography and geochemistry of the Paleaozoic carbonates of the Kinta Valley, Peninsular Malaysia, were investigated and documented. A total of 33 samples were collected across the various degree of dolomitization and analyzed for their petrographic properties (n = 55), while mineralogical and geochemical compositions (n = 33) were analyzed using XRD, ICP and ICPMS analysis, respectively. These analyses were performed to elucidate the diagenetic events, episodic dolomitization and development of fluid evolution as a function of regional tectono-thermal events during the Permian to Cenozoic. It is interpreted that the host calcareous mudstones (HCMs) were deposited in oxygenated, open marine seawaters. The studied samples retain the original seawater characteristics despite negligible, minor alterations of REE characteristics due to diagenesis and detrital input. Though the concentrations and trends of REEs of the dolomitic facies are modified to a certain extent, their affinities with HCMs are preserved. Enrichments of Mg, Mn, Na and depletion of Sr are linked to the effect of dolomitization under the open system of diagenesis. The redox conditions fluctuated to show distinct, recognizable variations between different dolomite phases. The MREE enrichments with other trace elements such as Mn, Fe and low Sr content indicate the association of diagenetic fluids with deep-circulating crustal hydrothermal fluids. Hydrothermal influence has been recorded along the fractures, which might have originated from the sub-surface litho units and facilitated episodic dolomitization, especially during significant tectono-thermal events. This study affirms that the occurrence, geochemical and mineralogical evolution of the dolomites of the Kinta Valley were controlled by magmatic events, whereas the intensity of replacement dolomitization was controlled by host rock texture, varied bulk chemistry of host rock, circulating fluid and temperature.

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“…Normalizing REE compositions are afterSun and McDonough (1989).subducting slab where they underwent two stages of metamorphism and were accreted at the base of the ophiolites as their metamorphic sole(Dutt, Singh, Srivastava, & Oinam, 2021a). Precipitation of carbonates in the highly saline subduction zone occurred during this time in the mature forearc(Dutt, Singh, Oinam, & Srivastava, 2021c). A third stage of the tectonic model of the Arunachal ophiolites was identified by the low-temperature metamorphism of the complete ophiolite unit (peridotite + intrusive + amphibolite + carbonate) during its accretion and exhumation after the freezing of the forearc(Singh et al, 2022a).…”

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confidence: 99%

Petrogenesis of mantle peridotites in Neo‐Tethyan ophiolites from the Eastern Himalaya and Indo‐Myanmar Orogenic Belt in the geo‐tectonic framework of Southeast Asia

2022

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The Neo‐Tethyan ophiolites of the Tuting‐Tidding Suture Zone (TTSZ), Eastern Himalaya (viz., Tidding Ophiolite Complex and Mayodia Ophiolite Complex) and Indo‐Myanmar Orogenic Belt (IMOB, i.e., Nagaland Ophiolite Complex and Manipur Ophiolite Complex) which lie along the southern extension of the Indus‐Tsangpo Suture Zone have been collectively investigated through the mantle‐derived peridotite sequence. The peridotites (harzburgite and dunites) in the Eastern Himalaya ophiolites are refractory, constrained by the high Fo olivine content (~95), high Cr# [Cr/(Cr + Al)] (0.90–0.99), as well as by the parental melt composition of Cr‐spinels (Al2O3 melt = 3.05–7.55 wt%, FeO/MgO = 0.69–6.46). They have slightly “U‐shaped” chondrite‐normalized Rare Earth Elements (REE) patterns with slight enrichment in Light Rare Earth Elements (LREE) relative to the patterns expected for residues of partial melting, thereby indicating a reaction with the LREE‐enriched melt. These peridotites represent residual portions of a depleted/enriched mantle that underwent partial melting up to 23% in the nascent forearc of an intra‐oceanic subduction zone, and later metasomatized by high‐temperature silicate melts and low‐temperature hydrous fluids. They are composed of a very refractory olivine‐spinel assemblage (Fo: 91.68–96.44; Cr#: 0.90–0.99), corroborating a boninitic parentage, with influence from melt‐rock interactions. In the case of the IMOB ophiolites, a wide range of chemical compositions is observed in the mantle sequence. Lherzolites display low Cr# (0.12–0.26) and TiO2 (<0.11) associated with high Mg# [Mg/(Mg + Fet)] (0.69–0.76) in the Cr‐spinels present in them. They represent the residual product of a fertile mantle that underwent low‐degree partial melting (2%–10%) in a divergent mid‐ocean ridge (MOR) tectonic setting. On the other hand, the harzburgites and dunites of the IMOB have high Cr# (0.84–0.90) and low TiO2 (<0.06 wt%) Cr‐spinels and exhibit slightly U‐shaped REE distributions indicating their derivation from a highly depleted mantle source, which experienced higher degree partial melting (17%–24%) similar to those of supra‐subduction zone (SSZ) harzburgites and dunites of the TTSZ peridotites. The occurrence of both MOR and SSZ types of melting regimes indicates that the peridotites in the IMOB ophiolites formed at two major different stages of the pre‐subduction and subduction events, respectively. However, the peridotites of Eastern Himalaya ophiolites were formed only during subduction tectonics. Thus, we argue that the mantle peridotites in the ophiolites of northeast India evolved from lherzolite through clinopyroxene‐harzburgite and harzburgite then to highly refractory dunite, supporting multistage melting and melt‐rock reaction processes during their generation.

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Depositional environment and tectonic backdrop of meta-carbonates in the Eastern Himalayan ophiolites, India: insights from calcite microstructures, whole-rock elements and stable isotopes

Cited by 6 publications

References 81 publications

Stable isotope geochemistry and microfossil assemblages of carbonate rocks in the ophiolite mélange zone of the Indo–Myanmar orogenic Belt, NE India: Implications on age and depositional environment

Stable isotope geochemistry and microfossil assemblages of carbonate rocks in the ophiolite mélange zone of the Indo–Myanmar orogenic Belt, NE India: Implications on age and depositional environment

Geochemical evolution of structure-bedding controlled hydrothermal dolomites of the Kinta Valley, Western Malaysia

Petrogenesis of mantle peridotites in Neo‐Tethyan ophiolites from the Eastern Himalaya and Indo‐Myanmar Orogenic Belt in the geo‐tectonic framework of Southeast Asia

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