Thermal history of Early Jurassic eclogite facies metamorphism in the Nagaland Ophiolite Complex, NE India: New insights into pre-Cretaceous subduction channel tectonics within the Neo-Tethys

Rajkakati, Mayashri; Bhowmik, Sumit; Ao, Aliba; Ireland, Trevor; Ávila, Janaína N.; Clarke, Graeme; Bhandari, Anubha; Aitchison, Jonathan C.

doi:10.1016/j.lithos.2019.105166

Cited by 19 publications

(36 citation statements)

References 95 publications

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“…The 200 km long and 5-15 km wide, NNE-trending NOC (Figure 2b) is different from other ophiolite bodies in the WOB by (a) the characteristic presence of an array of HP/LT metamorphic rocks from PD through LBS/EBS to Ep-EC and Hbl-EC facies in an ophiolitic mélange (Abdullah et al, 2020;Ao & Bhowmik, 2014;Bhattacharyya & Venkataramana, 1986;Bhowmik & Ao, 2016;Ghose & Singh, 1980;Rajkakati et al, 2019); (b) the association of metamorphic rocks with a disrupted oceanic plate sequence of chert, pillowed basalt, plagiogranite, mafic, and ultramafic cumulate and serpentinite (Figure 2b) (Acharyya, 1986); and (c) a general absence of widespread Upper Triassic flyschoidal sediments (cf. Pane Chaung Formation) and associated structurally underlying highly deformed and metamorphosed (cf.…”

Section: Geological Settingmentioning

confidence: 91%

“…The NOC includes metasedimentary rocks, dominantly of pelagic chert-limestone and minor greywacke association, with attenuated metabasalt, metagabbro, serpentinite, and pillow basalt with igneous texture and mineralogy (Acharyya, 1986;Ao & Bhowmik, 2014;Bhowmik & Ao, 2016). Metamorphic assemblages in the NOC reflect GS, PD, and blueschist to eclogite facies conditions (Figure 2b) (Abdullah et al, 2020;Ao & Bhowmik, 2014;Bhowmik & Ao, 2016;Rajkakati et al, 2019). Chatterjee and Ghose (2010)…”

Section: Geological Settingmentioning

confidence: 99%

“…The Nagaland Ophiolite Complex (NOC), North-east India, a Neo-Tethyan ophiolitic mélange lies at the south-eastern margin of the YTSZ, and at the northern extent of the Indo-Myanmar Ranges (Figure 1). The Complex preserves an array of HP metamorphic rocks from pumpellyite-diopside (PD) through lawsonite blueschist/epidote blueschist (LBS/EBS) to hornblende-eclogite (Hbl-EC) and to epidote eclogite (Ep-EC) facies (Abdullah, Misra, Sarvesha, & Ghosh, 2020;Ao & Bhowmik, 2014;Bhattacharyya & Venkataramana, 1986;Bhowmik & Ao, 2016;Ghose, Agrawal, & Chatterjee, 2010;Ghose & Singh, 1980;Rajkakati et al, 2019). These metamorphic rocks are tectonically interlayered with a sequence of mantle peridotite tectonites, mostly serpentinized, mafic and ultramafic cumulates, high-level plutons of quartz dolerite to plagiogranite composition and a mildly metamorphosed pillowed basalt-limestone/ marble-ferruginous and radiolarian chert association, representing the F I G U R E 1 A tectonic map of eastern Tibet, South-east China, Myanmar, and North-east India showing the locations of different Tethyan sutures (BNS, Bangong-Nujiang Suture; LCS, Longmu Co-Shuanghu Suture; YTS, Yarlung-Tsangpo Suture), oceanic blueschists, and amphibolites (1-4) along the YTS zone, Indo-Myanmar Range (IMR), and Western, Central, and Eastern Ophiolite belts (WOB, COB, and EOB) in the tectonic framework of Indian, Asian, and Myanmar plates/microplates (modified after Searle et al, 2007;, Bhowmik & Ao, 2016.…”

Section: Introductionmentioning

confidence: 99%

“…Others, including serpentinized spinel lherzolites at the base of the NOC and metabasalts reveal their derivations from a Mid-Oceanic Ridge (MOR) setting (Ao et al, 2020;Bhowmik & Dutta, 2021;Ghosh et al, 2018). Although metamorphic P-T path information of some of these blueschists and eclogites is now available and reveals a complex burial-exhumation and heating-cooling history in the Nagaland subduction channel (Ao & Bhowmik, 2014;Bhowmik & Ao, 2016;Rajkakati et al, 2019), these are not well integrated with the Nagaland accretionary complex. There is also ongoing debate on the age information of the NOC (e.g., Late Triassic to Early Jurassic, Rajkakati et al, 2019;Middle Jurassic, Aitchison et al, 2019;Late Jurassic, Baxter, Aitchison, Zyabrev, & Ali, 2011;Sarkar et al, 1996 or even Cretaceous).…”

Section: Introductionmentioning

confidence: 99%

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Tectonic framework of the high‐pressure metamorphic rocks of the Nagaland Ophiolite Complex, North‐east India, and its geodynamic significance: A review

Bhowmik

Rajkakati

2021

Geological Journal

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In this study, we made a review of the published metamorphic and geochronological data of an array of high-pressure metamorphic rocks from the Nagaland Ophiolite Complex, North-east India, and present them in the tectonic framework of two temporally separate subduction systems within the eastern arm of the Neo-Tethys. The metamorphic rocks are studied in terms of three structural units. The structurally lowermost Mokie-Satuza-Thewati (MST) unit shows a metamorphic zonation from greenschist through pumpellyite-diopside (T Max ~335 C at ~6 kbar) to lawsonite blueschist (T Max ~340 C at ~11.5 kbar) to epidote eclogite (T Max ~550-660 C at ~24 kbar in Mokie to T Max ~630 C at ~26-28 kbar in Thewati localities) facies structurally upward. Both the blueschists and eclogites record a clockwise (CW) P-T path of evolution. We relate the low apparent thermal gradient at the metamorphic peak (7-9 C/km), the steep dP/dT slope of the metamorphic field gradient, the general CW metamorphic P-T paths, and the published U-Pb zircon dates in the eclogites (between ca. 205 and ca. 172 Ma) and radiolarian biostratigraphy data in the MST metamorphic sequence with the development of a Late Triassic to Middle Jurassicaged cold mature stage of an intra-oceanic subduction system within the Neo-Tethys. This is considered to be one of the oldest in the Yarlung-Tsangpo Suture Zone. The metamorphosed uppermost part of the structurally intermediate unit, named the Moya-Salumi (MS) sequence, consists of a structurally upper hornblendeeclogite (Hbl-EC) to epidote amphibolite facies subunit and a lower epidote blueschist (EBS) facies subunit. The eclogite subunit is polyphase metamorphosed (Hbl-EC facies M 1 with T Max ~625 C at ~13.8 kbar and garnetiferous EBS facies M 2 with T Max ~540 C at ~14.4 kbar) with both the events recording counterclockwise P-T paths. The monocyclic EBS facies subunit, on the other hand, has a memory of the M 2 cycle of metamorphism only. We relate this combined M 1 -M 2 cycles of metamorphism in the MS sequence to a second oceanic subduction beneath the continental Naga Metamorphics, the latter constituting the structurally uppermost unit. The metamorphic pulses together reflect progressive cooling of the second subduction channel from an initially warm stage during subduction infancy to a later cold mature stage of subduction. The different metamorphic rocks in the MST and MS units reveal architectures of two temporally separate accretionary complexes. Their present occurrence as a tectonic collage is likely to be the product of the Eocene collision of the Indian and the Myanmar plates.

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Section: Geological Settingmentioning

confidence: 91%

Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tectonic framework of the high‐pressure metamorphic rocks of the Nagaland Ophiolite Complex, North‐east India, and its geodynamic significance: A review

Bhowmik

Rajkakati

2021

Geological Journal

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“…In the Naga Hills of northeastern India, limestone and metasedimentary rocks of the early Paleozoic‐Mesozoic Naga Metamorphics are thrust to the northwest atop the Early Cretaceous‐Eocene Nagaland Ophiolitic Complex and late Eocene‐Oligocene Jopi‐Phokphur Formation (Aitchison et al, 2019; Brunnschweiler, 1966; Chatterjee & Ghose, 2010). The Nagaland Ophiolitic Complex is notable for containing blueschist and eclogite blocks with Early Jurassic peak metamorphic ages, which have been interpreted to reflect the earliest phase of Neo‐Tethys subduction beneath the West Burma block (Rajkakati et al, 2019). The Naga Ophiolitic Complex and Jopi‐Phokphur Formation are thrust to the northwest atop the Late Cretaceous‐Eocene Disang Flysch (Chatterjee & Ghose, 2010).…”

Section: Geological Settingmentioning

confidence: 99%

Structural and Thermochronologic Constraints on the Cenozoic Tectonic Development of the Northern Indo‐Burma Ranges

et al. 2020

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The~1,500-km-long, north trending Eastern Flanking Belt of the Himalayan-Tibetan orogenic system is located along the eastern margin of the Indian subcontinent. Although the belt is a key element of the Cenozoic India-Asia collisional zone, its tectonic evolution remains poorly understood. This lack of knowledge has impacted our ability to differentiate between competing hypotheses for the evolution of the India-Asia collision. To address this problem, we integrate constraints on the structural framework and magnitude of Cenozoic shortening strain with thermochronology of the northernmost segment of the belt located directly southeast of the eastern Himalayan syntaxis (i.e., the northern Indo-Burma Ranges). The study area exposes a southwest directed thrust belt that is bounded by the Indian craton in the west and the right-slip Jiali fault zone in the east. New and existing (U-Th)/He and 40 Ar/ 39 Ar thermochronologic data indicate that thrust-related cooling occurred from~36 Ma in the northeast to~5.6 Ma in the southwest. Episodes of out-of-sequence thrusting occurred at~30-20,~14-12, and~11-6 Ma within the thrust belt. Restoration of the thrust belt yields a minimum horizontal shortening of~280 km (~86%). These results combined with (1) the recorded local absence of several major Himalayan-Tibetan lithologic units (i.e., Tethyan Himalayan Sequence, Greater Himalayan Sequence, and southern Gangdese batholith) and (2) the southward decrease in the thrust-belt width (33-5 km) suggest a complex history of thrusting in the northern Indo-Burma Ranges and an spatial increase in Cenozoic crustal shortening and/or continental underthrusting from west to east across the eastern Himalayan syntaxis.

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Petrogenesis of mantle peridotite and cumulate peridotite rocks from the Nagaland Ophiolite Complex, NE India

Satyanarayanan

2021

Geological Journal

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Here, we report new geochemical data from mantle peridotite (spinel lherzolite, dunite, and harzburgite) and cumulate peridotite (websterite) rocks from the northernmost portion of the Nagaland Ophiolite Complex. Based on detailed textural, mineral (major element) chemistry, and whole-rock (major and trace element) chemistry, we reveal the origin of these rocks in different tectonic settings and their modification via the melt-mantle interaction process. The spinel lherzolite rocks with low Cr# (0.16-0.25) chrome spinel are mantle residues formed after low degrees ($10-15%) of partial melting in a mid-oceanic ridge setting, which has been subsequently modified in a subduction zone setting. However, the dunites and harzburgite samples are interpreted to be depleted mantle residue formed in a supra-subduction zone (SSZ) setting. Additionally, the dunites are inferred to be of replacive origin representing former harzburgites. Based on Cr# of chrome spinel, the dunites are classified into low Cr# (0.53-0.57), medium Cr# (0.73-0.79), and high Cr# (0.89-0.90) dunites. High Cr# dunite with low-TiO 2 (0.01-0.06 wt%) possibly formed by interaction with a boninitic melt, whereas low-medium Cr# dunite with high TiO 2 (0.14-0.34 wt%) formed by interaction with a high-Ti melt in an SSZ setting. Harzburgite samples with their highly resorbed orthopyroxene grain boundaries contain chrome spinels (Cr# = 0.84-0.88; TiO 2 = 0.00-0.06 wt%) similar to the high Cr# dunite samples and are also interpreted to be formed by interaction with a boninitic melt. The websterite samples with their low Mg# (0.79) olivine and low Ni (345-413 ppm) content are interpreted to be of cumulate origin formed in an SSZ setting. However, the interstitial chrome spinel blebs with low Mg# (0.18-0.19), high Cr# (0.60-0.61), Fe 3+ (0.20-0.21), and very high TiO 2 (2.03-2.04 wt%) are interpreted to be a result of post-cumulus interaction of interstitial chrome spinel with high-Ti intercumulus melt.These mantle peridotites and cumulates of different tectonic origins were obducted and juxtaposed during the final stages of the India-Asia collision.

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Thermal history of Early Jurassic eclogite facies metamorphism in the Nagaland Ophiolite Complex, NE India: New insights into pre-Cretaceous subduction channel tectonics within the Neo-Tethys

Cited by 19 publications

References 95 publications

Tectonic framework of the high‐pressure metamorphic rocks of the Nagaland Ophiolite Complex, North‐east India, and its geodynamic significance: A review

Tectonic framework of the high‐pressure metamorphic rocks of the Nagaland Ophiolite Complex, North‐east India, and its geodynamic significance: A review

Structural and Thermochronologic Constraints on the Cenozoic Tectonic Development of the Northern Indo‐Burma Ranges

Petrogenesis of mantle peridotite and cumulate peridotite rocks from the Nagaland Ophiolite Complex, NE India

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