Segmentation and morphology of the Central Indian Ridge between 3°S and 11°S, Indian Ocean

Raju, K. A. Kamesh; Samudrala, Kiranmai; Drolia, R. K.; Amarnath, Dileep; Ramachandran, R.; Mudholkar, Abhay

doi:10.1016/j.tecto.2012.06.001

Cited by 30 publications

(15 citation statements)

References 49 publications

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“…Rifting and oceanic drifting was plausibly influenced by pre-existing tectonic structures inherited by the Varisic orogeny (Manatschal et al [104]; Gilard et al [105]), giving rise to a very complex paleogeography with many ridge offset and short zigzags accommodating seafloor accretion as observed in modern oceanic sectors characterized by slow spreading (Grindlay et al [106]; Lazar et al [107]; Kamesh Raju et al [108]; Murton and Rona, [109]; Mercier de Lèpinay et al [110]). …”

Section: Discussionmentioning

confidence: 99%

The Betic Ophiolites and the Mesozoic Evolution of the Western Tethys

et al. 2017

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Abstract:The Betic Ophiolites consist of numerous tectonic slices, metric to kilometric in size, of eclogitized mafic and ultramafic rocks associated to oceanic metasediments, deriving from the Betic oceanic domain. The outcrop of these ophiolites is aligned along 250 km in the Mulhacén Complex of the Nevado-Filábride Domain, located at the center-eastern zone of the Betic Cordillera (SE Spain). According to petrological/geochemical inferences and SHRIMP (Sensitive High Resolution Ion Micro-Probe) dating of igneous zircons, the Betic oceanic lithosphere originated along an ultra-slow mid-ocean ridge, after rifting, thinning and breakup of the preexisting continental crust. The Betic oceanic sector, located at the westernmost end of the Tethys Ocean, developed from the Lower to Middle Jurassic (185-170 Ma), just at the beginning of the Pangaea break-up between the Iberia-European and the Africa-Adrian plates. Subsequently, the oceanic spreading migrated northeastward to form the Ligurian and Alpine Tethys oceans, from 165 to 140 Ma. Breakup and oceanization isolated continental remnants, known as the Mesomediterranean Terrane, which were deformed and affected by the Upper Cretaceous-Paleocene Eo-Alpine high-pressure metamorphic event, due to the intra-oceanic subduction of the Jurassic oceanic lithosphere and the related continental margins. This process was followed by the partial exhumation of the subducted oceanic rocks onto their continental margins, forming the Betic and Alpine Ophiolites. Subsequently, along the Upper Oligocene and Miocene, the deformed and metamorphosed Mesomediterranean Terrane was dismembered into different continental blocks collectively known as AlKaPeCa microplate (Alboran, Kabylian, Peloritan and Calabrian). In particular, the Alboran block was displaced toward the SW to occupy its current setting between the Iberian and African plates, due to the Neogene opening of the Algero-Provençal Basin. During this translation, the different domains of the Alboran microplate, forming the Internal Zones of the Betic and Rifean Cordilleras, collided with the External Zones representing the Iberian and African margins and, together with them, underwent the later alpine deformation and metamorphism, characterized by local differences of P-T (Pressure-Temperature) conditions. These Neogene metamorphic processes, known as Meso-Alpine and Neo-Alpine events, developed in the Nevado-Filábride Domain under Ab-Ep amphibolite and greenschists facies conditions, respectively, causing retrogradation and intensive deformation of the Eo-Alpine eclogites.

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Section: Discussionmentioning

confidence: 99%

The Betic Ophiolites and the Mesozoic Evolution of the Western Tethys

et al. 2017

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“…The geophysical survey showed that this section of slow spreading CIR has several smaller segments bounded by transform faults and nontransform discontinuities (Drolia et al, ; Kamesh Raju et al, ). Due to substantial magmatic accretion, some of these segments developed shallow zones (depth <2,000 m) termed as megamullian structures or ridge‐transform intersection (RTI) highs (Kamesh Raju et al, ; Kiranmai, Kamesh Raju, & Rama Rao, ). During the same cruise, near 06°38.5′S and 68°19.34′E, an RTI high on a 74.4‐m‐long ridge segment at water depth ~2,700 m was mapped (Figure ) sampled for rock by using a chain bag dredge.…”

Section: Methodsmentioning

confidence: 99%

Geochemical, mineralogical, and Sr–Nd isotopic compositions of ferromanganese encrustations from Central Indian Ridge at 06°38.5′S

et al. 2017

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Mineralogical, geochemical, and isotopic (Sr and Nd) studies of 14 ferromanganese encrustations on basaltic substrates from Central Indian Ridge at 06°38.5′S indicate that except for two (NC3 and NC4), the samples are hydrogenous type. NC3 and NC4 have slightly higher growth rates, lower bulk trace metal contents, and low ∑REE. They have a lower content of high field strength (e.g., Hf, Ta, Zr, and Nb), incompatible (e.g., Pb, Th, and U), and lithophilic elements (e.g., Sr and Ba) than others. In addition, NC3 has a lower 87Sr/86Sr ratio (0.708825) than the remaining samples (range 0.709169–0.709253) but higher 143Nd/144Nd ratio (0.512296) than others (range 0.512258–0.512279). Both NC3 and NC4 have a higher radiogenic component indicated by their low εNd value (−6.67) than the remaining samples (range −7.00 to −7.41). These evidences together indicate a possible contribution of trace metals by a local mixed source of hydrothermal and hydrogenous origin during their growth history.

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“…Tucholke et al () documented that OCCs are most common at slow spreading rates (14–32 mm/year), suggesting that some critical spreading rate may exist above which OCCs rarely develop. Indeed, OCCs frequently occur along both the northern Mid‐Atlantic Ridge (e.g., Cann et al, ; Escartín et al, ; Macleod et al, ; Smith et al, ; Tucholke & Lin, ) and the Central Indian Ridge where spreading rates are up to ~33 mm/year (Kamesh Raju et al, ). A critical spreading rate of about 30 mm/year is further supported by this study.…”

Section: Discussionmentioning

confidence: 99%

“…Examples include two segmented transform faults of the Central Atlantic, the St Paul transform fault (Maia et al, 2014(Maia et al, , 2016 and the Ascencion transform fault (Brozena & White, 1990;Ohara et al, 2011). OCCs also commonly occur along the series of short ridge segments and long transform faults of the Central Indian Ridge where spreading rates are~35 mm/year (Kamesh Raju et al, 2012). Because intratransform spreading segments are bounded on both sides by thick, cold lithospheric plates, the resulting "transform fault effect" is expected to depress the height of the melting regime (e.g., Langmuir & Forsyth, 2007) as well as its width (e.g., Ligi et al, 2005) along the entire length of these short spreading segments.…”

Section: Influence Of Transform Fault Length On Melt Supply At Leadinmentioning

confidence: 99%

Distinctive Seafloor Fabric Produced Near Western Versus Eastern Ridge‐Transform Intersections of the Northern Mid‐Atlantic Ridge: Possible Influence of Ridge Migration

Cormier

Sloan

2019

Geochem Geophys Geosyst

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Multibeam bathymetry compiled along fracture zones of the northern Atlantic reveals a striking morphological asymmetry. Seafloor fabric produced at western ridge‐transform intersections (RTIs) tends to consist of linear ridges, small in amplitude, and regularly spaced, and oceanic core complexes (OCCs) occur infrequently. In contrast, seafloor fabric produced at eastern RTIs is more irregular and blocky and displays characteristics usually associated with melt‐poor accretion: These include more than double the occurrence of OCCs as well as greater seafloor depths, even where seafloor is younger than that on the opposite side of the fracture zone. We propose that this asymmetry is a consequence of the westward migration of the Mid‐Atlantic Ridge. Such migration is expected to result in an enhanced melt supply at leading (western) RTIs compared to trailing (eastern) RTIs. The morphological asymmetry is observed for ridge offsets of ~40 to ~200 km, a range that may be related to the width of melting regimes that supply ridge segments. At slow spreading ridges, contrasting melt supplies across fracture zones may therefore be best expressed in the distinct seafloor fabrics preserved beyond the dynamically maintained relief of the axial rift valley and walls rather than in the contrasting axial depths documented for faster spreading ridges. Although OCCs appear to form preferentially at spreading rates lower than 30 mm/year, their common occurrence along the northern Mid‐Atlantic Ridge may also reflect the significantly higher rates at which it is migrating compared to the southern Mid‐Atlantic Ridge.

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Segmentation and morphology of the Central Indian Ridge between 3°S and 11°S, Indian Ocean

Cited by 30 publications

References 49 publications

The Betic Ophiolites and the Mesozoic Evolution of the Western Tethys

The Betic Ophiolites and the Mesozoic Evolution of the Western Tethys

Geochemical, mineralogical, and Sr–Nd isotopic compositions of ferromanganese encrustations from Central Indian Ridge at 06°38.5′S

Distinctive Seafloor Fabric Produced Near Western Versus Eastern Ridge‐Transform Intersections of the Northern Mid‐Atlantic Ridge: Possible Influence of Ridge Migration

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