Isostatic response of the Laccadive Ridge from admittance analysis of gravity and bathymetry data

Chaubey, A.K.; Srinivas, K.; Ashalatha, B.; Rao, D. Gopala

doi:10.1016/j.jog.2008.03.001

Cited by 23 publications

(14 citation statements)

References 45 publications

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“…Earlier Te estimates of comparable passive margins, such as the flexural analyses of Chand and Subrahmanyam (2003), Sheena et al (2007Sheena et al ( , 2012, Tiwari et al (2007), and Chaubey et al (2008) were carried out in spectral domain along a 1D profile or using some discrete windows of variable size, but they could not produce the spatial variations necessary for the effective elastic thickness (Te), which we consider a serious shortcoming. In contrast to the earlier studies, the thin plate flexure model applied in the present study operates in the spatial domain (convolution method), which has such a significant advantage over the spectral methods that it overcomes the numerical instabilities in the admittance/coherence calculations.…”

Section: Advantages and Limitationsmentioning

confidence: 90%

“…Thus, there is a point of potential confusion regarding which parameter (rift or plume) played the predominant role in formulating the anomalously low elastic thickness along these passive margins. Chand and Subrahmanyam (2003) and Chaubey et al (2008) ruled out the prevalent role of plume, based on the moving rate of Indian plate. According to their idea, the Indian Plate keeps a fast moving rate of 13.5 cm/year over the Reunion hotspot between 66 and 48 Ma and that the thermal rejuvenation during this time may have been insufficient to change the plate strength.…”

Section: The Low-te Zones Along the Passive Margins-a Rift Related Simentioning

confidence: 99%

“…The traces of Reunion hotspot can be observed in both ECMM and WCMI (Tiwari et al, 2007;Chaubey et al, 2008). The major bathymetric features in the ocean to the east of Madagascar such as Nazareth Bank, Mauritius and Reunion Island, which are considered to be the remnants of the Reunion hotspot, exhibit anomalously thick crust and significant Te variations.…”

Section: The Low-te Zones Along the Passive Margins-a Rift Related Simentioning

confidence: 99%

“…5 for the hotspot track). Chaubey et al (2008) analyzed the isostatic compensation mechanism beneath the Laccadive Ridge using free air admittance, and they obtained a significantly low-Te value of~2.5 km. Their results favor a model of Airy isostatic compensation beneath the Laccadive ridge that resulted when stretched continental lithosphere was loaded during an initial stage of rifting.…”

Section: The Low-te Zones Along the Passive Margins-a Rift Related Simentioning

confidence: 99%

“…Sheena et al (2007) employed rectangular blocks for a coherence analysis along the Konkan and Kerala basins of the WCMI, which revealed a variation of lithospheric strength of 5 to 10 km. Chaubey et al (2008) derived Te using admittance (cross-spectral) analysis between 12 gravity and bathymetry profiles across the Laccadive Ridge, and obtained low-Te (2-3 km) values, which they attributed to the local compensation of stretched continental lithosphere. Ratheesh- Kumar et al (2014) derived spatial variations of the elastic thickness structure of the Indian Shield and adjoining regions using a fan wavelet-based Bouguer coherence technique.…”

Section: Introductionmentioning

confidence: 99%

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India–Madagascar paleo-fit based on flexural isostasy of their rifted margins

et al. 2015

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Section: Advantages and Limitationsmentioning

confidence: 90%

Section: The Low-te Zones Along the Passive Margins-a Rift Related Simentioning

confidence: 99%

Section: The Low-te Zones Along the Passive Margins-a Rift Related Simentioning

confidence: 99%

Section: The Low-te Zones Along the Passive Margins-a Rift Related Simentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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India–Madagascar paleo-fit based on flexural isostasy of their rifted margins

et al. 2015

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Seaward dipping reflectors along the SW continental margin of India: Evidence for volcanic passive margin

et al. 2010

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Multi-channel seismic reflection profiles across the southwest continental margin of India (SWCMI) show presence of westerly dipping seismic reflectors beneath sedimentary strata along the western flank of the Laccadive Ridge -northernmost part of the Chagos-Laccadive Ridge system. Velocity structure, seismic character, 2D gravity model and geographic locations of the dipping reflectors suggest that these reflectors are volcanic in origin, which are interpreted as Seaward Dipping Reflectors (SDRs).The SDRs; 15 to 27 km wide overlain by ∼ 1 km thick sediment; are observed at three locations and characterized by stack of laterally continuous, divergent and off-lapping reflectors. Occurrence of SDRs along western flank of the Laccadive Ridge adjacent to oceanic crust of the Arabian Basin and 2D crustal model deduced from free-air gravity anomaly suggest that they are genetically related to incipient volcanism during separation of Madagascar from India.We suggest that (i) SWCMI is a volcanic passive margin developed during India-Madagascar breakup in the Late Cretaceous, and (ii) continent-ocean transition lies at western margin of the Laccadive Ridge, west of feather edge of the SDRs. Occurrence of SDRs on western flank of the Laccadive Ridge and inferred zone of transition from continent to ocean further suggest continental nature of crust of the Laccadive Ridge.

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Gravity anomalies, crustal structure and rift tectonics at the Konkan and Kerala basins, western continental margin of India

et al. 2012

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Litho-stratigraphic variation of sedimentary units constructed from seismic sections and gravity anomaly in the Konkan and Kerala basins of the western continental margin of India (WCMI) have been used to model processes such as lithospheric rifting mechanism, its strength, and evolution of flank uplift topography that led to the present-day Western Ghats escarpment. Based on the process-oriented approach, two lithospheric models (necking and magmatic underplating) of evolution of the margin were tested. Both, necking and underplating models suggest an effective elastic thickness (Te) of 5 km and 10 km along Konkan and Kerala basins, respectively and a deep level of necking at 20 km at both basins. Model study suggests that the necking model better explains the observed gravity anomalies in the southern part of the WCMI. A synthesis of these results along with the previously published elastic thickness estimates along the WCMI suggests that a low-to-intermediate strength lithosphere and a deeper level of necking explains the observed flank-uplift topography of the Western Ghats. Process-oriented gravity modelling further suggests that the lateral variations in the lithospheric strength, though not very significant, exist from north to south within a distance of 600 km in the Konkan and Kerala basins along the WCMI at the time of rifting. A comparison with previous Te estimates from coherence analysis along the WCMI indicates that the lithospheric strength did not change appreciably since the time of rifting and it is low both onshore and offshore having a range of 5-15 km.

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Isostatic response of the Laccadive Ridge from admittance analysis of gravity and bathymetry data

Cited by 23 publications

References 45 publications

India–Madagascar paleo-fit based on flexural isostasy of their rifted margins

India–Madagascar paleo-fit based on flexural isostasy of their rifted margins

Seaward dipping reflectors along the SW continental margin of India: Evidence for volcanic passive margin

Gravity anomalies, crustal structure and rift tectonics at the Konkan and Kerala basins, western continental margin of India

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