Mineral magnetic characteristics of the late Quaternary coastal red sands of Bheemuni, East Coast (India)

Srivastava, Poonam; Sangode, S. J.; Parmar, Nikita; Meshram, D. C.; Jadhav, Priyanka; Singhvi, A. K.

doi:10.1016/j.jappgeo.2016.08.005

Cited by 4 publications

(2 citation statements)

References 47 publications

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“…The weathering of volcanic rocks in a sub-aerial oxidizing environment alters coarser ferrimagnetic titano-(magnetite) particles into smaller fine superparamagnetic (SP)-SD ferrimagnetic particles and produces secondary iron oxides such as maghemite and hematite through oxidation and structural inversion 21 , 41 . The fine pigmentary hematite particles are often attributed to the red color of the soils and sediments, and can also form through chemical precipitation via hydrolysis during sub-aerial chemical weathering 41 , 42 . The magnetic analysis on clay separates indicates that the hematite is mainly associated with finer fractions in the WRGR red clay, and might have formed from the chemical precipitation during the chemical weathering of the WRGR volcanic rocks.…”

Section: Discussionmentioning

confidence: 99%

Red clays indicate sub-aerial exposure of the Rio Grande Rise during the Eocene volcanic episode

Srivastava,

J. Murton,

Sant’Anna

et al. 2023

Sci Rep

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Autonomous underwater vehicle (AUV) mapping of the western Rio Grande Rise (RGR), South Atlantic, and subsequent exploration and photography of horizontal lava flows exposed in near vertical, faulted escarpments, showed occurrences of red clays/weathered volcanic tops trapped between successive alkaline lava flows. These red clays indicate a hiatus in successive volcanic eruptions. Here, we report detailed mineralogical, geochemical, and rock magnetic characteristics of one such distinct red clay dredged from ~ 650 m water depth in the western RGR. The mineral constituents of the red clay are kaolinite, magnetite, oxidized magnetite (/maghemite), hematite, and goethite, with biogenic calcite and halite occupying voids or precipitated on the surface of the red clay. The chemical index of alteration (CIA) has a value of 93, showing that red clay is a product of extreme chemical weathering of the lava flows. The alkaline volcanic rocks recovered from nearby show an age of ~ 44 Ma, indicating an Eocene age for the volcanism. We show that the red clays are a product of sub-aerial chemical weathering of these Eocene volcanic rocks, in a warm-wet climate, before the thermal subsidence of the RGR to its modern-day bathymetric depth.

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Section: Discussionmentioning

confidence: 99%

Red clays indicate sub-aerial exposure of the Rio Grande Rise during the Eocene volcanic episode

Srivastava,

J. Murton,

Sant’Anna

et al. 2023

Sci Rep

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“…They also appear to have originated from fluvial and coastal dunes and are located about +12 m from the present sea level, indicating the strength of the aeolian processes (Gardner, 1995;Rao et al, 2006). Chronological data from the Indian red dunes suggests that they could have been deposited post LGM (Rao et al, 2006;Srivastava et al, 2016).…”

Section: Pleistocene Coastal Remarks and Evolutionmentioning

confidence: 99%

Coastal evolution and sediment succession of Sri Lanka: a review on quaternary sea levels, climates and sedimentation processes

Adikaram

Pitawala

Jayawardana

2018

J. Geol. Soc. Sri Lanka

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In spite of the small size, the coastal environments of the four cardinal quadrants of Sri Lanka indicate different morphologies and evolutionary characteristics. Therefore, a review of the coastal evolution and sediment succession of Sri Lanka is presented with formal published data and multi-proxy data using modern techniques. The Sri Lankan coasts have provided insightful evidence of paleo-sea level oscillations during the last glacial period and Late-Holocene epoch. The prevailing climate since the last glacial maximum has provided excessive sediment to coastal lowlands and produced Pleistocene sedimentary signatures driven with aeolian and fluvial processes. Major coastal sediment barriers developed during late Holocene transgressions and were modified afterwards. Both northwestern (NW) and southeastern (SE) coastal zones experienced the monsoon rain-shadow effect. In the NW quadrant, the shielding effect of the Indian sub-continent preserved much of the evidence for paleo-sea level oscillations and paleo-climate, although the basement rock is Miocene limestone. In contrast, the rocky crystalline SE coast has less preservation due to its considerable exposure to the wind driven forces. The energy of the of eastward moving currents is higher due to the combined effect of westerly wind bursts (WWB) and SW monsoons, and hence, southwestern (SW) and southern coastal areas show regressive coasts due to current generated coastal processes. However, the eastern zone of the SE quadrant is progressive due to its position in the conjunction zone of the eastward moving sea currents and westward moving lowsalinity water flows of the Bay of Bengal. The pattern of sea currents and monsoon strength controlled the wind driven morphologies of the NE and SW quadrants. Though the geology is similar in the NE and SW quadrants, the general geological strike of the SW coast is parallel to the turning SW monsoon currents and most likely the rock types has supported erosion. Sediment loads generated from NE monsoon and east India coastal currents (EICC) are upwelled with the strong circulations within the Bay of Bengal and deposit on the NE coasts indicating heavy mineral beds that were sorted by swash and backwash activities. This review notes how tropical monsoon induced sea currents and other currents around the Bay of Bengal region are factors in the differences in the geology and structure of coastal morphologies in four quadrants of Sri Lanka. These factors traced/erased the global melting events on a tropical small island during the Quaternary.

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Mineral magnetic properties of ultisol profiles from tropical southern India

Reethu,

Sandeep,

Sebastian

et al. 2023

Geosci J

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Mineral magnetic characteristics of the late Quaternary coastal red sands of Bheemuni, East Coast (India)

Cited by 4 publications

References 47 publications

Red clays indicate sub-aerial exposure of the Rio Grande Rise during the Eocene volcanic episode

Red clays indicate sub-aerial exposure of the Rio Grande Rise during the Eocene volcanic episode

Coastal evolution and sediment succession of Sri Lanka: a review on quaternary sea levels, climates and sedimentation processes

Mineral magnetic properties of ultisol profiles from tropical southern India

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