Temporal Trends of Geochemistry, Relative Sea Level, and Source Area Weathering in the Cauvery Basin, South India

Ramkumar, Mu.; Berner, Zsolt

doi:10.1016/b978-0-12-419968-2.00011-x

Cited by 5 publications

(19 citation statements)

References 111 publications

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“…Higher concentration of metals in hydrothermal sediments is attributed to their chelation to electron rich substrates (Calvert et al, ). The ability of organic ligands e.g., HA with which U(IV) can form insoluble organometallic complexes (Ramkumar & Berner, ) in the humic rich HT sediments may also be playing a role, thereby providing an additional mechanism for the persistence of high concentrations of U(IV) in the HT sediments as noted above (section 4.4.5).…”

Section: Discussionmentioning

confidence: 99%

“…The higher U/Th implied a reducing condition and authigenic deposition of the reduced, insoluble U(IV) (Jones & Manning, ; Ramkumar & Berner, ). The U/Fe ratio attests this inference (Mills et al, ) as the brown sediments had anomalously higher ratio (4.45 × 10 −5 in HT‐1 (57.5 cm bsf) and 8.09 × 10 −5 in HT‐2 (69.5 cm bsf) than the nonbrown sediments (2.19 ± 0.49 × 10 −5 ) imply a reducing condition and the authigenic deposition of the reduced, insoluble U(IV).…”

Section: Discussionmentioning

confidence: 99%

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Hydrothermal Alteration Promotes Humic Acid Formation in Sediments: A Case Study of the Central Indian Ocean Basin

et al. 2018

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Anomalously high concentrations of humic‐rich dissolved organic matter (DOM) in extant submarine hydrothermal vent plumes traveled far from source are increasingly being reported. This DOM, able to mobilize trace metals (e.g., Fe2+) has been hypothesized as originating from organic matter produced by thermogenic bacteria. To eliminate a possible abiogenic origin of this DOM, study is required of well‐preserved organic compounds that can be attributed to thermogenic bacteria. The Central Indian Ocean Basin (CIOB) is part of a diffuse plate boundary and an intraplate deformation zone. Coarse fraction (>63 µ) characteristics, mineralogy, magnetic susceptibility, and geochemistry were examined in sediments of a core raised close to a north‐south fracture zone near the Equator. Two horizons of distinctly brown‐colored sediments were shown as hydrothermally altered from their charred fragments and geochemistry (CaCO3, Corg, Ti/Al, Al/(Al + Fe + Mn), Sr/Ba, Mg/Li, Mn micronodules, Fe/Mn). We examined whether humic substances were preserved in these sediments, and if so whether their carbon isotope distribution would support their hydrothermal origin. Alkali extraction of sediments afforded humic acids (HA) in yields up to 1.2% in the brown sediments. The remaining portions of the core had nil or low concentrations of HA. The carbon of hydrothermal HA is isotopically heavier (average δ13C, ∼ −16.3‰) compared to nonhydrothermal HA (–18.1‰), suggesting that they were probably formed from organic matter that remained after elimination of lighter carbon enriched functional groups during diagenesis. The results provide compelling evidence of HA formation from lipids originating from thermogenic bacteria.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Hydrothermal Alteration Promotes Humic Acid Formation in Sediments: A Case Study of the Central Indian Ocean Basin

et al. 2018

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“…As each sedimentary environment is characterized by a unique set of the physical, chemical, and biological milieu in a geomorphic setup (Reineck & Singh, 1980) (Ayyasamy, 1990;Ramkumar, 2015;Ramkumar & Berner, 2015).…”

Section: Transience Of Weathering Sediment Influx Tectonics and Depos...mentioning

confidence: 99%

Major, trace and rare earth elemental geochemistry of Santonian–Campanian onland‐offshore transition in a Gilbert‐type deltaic setting, Cauvery Basin, southern India

et al. 2022

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The spatially widely distributed and temporally protracted Santonian-Campanian stratigraphic records of the Sillakkudi Formation of the Ariyalur Group, Cauvery Basin, southern India represent an onland exposure of a Gilbert-type delta. Here, we present geochemical, mineralogical, and petrographic analyses of two composite stratigraphic sections, and evaluate the climatic, tectonic, and other factors that contributed to the spatio-emporal uniqueness of this formation. A range of low to intensive weathering, simultaneous exhumation/erosion, physical transport, and chemical weathering, prevalent at different parts of the source region and or the existence of multiple channels that drained varied source regions and hence varied lithologies at exhumation surfaces which in turn experienced seasonally varied flow conditions were interpreted. The prevalence of physical erosion during the initial stages of the deposition of the Sillakkudi Formation that progressed towards higher intensities of chemical weathering, in tune with the increase in atmospheric temperature and sealevel rise during the later stages of the formation, is evidenced. Occurrences of positive and negative Eu anomalies and a progression from active to passive tectonic setting of samples, concomitant with change from tectonic control to relative sea-level and the sediment influx controlled nature of deposition from Santonian-Campanian is recorded. Together, three sets of related factors namely, tectonics, increase of atmospheric temperature and sea-level rise operated independently, and the enforced transience of transformation of the source terrain from active to passive margin, the transformation of depositional setting from fluvial to estuarine/intertidal to open marine, and shifting of principal loci of deposition from onland to offshore, are documented. The causal link between the progressive increase of sea-level control over the depositional system during the Santonian-Campanian as recorded by this study could be due to the rise in atmospheric temperature that in turn might have been influenced by the movement of the Indian Plate from low latitudes towards the equatorial region. The second implication of the results is that the studies attempting to document tectonic setting, provenance, and weathering, with the help of geochemical discriminant diagrams, should also consider the spatial and temporal changes in the source area as well as depositional setting.

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“…Notwithstanding considerable discussions on the climatic and environmental conditions, consensus on the timing, nature, rapidity, and relative contributions of causative mechanisms/events that led to extinction or dwindling of a number of species and population of organisms, as big and diverse as fishes and dinosaurs, to as small as marine plankton (Sugantha, Ramkumar, Balaram, Rai, & Satyanarayana, 2015) is yet to be evolved. Recent reviews (for example, Rai, Ramkumar, & Sugantha, 2013; Ramkumar, 2015a; Ramkumar & Berner, 2015; Ramkumar, Stüben, Berner, & Schneider, 2010; Ramkumar, Sugantha, & Rai, 2013; Sugantha et al, 2015) summarized that, although a variety of hypotheses are advocated for the end‐Cretaceous mass extinctions, they can be categorized into two, namely, (a) a sudden and catastrophic extinction event associated with a terminal Cretaceous bolide impact, and (b) gradual/stepwise extinction due to the environmental stress that resulted from a complex feedback of volcanism, and sea‐level changes (Keller & Abramovich, 2009) that spanned from a few thousand years to a few million years, prior to the Cretaceous–Palaeogene (K/Pg) boundary.…”

Section: Introductionmentioning

confidence: 99%

“…Interactions between these controlling factors, their variability, cyclicity, and perturbations create hierarchically‐recognizable facies associations. Among the marine sedimentary systems, the global sea‐level changes, either eustatic or any other cause, either long‐term, short‐term or perturbation, result in corresponding changes in biotic systems directly, by creating or depriving, expanding, and contracting the habitats (Ramkumar & Menier, 2017; Ramkumar, Menier, Manoj, & Santosh, 2016) available in oceans as well as on land, and/or indirectly through atmospheric, lithospheric, and oceanographic processes through their coupled nature (Ramkumar et al, 2016; Ramkumar & Berner, 2015; Ramkumar & Menier, 2017). The occurrence, proliferation, and dwindling of biota are essentially controlled by the environmental parameters (Chen, Joachimski, Montañez, & Isabell, 2014) of the ecological niches, which, in turn, exert variable controls over biota of varying lifestyles and ecological preferences (Fioroni, Villa, Persico, & Jovane, 2015; Ramkumar & Menier, 2017).…”

Section: Introductionmentioning

confidence: 99%

Opportunistic colonizers in the Kallankurichchi Formation, Cauvery Basin, South India: Implications on Maastrichtian environmental stress

Ramkumar

Siddiqui

Rai³

et al. 2020

Geological Journal

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Serpulids are marine filter-feeding annelids that live in calcareous tubes. Their distribution, colonization, and proliferation are dependent on physical environmental variables, including energy conditions. This article documents the occurrences of serpulid colonies over opportunistic colonizing trace fossil of Ophiomorpha-rich sedimentary unit in the Lower Maastrichtian Kallankurichchi Formation of the Ariyalur Group, Cauvery Basin, South India and links them with ecosystem dynamics, as a function of changes in eustatic and other relative sea-level changes and attendant variations in environmental parameters. Present observations indicate episodic changes in faunal composition, diversity, and population, across the boundary between Kattupiringiyam Inoceramus limestone Member and Tancem biostromal Member of the Kallankurichchi Formation. The boundary marked a significant change from lowmoderate energy, to high-energy waters, thus replacing a filter-feeding community by an opportunistic community. The opportunistic colonizers/trace makers of Ophiomorpha irregulaire occupied the ecospaces vacated by the sea-level changes.Systematic studies of faunal association across the boundary indicate a sudden appearance of significant populations of Serpula colonies above the surface (i.e., after the changes in ecosystem conditions) and enhancement of intensity of sponge boring in benthic organisms. This means that the changes brought about by the newer environmental conditions were supportive for opportunistic colonizers followed by parasitic and commensalic organisms. Significant reduction of Gryphaea population that was increasingly replaced by Alectryonia, Exogyra, and Terebratula is also documented. These changes, collectively, indicate prevalent environmental stress due to relative sea-level variations and attendant ecological conditions, to which, the opportunistic colonizers and parasitic organisms responded positively, while the native organisms dwindled in population and were forced to parasitic invasions.

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Temporal Trends of Geochemistry, Relative Sea Level, and Source Area Weathering in the Cauvery Basin, South India

Cited by 5 publications

References 111 publications

Hydrothermal Alteration Promotes Humic Acid Formation in Sediments: A Case Study of the Central Indian Ocean Basin

Hydrothermal Alteration Promotes Humic Acid Formation in Sediments: A Case Study of the Central Indian Ocean Basin

Major, trace and rare earth elemental geochemistry of Santonian–Campanian onland‐offshore transition in a Gilbert‐type deltaic setting, Cauvery Basin, southern India

Opportunistic colonizers in the Kallankurichchi Formation, Cauvery Basin, South India: Implications on Maastrichtian environmental stress

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