Journal of Palaeosciences

Mesozoic Oceanic Anoxic Events: Records from India and future scope

2024-07-19T11:25:26+0530

This paper presents a review of the Mesozoic Oceanic Anoxic Event (OAE) studies, carried out from India. It also provides a summary of the researches pursued on biostratigraphic, isotopic, and organic geochemical proxies for establishing Oceanic Anoxic Events (OAEs) from the Mesozoic sedimentary sequences of the Indian Subcontinent. From Indian sedimentary basins, studies are available on OAE-1a, OAE-1b, OAE-1d, OAE-2, and OAE-3. From the Cauvery Basin records of OAE-1b, OAE-1d, OAE-2, and OAE-3 are available. From the Spiti Valley records are present on OAE-2 (Chikkim Formation) only, and the possibilities of late Valanginian Weissert Event (W-OAE), latest Hauterivian Faraoni Event (F-OAE) and OAE-1a are expected to be present in Giumal Formation. Nonetheless, the Black shale from Rudramata Shale, Jhuran Formation indicate possible late Jurassic OAE, based on the character of sedimentary facies and organic geochemical results. There is also, possibility of OAE-1a and OAE-1b in the Ukra and Upper member of the Bhuj Formation. This paper aims to provide a comprehensive introduction on global and regional OAEs records from the Indian subcontinent and a significant window on available knowledge of these events in India and supply significant attention for the future research possibilities from the Indian landmass.

Probable Record of Paleocene - Eocene Thermal Maximum in Southwestern Nigeria: Indications from Nannofossils of FA-1 Borehole, Eastern Benin Basin.

2024-05-27T11:08:17+0530

The Paleocene – Eocene Thermal Maximum (PETM) interval has been reported in several calcareous nannofossil studies from Paleogene basins around world including the Southern Tethys basins of North Africa. The Southern Tethys basins are believed to be connected to the Eastern Benin Basin through the Trans – Saharan Seaway during the Paleogene. Based on these reports, we carried out a biostratigraphic and paleoclimatic analyses of the calcareous nannofossils recovered from 25 ditch cutting samples in the FA-1 borehole to investigate possible record of the PETM in the Eastern Benin Basin, Southwestern Nigeria. The samples yielded characteristic Paleocene – Eocene calcareous nannofossils species (Coccolithus pelagicus, Coccolithus formosus, Chiasmolithus solitus, Sphenolithus moriformis, Pontosphaera plana, Pontosphaera multipora, Lophodolithus mochioporus, Lophodolithus nanscens, Neochiastozygus perfectus and Zeugrhabdotus sigmoides) and the Maastrichtian species, Arkhangeskiella cymbiformis. The assemblages allow the recognition of CC 22 (Maastrichtian) and NP 4 – NP 6 (early – late Paleocene) nannofossil zones. The relatively abundant occurrences of the genus Coccolithus and Sphenolithus in the carbonate interval of borehole suggest prevailing oligotrophic, warm water condition. The barren interval succeeding the peak nannofossil abundance at sample 159 m coincides with the onset of continuous clastic sedimentation in the FA-1 borehole. This is believed to have resulted from the shoaling of the Calcite Compensation Depth (CCD) and increased clastic input occasioned by the climatic and ocean water perturbations of the PETM interval. The emergence of the genus Pontosphaera (Pontosphaera plana and Pontosphaera multipora) at depth 87 m above the barren interval suggest a return to cooler, mesotrophic to eutrophic water condition after the drastic temperature rise and oligotrophic waters of the PETM.

Key-words - Calcareous nannofossils, Paleocene - Eocene, Benin Basin, Thermal Maximum.

A Preliminary Organic Geochemical and Petrographical Investigation of Neyveli lignite (mine-1) to Understand the Depositional Environment and Hydrocarbon Source Characteristics.

2024-08-16T17:08:30+0530

The lignite deposit of Neyveli mine-1 associated with the Cuddalore formation (Miocene) of Cauvery Basin, South India is studied using a combination of organic geochemical (FTIR spectroscopy and GC-MS) and organic petrographical analyses to identify the composition and kerogen type to reconstruct its palaeoflora and palaeodepositional setting. Also, its rank, thermal maturity, and hydrocarbon source potential are identified. The huminite macerals (78.11 av. vol.%) were found to be the most abundant. The petrographical facies indices (GI-TPI, GWI-VI), Paq values, and Pr/n-C₁₇vs. Ph/n-C₁₈ plot indicate a mixed type of organic matter deposited in a limno-telmatic regime under mesotrophic to rheotrophic hydrological conditions. The presence of herbaceous plants is supported by a high percentage of detrohuminite, VI values, and mid-chain alkanes. The presence of ulminite, resinite, sporinite, suberinite and cutinite, fluorescing huminite, high CPI (avg. 3.16) and TAR values (avg. 17.27), high P_wax ratio (avg. 0.81) and high abundance of longer chain alkanes (n-C₂₇ and n-C₂₉), supports the presence of higher plants. Short-chain alkanes and alginite support algal input. The percentage of funginite (3.18 avg. vol.%) and the ACL values represent a warm and humid palaeoclimate. The Pr/Ph ratio and Pr/n-C₁₇vs Ph/n-C₁₈ plot indicate the suboxic to anoxic redox conditions (transitional environment). Minimal peat fires and periodic flooding events contributed to the low rank. Hydroxyl (3656-3226 cm^-1), aliphatic stretching and bending (2847-2954 cm^-1, 1377-1451 cm^-1), aromatic (1513-1615 cm^-1) and carboxyl groups (1701-1709 cm^-1) are obtained from FTIR spectra. The huminite reflectance measurement gives a rank of low-rank B (av. 0.37% R_r), and OEP values indicate immaturity. The different ternary diagrams and pseudo-Van Krevelen diagram indicate this lignite possesses admixed type-III/II kerogen which can generate heavy hydrocarbons. By also considering the presence of pre-oil solid bitumen, the Neyveli mine-1 lignite is identified as gas-prone and capable of oil generation.

Habrotrocha angusticollis from Miocene sediments and their extant forms in the Indian sub-continent

2024-10-28T13:07:32+0530

Microscopic biotic remains in Upper Miocene clayey sediments of Sevok group (Siwaliks) present along the Sevok river, Oodhlabari area, Darjeeling district was studied. The sedimentary section constitutes grey marly-clay, nodular siltstone along with intermittent fine grained sandstone. The flask-shaped fossil shells were observed in clayey sediments which resembled the shells of their nearest living counterpart Habrotrocha angusticollis found as a rare rotifer in lakes of NEI. We also studied the modern H.angusticollis in high rainfall region of Western Ghats, Karnataka and found their shells in abundance along with testate amoebae, diatoms and desmids in moss cushions from Virajpet and Madikeri. The shells of extant forms in Western Ghats were of one type but the fossil shells from Upper Miocene in north-eastern part of India (NEI) were of about 7 types. These vary from round-bottom flask to pear shaped body suggesting more diversity in NEI in the past that survived in wetter conditions and moderate temperatures very similar to misty climate in rainforests of Western Ghats and NEI. We infer that shells of Habrotrocha angusticollis serve as indicators of terrestrial (palaeo) ecology and (palaeo) climate of highly moist (≥90% humidity) under-storey substrate in rainforest region.

Diverse geniculate coralline algae in Cenozoic fossil records: knowledge gaps and applications in palaeoecology

2024-10-09T17:37:39+0530

Coralline red algae (Corallinophycideae) are marine calcifying primary producers documented in euphotic habitats globally. Cenozoic carbonate sediments of India put forward an excellent opportunity for the analysis of coralline algae, their contribution in reconstruction of benthic palaeoenvironments and response to climate change. Compared to the common integrated analysis of non-geniculate coralline morphotypes with benthic groups like corals and larger benthic foraminifera, application of geniculate coralline algae is relatively very poor in palaeoecological studies. In order to understand their diversity and status in the Cenozoic fossil records, analysis of limestones and benthic assemblages from the Lakadong Limestone, Prang Formation (Meghalaya, NE India), Fulra Limestone Formation (Kutch Basin, W India), Long Formation (Little Andaman Island) and Guitar Formation (Car Nicobar Island) is carried out in addition to a concise review of existing literature. Critical gaps in our understanding of fossil geniculate coralline algae are discussed emphasizing on the usually overlooked methodological constraints.

Fossil Leaves Belonging to Family Annonaceae from Sub-Himalayan Zone (Siwalik) of Himachal Pradesh, India and their Climatic and Phytogeographical Implication

2024-10-17T17:47:21+0530

Investigation on the fossil leaves collected from Middle Siwalik sediments of Sarkaghat area, in the Sub-Himalayan zone of Himachal Pradesh revealed the presence of four new fossil species belonging to the family Annonaceae. The fossil leaves have been identified with the extant species, Annona reticulate Linn. Polyalthia longifolia (Son.) Thw. P. siamiarum (Buchanan-Hamilton ex Hooker and Thomson and cananga odorata Hook. f. and Th. The analysis of the current distribution of fossils' nearest living relatives (NRLs) shows that these species are currently found in the evergreen forests of northeastern and south-east Asia, rather than in and around the study area or throughout the sub-Himalayan zone of India. This suggests that after Miocene these taxa could not survive there and migrated towards south and south-east region. Based on the data available the phytogeographical aspect of these fossil taxa along with family Annonaceae has been discussed.

XV International Palynology Congress and XI International Organisation of Palaeobotany Conference

2024-12-26T13:09:27+0530

40th Convention of the Indian Association of Sedimentologists and National Conference on An Odyssey of Sedimentology from Precambrian to Anthropocene: Significant Contributions in Environmental, Climatic, and Energy Research

2024-12-24T16:28:06+0530