Pub Date : 2023-12-24DOI: 10.1177/05529360231219329
Divya Geddada, Kanchi Narsimha
A palynological study on subsurface Early Cretaceous sediments (1550–1860 m) in well JM-A located in Dhansiri Valley, Upper Assam Shelf has been carried out for determination of age and depositional environment. The palynological investigations resulted into the identification of the characteristic and diversified occurrence of Early Cretaceous dinoflagellate cysts comprising Batioladinium micropodum, Achomosphaera? neptuni, Batiacasphaera asperata, Lagenorhytis sp. cf. L. delicatula, Mendicodinium caperatum and Canningia sp. along with associated dinoflagellate cysts. The significant assemblage of spore-pollen assemblage represented by Cicatricosisporites australiensis, Ceratosporites equalis, Gleicheniidites circinidites, Contignisporites cooksonii, Microcachryidites antarcticus, Podosporites tripakshii and Callialasporites trilobatus has also been recorded. The Early Cretaceous sediments are regarded as Bamangaon Formation in Dhansiri Valley. The occurrence of dinoflagellate cysts suggests marginal marine environment for Bamangaon Formation deposited during the Early Cretaceous period corresponding to the Rift Phase. The Formation overlies the Metamorphic Basement Complex, and it is unconformably overlain by the sediments of Tura Formation of Ypresian (Early Eocene) age, deposited under subtidal to inner shelf environment during the Passive Margin Tectonic Phase.
{"title":"Record of Early Cretaceous dinoflagellate cysts from well JM-A, Dhansiri Valley of Upper Assam Shelf, India","authors":"Divya Geddada, Kanchi Narsimha","doi":"10.1177/05529360231219329","DOIUrl":"https://doi.org/10.1177/05529360231219329","url":null,"abstract":"A palynological study on subsurface Early Cretaceous sediments (1550–1860 m) in well JM-A located in Dhansiri Valley, Upper Assam Shelf has been carried out for determination of age and depositional environment. The palynological investigations resulted into the identification of the characteristic and diversified occurrence of Early Cretaceous dinoflagellate cysts comprising Batioladinium micropodum, Achomosphaera? neptuni, Batiacasphaera asperata, Lagenorhytis sp. cf. L. delicatula, Mendicodinium caperatum and Canningia sp. along with associated dinoflagellate cysts. The significant assemblage of spore-pollen assemblage represented by Cicatricosisporites australiensis, Ceratosporites equalis, Gleicheniidites circinidites, Contignisporites cooksonii, Microcachryidites antarcticus, Podosporites tripakshii and Callialasporites trilobatus has also been recorded. The Early Cretaceous sediments are regarded as Bamangaon Formation in Dhansiri Valley. The occurrence of dinoflagellate cysts suggests marginal marine environment for Bamangaon Formation deposited during the Early Cretaceous period corresponding to the Rift Phase. The Formation overlies the Metamorphic Basement Complex, and it is unconformably overlain by the sediments of Tura Formation of Ypresian (Early Eocene) age, deposited under subtidal to inner shelf environment during the Passive Margin Tectonic Phase.","PeriodicalId":48900,"journal":{"name":"Journal of the Palaeontological Society of India","volume":"1984 8","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139160608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-24DOI: 10.1177/05529360231220693
R. Panchang, Rajiv Nigam, Mugdha Ambokar
Pteropods are important components of the marine zooplankton. Not only are they crucial parts of the pelagic ecosystem but are also key contributors to the global carbon budget. Their shells sink to the ocean floor contributing to the inorganic carbon supply to the ocean floor. Being aragonitic, they easily dissolve in oceans receiving fresh water. They also dissolve as they sink beyond the Aragonite Saturation Zone, that is, within the top 500 m of the water column, releasing the trapped CO2 into the surrounding waters. Their taxonomic and quantitative distribution on the modern ocean floor can help strengthen estimates of inorganic carbon supply in shallow oceans, which are also susceptible to climate-induced dissolution. The present study, for the first time, reports 18 pteropod taxa, their abundances and spatial distribution from the surface sediments of the Ayeyarwady Delta Shelf in the North Andaman Sea, characterised by a very high influx of riverine water and sediments.
{"title":"Spatial distribution of pteropods from North Andaman Sea: Insights into aragonite supply and deposition in low saline, delta shelf regimes","authors":"R. Panchang, Rajiv Nigam, Mugdha Ambokar","doi":"10.1177/05529360231220693","DOIUrl":"https://doi.org/10.1177/05529360231220693","url":null,"abstract":"Pteropods are important components of the marine zooplankton. Not only are they crucial parts of the pelagic ecosystem but are also key contributors to the global carbon budget. Their shells sink to the ocean floor contributing to the inorganic carbon supply to the ocean floor. Being aragonitic, they easily dissolve in oceans receiving fresh water. They also dissolve as they sink beyond the Aragonite Saturation Zone, that is, within the top 500 m of the water column, releasing the trapped CO2 into the surrounding waters. Their taxonomic and quantitative distribution on the modern ocean floor can help strengthen estimates of inorganic carbon supply in shallow oceans, which are also susceptible to climate-induced dissolution. The present study, for the first time, reports 18 pteropod taxa, their abundances and spatial distribution from the surface sediments of the Ayeyarwady Delta Shelf in the North Andaman Sea, characterised by a very high influx of riverine water and sediments.","PeriodicalId":48900,"journal":{"name":"Journal of the Palaeontological Society of India","volume":"2008 13","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139160266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-24DOI: 10.1177/05529360231219324
K. Radhakrishnan, S.M. Hussain, P. Prakasheswar, Desna Mary Augustine, Vijayaraman
The present study is the first taxonomical account of Ostracoda occurring in the sediments of the Ashtamudi Lake in Kerala, intending to generate a baseline for future palaeo-ecological or palaeoenvironmental applications. A total of 22 Ostracod species belonging to 16 genera, 11 families, 5 superfamilies and 2 suborders of the order Podocopida have been identified from 66 surface sediment samples collected across the lake. Sedimentological parameters, such as CaCO3, organic matter, sand silt and clay, were estimated and their distribution is discussed. The ratio between the carapaces and open valves has been taken into consideration for determining the rate of sedimentation in the study area.
{"title":"A first report on the distribution of Ostracod taxa in the Ashtamudi Lake, southwest coast of Kerala, India","authors":"K. Radhakrishnan, S.M. Hussain, P. Prakasheswar, Desna Mary Augustine, Vijayaraman","doi":"10.1177/05529360231219324","DOIUrl":"https://doi.org/10.1177/05529360231219324","url":null,"abstract":"The present study is the first taxonomical account of Ostracoda occurring in the sediments of the Ashtamudi Lake in Kerala, intending to generate a baseline for future palaeo-ecological or palaeoenvironmental applications. A total of 22 Ostracod species belonging to 16 genera, 11 families, 5 superfamilies and 2 suborders of the order Podocopida have been identified from 66 surface sediment samples collected across the lake. Sedimentological parameters, such as CaCO3, organic matter, sand silt and clay, were estimated and their distribution is discussed. The ratio between the carapaces and open valves has been taken into consideration for determining the rate of sedimentation in the study area.","PeriodicalId":48900,"journal":{"name":"Journal of the Palaeontological Society of India","volume":"520 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139160771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-20DOI: 10.1177/05529360231205134
Rahul Sirvi, Aneesh Soman, V. D. Borkar, K. Kulkarni
A sandstone included in the Bagh Formation occurs at Belam Bujurg, District Khargone, Madhya Pradesh. Its stratigraphic position is controversial. Bose considered it as Nimar Sandstone. His observation, that it is capped by a limestone containing bryozoans, implies that Sitapuri Bryozoan Limestone directly overlies Nimar Sandstone at Belam Bujurg. However, it is contradictory to Chiplonkar’s (1982) observation that Nodular limestone is invariably associated with Nimar Sandstone. According to Roy Chowdhury and Sastri (1954, 1958), this sandstone is an intercalation within the Sitapuri Bryozoan Limestone. Later, Badve (1987) correlated this sandstone with Nimar Sandstone on the basis of similar ichnofauna and believed that overlying limestone cap represented calcareous facies coming at the top of Nimar Sandstone. However, elsewhere frequency and variety of trace fossils are distinctly more in limestone layers, in comparison to sandstone layers. Moreover, the presence of similar trace fossils indicates similarity in the conditions of deposition, rather than correlation. Recent fieldwork by the present authors corroborates that this sandstone is an intercalation within Sitapuri Bryozoan Limestone. Identification of the bryozoan Limestone was confirmed by petrographic study in thin section.
{"title":"Reappraisal of stratigraphic position of a sandstone included in the Bagh Formation, exposed near Belam Bujurg, Khargone District, Madhya Pradesh, India","authors":"Rahul Sirvi, Aneesh Soman, V. D. Borkar, K. Kulkarni","doi":"10.1177/05529360231205134","DOIUrl":"https://doi.org/10.1177/05529360231205134","url":null,"abstract":"A sandstone included in the Bagh Formation occurs at Belam Bujurg, District Khargone, Madhya Pradesh. Its stratigraphic position is controversial. Bose considered it as Nimar Sandstone. His observation, that it is capped by a limestone containing bryozoans, implies that Sitapuri Bryozoan Limestone directly overlies Nimar Sandstone at Belam Bujurg. However, it is contradictory to Chiplonkar’s (1982) observation that Nodular limestone is invariably associated with Nimar Sandstone. According to Roy Chowdhury and Sastri (1954, 1958), this sandstone is an intercalation within the Sitapuri Bryozoan Limestone. Later, Badve (1987) correlated this sandstone with Nimar Sandstone on the basis of similar ichnofauna and believed that overlying limestone cap represented calcareous facies coming at the top of Nimar Sandstone. However, elsewhere frequency and variety of trace fossils are distinctly more in limestone layers, in comparison to sandstone layers. Moreover, the presence of similar trace fossils indicates similarity in the conditions of deposition, rather than correlation. Recent fieldwork by the present authors corroborates that this sandstone is an intercalation within Sitapuri Bryozoan Limestone. Identification of the bryozoan Limestone was confirmed by petrographic study in thin section.","PeriodicalId":48900,"journal":{"name":"Journal of the Palaeontological Society of India","volume":"97 17","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138954108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-18DOI: 10.1177/05529360231219623
Mugdha Ambokar, R. Panchang, Pawan Govil, Syed Azharuddin
Pteropod aragonitic shells contribute to 12% of biogenic inorganic carbon flux to the world ocean but are also prone to dissolution. Though their state of preservation and generic ratios, namely Creseis/Limacina have been used as a proxy for palaeoclimatic reconstruction, their taxonomic attributes have remained unexplored. The present study reports 20 pteropod species from a single location in the northeastern Arabian Sea offshore of Saurashtra, all of which show the same degree of preservation throughout the core. The occurrence of mesopelagic fauna in the study area located on the shelf region however points to palaeoenvironmental changes and underscores the importance of employing pteropod assemblages for palaeoclimatic reconstructions in the study area.
{"title":"A first account of pteropod taxa from off Saurashtra, western offshore of India: Implications for palaeohydrological studies","authors":"Mugdha Ambokar, R. Panchang, Pawan Govil, Syed Azharuddin","doi":"10.1177/05529360231219623","DOIUrl":"https://doi.org/10.1177/05529360231219623","url":null,"abstract":"Pteropod aragonitic shells contribute to 12% of biogenic inorganic carbon flux to the world ocean but are also prone to dissolution. Though their state of preservation and generic ratios, namely Creseis/Limacina have been used as a proxy for palaeoclimatic reconstruction, their taxonomic attributes have remained unexplored. The present study reports 20 pteropod species from a single location in the northeastern Arabian Sea offshore of Saurashtra, all of which show the same degree of preservation throughout the core. The occurrence of mesopelagic fauna in the study area located on the shelf region however points to palaeoenvironmental changes and underscores the importance of employing pteropod assemblages for palaeoclimatic reconstructions in the study area.","PeriodicalId":48900,"journal":{"name":"Journal of the Palaeontological Society of India","volume":"113 ","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139173723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Detailed palynological investigations have been carried out to reconstruct stratigraphy and interpretation of depositional environment of Tura and Pre-Tura sedimentary sections in Dhansiri Valley of Upper Assam Shelf, Assam & Assam-Arakan Basin. Sediments of the Tura Formation dated as Early Eocene and interpreted to be deposited under subtidal to inner shelf environment. Pre-Tura sediments, developed in studied wells, led to the identification of Dergaon, Bamangaon and Moabund formations with intervening unconformities, having different tectonic history and distinct palynofossil assemblages. Early Permian sediments of the Dergaon Formation (=Talchir Formation), the oldest in the basin are deposited under the intracratonic phase, overlie the metamorphic basement complex. The sediments of the Dergaon Formation are unconformably overlain by the Bamangaon Formation deposited during the Early Cretaceous, whereas, in well DR-A, the sediments of the Dergaon Formation are directly overlain by the Moabund Formation corresponding to the Late Maastrichtian age. The sediments of the Tura Formation overlie the Maobund Formation in well DR-A, and they overlie the Bamangaon Formation in the rest of the wells in Dhansiri Valley.
{"title":"Palynostratigraphy and depositional environment of Tura and Pre-Tura sedimentary successions in Dhansiri Valley of Upper Assam Shelf, Assam & Assam-Arakan Basin, Assam, India","authors":"Kanchi Narsimha, Lusuchu Phor, Tushar Kanti Ghosh, Sudeshna Panda, Divya Geddada, Biswa Prakash Patra","doi":"10.1177/05529360231216337","DOIUrl":"https://doi.org/10.1177/05529360231216337","url":null,"abstract":"Detailed palynological investigations have been carried out to reconstruct stratigraphy and interpretation of depositional environment of Tura and Pre-Tura sedimentary sections in Dhansiri Valley of Upper Assam Shelf, Assam & Assam-Arakan Basin. Sediments of the Tura Formation dated as Early Eocene and interpreted to be deposited under subtidal to inner shelf environment. Pre-Tura sediments, developed in studied wells, led to the identification of Dergaon, Bamangaon and Moabund formations with intervening unconformities, having different tectonic history and distinct palynofossil assemblages. Early Permian sediments of the Dergaon Formation (=Talchir Formation), the oldest in the basin are deposited under the intracratonic phase, overlie the metamorphic basement complex. The sediments of the Dergaon Formation are unconformably overlain by the Bamangaon Formation deposited during the Early Cretaceous, whereas, in well DR-A, the sediments of the Dergaon Formation are directly overlain by the Moabund Formation corresponding to the Late Maastrichtian age. The sediments of the Tura Formation overlie the Maobund Formation in well DR-A, and they overlie the Bamangaon Formation in the rest of the wells in Dhansiri Valley.","PeriodicalId":48900,"journal":{"name":"Journal of the Palaeontological Society of India","volume":"12 11","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138584318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-14DOI: 10.1177/05529360231205315
Amruta R. Paranjape, Kantimati G. Kulkarni, Anand S. Kale
The Sillakudi Formation is a sandstone-dominated succession bounded by unconformities. It represents the oldest unit of the Ariyalur Group deposited during the Campanian under fully established passive margin depositional conditions. The present study is an attempt to interpret the depositional palaeoenvironment of Sillakudi Formation based on its trace fossil content, supported by sedimentological evidences. Detailed sedimentological and ichnological observations were undertaken in multiple traverses and spot locations across the Sillakudi Formation. The Sillakudi Formation is subdivided into four facies associations, each represented by a distinct ichnology and environment of deposition. Unit 1 comprises conglomerates grading upwards into pebbly sandstones almost devoid of trace fossils except a few Planolites isp. indicating a high-energy foreshore-to-shoreface environment. Unit 2 consists of glauconitic sandstones with Ophiomorpha nodosa, O. annulata, Thalassinoides isp. and Skolithos linearis, belonging to the Skolithos ichnofacies indicating deposition in shoreface to offshore transition environments. Unit 3 comprises pebbly to very coarse-grained massive sandstones, characterised by an almost monospecific Skolithos ichnofacies indicating rapid colonisation of beds in a delta-front associated debris flows and calcareous sandstones alternating with claystones containing a diverse Cruziana ichnofacies with an ichnoassemblage comprising of Trichichnus isp., Scolicia prisca var. laminites, S. ?prisca, S. vertebralis, Palaeophycus tubularis, Planolites beverleyensis, P. montanus, Taenidium isp., Thalassinoides suevicus, Ophiomorpha isp., Chondrites isp. and Phycodes isp., pointing towards deposition in calmer, possibly dysoxic outer shelf prodeltaic environments. Unit 4 has pebbly to gritty cross-bedded sandstones exhibiting the development of networks of Thalassinoides isp. and Ophiomorpha isp., indicating shallow sub-tidal to intertidal conditions of deposition. The overall succession is interpreted to show initial deepening followed by shallowing.
西拉库地组是一个以不整合面为界的砂岩为主的序列。它代表了坎帕期在完全确定的被动边缘沉积条件下沉积的阿里亚鲁尔群中最古老的单元。本研究试图根据西拉库底组的微量化石含量，结合沉积学证据，对其沉积古环境进行解释。详细的沉积学和技术观察是在横跨西拉库地组的多个穿越点和地点进行的。西拉库底组可划分为四个相组，每个相组都代表着不同的沉积技术和沉积环境。第1单元由砾岩组成，这些砾岩向上递变为含砾砂岩，除了一些Planolites isp外，几乎没有任何化石痕迹。表明这是一个高能的前滨-滨面环境。第2单元由海绿石砂岩组成，其中有Ophiomorpha nodosa, O. annulata, Thalassinoides isp。和斯科利索线相，属于斯科利索相，表明沉积在滨向海过渡环境中。第3单元包括卵石到颗粒非常粗的块状砂岩，其特征是几乎单一的斯科利索斯岩相，表明三角洲前缘伴生泥石流中床的快速定殖，钙质砂岩与粘土岩交替存在，包含多种克鲁齐亚纳岩相，其岩石组合包括Trichichnus isp。，斑纹棘虫，斑纹棘虫，脊椎棘虫，管状古棘虫，贝弗利扁石器，山棘虫，带绦虫。，海蛸，蛇胚目;，球粒陨石。和Phycodes isp。，指出沉积在较平静的，可能是缺氧的外陆架原生三角洲环境。第4单元有卵石和砂质交错层状砂岩，显示了Thalassinoides isp网络的发展。和蛇麻草。，表明浅层潮下至潮间带的沉积条件。整体演替被解释为先加深后变浅。
{"title":"Facies and trace fossils of the Upper Cretaceous Sillakudi Formation (Cauvery Basin, S. India) and their palaeoenvironmental significance","authors":"Amruta R. Paranjape, Kantimati G. Kulkarni, Anand S. Kale","doi":"10.1177/05529360231205315","DOIUrl":"https://doi.org/10.1177/05529360231205315","url":null,"abstract":"The Sillakudi Formation is a sandstone-dominated succession bounded by unconformities. It represents the oldest unit of the Ariyalur Group deposited during the Campanian under fully established passive margin depositional conditions. The present study is an attempt to interpret the depositional palaeoenvironment of Sillakudi Formation based on its trace fossil content, supported by sedimentological evidences. Detailed sedimentological and ichnological observations were undertaken in multiple traverses and spot locations across the Sillakudi Formation. The Sillakudi Formation is subdivided into four facies associations, each represented by a distinct ichnology and environment of deposition. Unit 1 comprises conglomerates grading upwards into pebbly sandstones almost devoid of trace fossils except a few Planolites isp. indicating a high-energy foreshore-to-shoreface environment. Unit 2 consists of glauconitic sandstones with Ophiomorpha nodosa, O. annulata, Thalassinoides isp. and Skolithos linearis, belonging to the Skolithos ichnofacies indicating deposition in shoreface to offshore transition environments. Unit 3 comprises pebbly to very coarse-grained massive sandstones, characterised by an almost monospecific Skolithos ichnofacies indicating rapid colonisation of beds in a delta-front associated debris flows and calcareous sandstones alternating with claystones containing a diverse Cruziana ichnofacies with an ichnoassemblage comprising of Trichichnus isp., Scolicia prisca var. laminites, S. ?prisca, S. vertebralis, Palaeophycus tubularis, Planolites beverleyensis, P. montanus, Taenidium isp., Thalassinoides suevicus, Ophiomorpha isp., Chondrites isp. and Phycodes isp., pointing towards deposition in calmer, possibly dysoxic outer shelf prodeltaic environments. Unit 4 has pebbly to gritty cross-bedded sandstones exhibiting the development of networks of Thalassinoides isp. and Ophiomorpha isp., indicating shallow sub-tidal to intertidal conditions of deposition. The overall succession is interpreted to show initial deepening followed by shallowing.","PeriodicalId":48900,"journal":{"name":"Journal of the Palaeontological Society of India","volume":"32 18","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134954274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-14DOI: 10.1177/05529360231209623
A. Rajeshkanna, R. Venkatachalapathy
The present study reports the occurrence of diatom taxa, their distribution and ecology in Thamirabarani River between the study areas Naranammalpuram and Punnakayal, covering the districts of Tirunelveli and Thoothukudiin Tamil Nadu, India. The study employs diatoms collected from 10 different locations in the Thamirabarani River to monitor its quality. A total of 40 diatom taxa belonging to 20 genera were recorded in the study area. The dominant presence of diatom taxa, such as Aulacoseira ambigua, Cocconeis placentula, Cyclotella meneghiniana, Cymbella tropica, Discostella stelligera, Gyrosigma acuminatum, Navicula cryptonella, Nitzschia amphibia, Planothidium lanceolatum, Staurosirella pinnata, and the water quality index values (29–48) recorded at sites 1 to 7 indicate oligotrophic due to good flow of water. The abundant of diatom taxa, such as Diadesmis confervacea, Gomphonema parvulum, Nitzschia palea and Pinnularia gibba, were recorded at sites 8–10, and the water quality indices (100–110) indicate eutrophication attributable to less flow of water, high dispersion of cremation ashes (the casting ceremony) and anthropogenic activities. Particularly, locations around Punnakayal are most polluted due to the dumping of fish wastes as well as stagnant water.
{"title":"Diatoms and Water Quality Indices in Thamirabarani River help Environmental Impact Assessment of stretch between Naranammalpuram and Punnakayal, Tamil Nadu, India","authors":"A. Rajeshkanna, R. Venkatachalapathy","doi":"10.1177/05529360231209623","DOIUrl":"https://doi.org/10.1177/05529360231209623","url":null,"abstract":"The present study reports the occurrence of diatom taxa, their distribution and ecology in Thamirabarani River between the study areas Naranammalpuram and Punnakayal, covering the districts of Tirunelveli and Thoothukudiin Tamil Nadu, India. The study employs diatoms collected from 10 different locations in the Thamirabarani River to monitor its quality. A total of 40 diatom taxa belonging to 20 genera were recorded in the study area. The dominant presence of diatom taxa, such as Aulacoseira ambigua, Cocconeis placentula, Cyclotella meneghiniana, Cymbella tropica, Discostella stelligera, Gyrosigma acuminatum, Navicula cryptonella, Nitzschia amphibia, Planothidium lanceolatum, Staurosirella pinnata, and the water quality index values (29–48) recorded at sites 1 to 7 indicate oligotrophic due to good flow of water. The abundant of diatom taxa, such as Diadesmis confervacea, Gomphonema parvulum, Nitzschia palea and Pinnularia gibba, were recorded at sites 8–10, and the water quality indices (100–110) indicate eutrophication attributable to less flow of water, high dispersion of cremation ashes (the casting ceremony) and anthropogenic activities. Particularly, locations around Punnakayal are most polluted due to the dumping of fish wastes as well as stagnant water.","PeriodicalId":48900,"journal":{"name":"Journal of the Palaeontological Society of India","volume":"52 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134901875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-09DOI: 10.1177/05529360231208812
Shweta Patil, Ashwin Pundalik, Eshan Pansare
The Kachchh basin is located on the northwestern margin of India. The basin consists of a relatively continuous sequence of sediments from the Mesozoic, followed by the Deccan Traps and finally a complete sequence of the Cenozoic sediments. The Cenozoic sediments of Kachchh basin are mainly shallow marine deposits characterised by five formations viz. Matanomadh, Naredi, Harudi, Fulra Limestone and Maniyara Fort Formation. The Maniyara Fort Formation belongs to the Oligocene age. The field and petrographic characteristics of the Oligocene limestones from the Golay river section were studied in order to understand the depositional environment. The petrographic investigation of the carbonate rocks of three members of the Maniyara Fort Formation, namely Lumpy Clay Member, Coral Limestone Member and Bermoti Member provides important information for understanding the depositional facies and diagenetic signatures. The Lumpy Clay Member has shale-siltstones with interbedded limestones, characteristically composed of a significant proportion of detrital grains of quartz and some lithic fragments. The lithic fragments are sub-angular to rounded, which indicates substantial transport. They are also worn down and broken, bear small cracks which are filled by micritic matrix or mud. The presence of stylolitic seams within the limestone (though not significant) along with mud filling is also noticed. The dissolution is not prominent, pointing towards shallow burial of the sediments. Paucity of marine fossils as well as the rarity of foraminifera in the Lumpy Clay Member indicate a restricted to semi-restricted shallow marine environment. The limestones of the Coral Limestone Member are petrographically classified as packstone, wackestone and mudstone. Thus, the environment of deposition seems to have varied from restricted lagoonal to shallow marine environment. The Bermoti Member is characterised by a lens of claystone, which consists of both greyish to yellow coloured claystones interbedded with limestones. The Bermoti limestones are petrographically classified as packstone, wackestone and mudstone assemblage. The limestones were observed to be highly micritised, which indicates open, shallow marine settings. The Maniyara Fort Formation, thus characterised by wackestone-packstone-mudstone facies of carbonates, is interpreted to be part of a carbonate ramp system. The limestones from Maniyara Fort Formation exhibit signatures of marine as well as meteoric diagenesis.
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Pub Date : 2023-11-05DOI: 10.1177/05529360231205313
Kapesa Lokho, JosÉ Francisco Carrasco, Shantajhara Biswal, Kezhakielie Whiso, Ansuya Bhandari
This article reports two echinoid taxa viz. Ilarionia sindensis Duncan and Sladen (1884) and Porocidaris schmidelii Münster in Goldfus (1830) from the middle Eocene Sylhet Limestone of Mikir Hills, Assam. P. schmidelii is found from the Lutetian (middle Eocene) to the Priabonian (upper Eocene) in the following regions: NE of Spain, Biarritz (Southwestern France), Angoumé (Southern Aquitaine, France), Carinthia (Southern Austria), Venetian region of Italy Provence, Southern Alps of French, Istria (Croatia), Persian Gulf, Oman and Egypt. I. sindensis was first reported from the Eocene of Sindh province from the Khirthar Series (Pakistan) and Madagascar. It is also recorded from the Bartonian–Priabonian in the following regions: NE Spain, Biarritz in Southwestern France, Angoumé in Southern Aquitaine-France, Carinthia in Southern Austria, Italian region of Veneto, Provence and southern French Alps, Persian Gulf, Oman, Egypt and Istria. They are systematically described to know their stratigraphic, palaeoenvironment and palaeogeographic distribution. The material studied herein represents the first report from the middle Eocene of India, and it significantly expands the geographical extension of Eocene marine echinoids in the northeastern part of India.
本文报道了阿萨姆邦Mikir山中始新世Sylhet石灰岩的两个棘类分类群Ilarionia sindensis Duncan and Sladen(1884)和Porocidaris schmidelii m nster in Goldfus(1830)。P. schmidelii在Lutetian(中始新世)至Priabonian(上始新世)发现于以下地区:西班牙东北部、比亚里茨(法国西南部)、angoum(法国南部阿基坦)、Carinthia(奥地利南部)、意大利普罗旺斯的威尼斯地区、法国南阿尔卑斯山、伊斯特里亚(克罗地亚)、波斯湾、阿曼和埃及。I. sindensis首次报道于信德省始新世，分布于Khirthar系列(巴基斯坦)和马达加斯加。在以下地区也有巴尔顿-普里亚伯尼亚时期的记录:西班牙东北部、法国西南部的比亚里茨、南阿基坦-法国的安古梅尔、奥地利南部的克恩顿州、意大利的威尼托地区、普罗旺斯和法国南部的阿尔卑斯山、波斯湾、阿曼、埃及和伊斯特拉。系统地描述了它们的地层、古环境和古地理分布。本文研究的材料是印度始新世中期的第一份报告，它极大地扩展了始新世海相棘虫在印度东北部的地理延伸。
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