A combined biostratigraphic study of dinoflagellate cysts and foraminifera was carried out on Early Cretaceous subsurface well cutting sediments from well A(DNG)(2800–2746 m depth)from the Krishna-Godavari Basin,Indi...A combined biostratigraphic study of dinoflagellate cysts and foraminifera was carried out on Early Cretaceous subsurface well cutting sediments from well A(DNG)(2800–2746 m depth)from the Krishna-Godavari Basin,India.The last appearance datum of marker species of dinoflagellate cysts and planktonic foraminifera was considered for the construction of the biostratigraphic framework.The study shows dominance of Early Cretaceous marker dinoflagellate cysts Cassiculosphaeridia magna,Cribroperidinium perforans,Hystrichodinium voigtii,Kleithriasphaeridium eoinodes,and planktonic foraminifera Hedbergella aptiana,Hedbergella mitra,Hedbergella praelippa,Hedbergella tardita,Microhedbergella miniglobularis and Hedbergella mitra species.In addition to this,the dinoflagellate cyst data were compared with the dinoflagellate biozones of Austral and Tethyan provinces.Based on earlier micropalaeontological records from the Krishna-Godavari Basin and the present study,a latest Barremian-early Aptian age has been determined for the earliest marine transgression in the Krishna-Godavari Basin.The early marine incursion during late Barremian-earliest Aptian in the Krishna-Godavari Basin compared to Albian age in Cauvery Basin suggests the opening of east coast from north to south.展开更多
The long-term seepage of hydrocarbons, either as macroseepage or microseepage, can set up near-surface oxidation reduction zones that favor the development of a diverse array of chemical and mineralogical changes. The...The long-term seepage of hydrocarbons, either as macroseepage or microseepage, can set up near-surface oxidation reduction zones that favor the development of a diverse array of chemical and mineralogical changes. The bacterial oxidation of light hydrocarbons can directly or indirectly bring about significant changes in the values of pH and Eh of the surrounding environment, thereby also changing the stability fields of the different mineral species present in that environment. The paper reports the role of hydrocarbon microseepage in surface alterations of trace metal concentrations. In this study trace metal alterations were mapped that appear to be associated with hydrocarbon microseepages in the oil/ gas fields. A total of 50 soil samples were collected near oil and gas fields of the Tatipaka and Pasarlapudi areas of the Krishna Godavari Basin, Andhra Pradesh. The soil samples were collected from a depth of 2-2.5 m. The paper reports the chemical alterations associated with trace metals in soils that are related to hydrocarbon microseepages above some of the major oil and gas fields of this petroliferous region. Trace metals, such as scandium (Sc), vanadium (V), chromium (Cr), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), barium (Ba) and strontium (Sr), in soil samples were analyzed using inductively coupled plasma- mass spectrometry (ICP-MS). The concentrations of Sc (8 to 40 mg/kg), V (197 to 489 mg/kg), Cr (106 to 287 mg/kg), Co (31 to 52 mg/kg), Ni (65 to 110 mg/kg), Cu (88 to 131 mg/kg), Zn (88 to 471 mg/kg), Ba (263 to 3,091 mg/kg) and Sr (119 to 218 mg/kg) were obtained. It was observed that the concentrations of trace elements were tremendously increased when they were compared with their normal concentrations in soils. The analysis of adsorbed soil gas showed the presence of high concentrations of YC2+ (C2H6, C3H8 and n-C4H10) ranging from 7 to 222 μg/kg respectively. Integrated studies of trace elements over adsor展开更多
基金funded By Ministry of Earth Science,Govt.of India under the sponsored project no.Mo ES Geo.Sci.(Po/36/2014).
文摘A combined biostratigraphic study of dinoflagellate cysts and foraminifera was carried out on Early Cretaceous subsurface well cutting sediments from well A(DNG)(2800–2746 m depth)from the Krishna-Godavari Basin,India.The last appearance datum of marker species of dinoflagellate cysts and planktonic foraminifera was considered for the construction of the biostratigraphic framework.The study shows dominance of Early Cretaceous marker dinoflagellate cysts Cassiculosphaeridia magna,Cribroperidinium perforans,Hystrichodinium voigtii,Kleithriasphaeridium eoinodes,and planktonic foraminifera Hedbergella aptiana,Hedbergella mitra,Hedbergella praelippa,Hedbergella tardita,Microhedbergella miniglobularis and Hedbergella mitra species.In addition to this,the dinoflagellate cyst data were compared with the dinoflagellate biozones of Austral and Tethyan provinces.Based on earlier micropalaeontological records from the Krishna-Godavari Basin and the present study,a latest Barremian-early Aptian age has been determined for the earliest marine transgression in the Krishna-Godavari Basin.The early marine incursion during late Barremian-earliest Aptian in the Krishna-Godavari Basin compared to Albian age in Cauvery Basin suggests the opening of east coast from north to south.
文摘The long-term seepage of hydrocarbons, either as macroseepage or microseepage, can set up near-surface oxidation reduction zones that favor the development of a diverse array of chemical and mineralogical changes. The bacterial oxidation of light hydrocarbons can directly or indirectly bring about significant changes in the values of pH and Eh of the surrounding environment, thereby also changing the stability fields of the different mineral species present in that environment. The paper reports the role of hydrocarbon microseepage in surface alterations of trace metal concentrations. In this study trace metal alterations were mapped that appear to be associated with hydrocarbon microseepages in the oil/ gas fields. A total of 50 soil samples were collected near oil and gas fields of the Tatipaka and Pasarlapudi areas of the Krishna Godavari Basin, Andhra Pradesh. The soil samples were collected from a depth of 2-2.5 m. The paper reports the chemical alterations associated with trace metals in soils that are related to hydrocarbon microseepages above some of the major oil and gas fields of this petroliferous region. Trace metals, such as scandium (Sc), vanadium (V), chromium (Cr), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), barium (Ba) and strontium (Sr), in soil samples were analyzed using inductively coupled plasma- mass spectrometry (ICP-MS). The concentrations of Sc (8 to 40 mg/kg), V (197 to 489 mg/kg), Cr (106 to 287 mg/kg), Co (31 to 52 mg/kg), Ni (65 to 110 mg/kg), Cu (88 to 131 mg/kg), Zn (88 to 471 mg/kg), Ba (263 to 3,091 mg/kg) and Sr (119 to 218 mg/kg) were obtained. It was observed that the concentrations of trace elements were tremendously increased when they were compared with their normal concentrations in soils. The analysis of adsorbed soil gas showed the presence of high concentrations of YC2+ (C2H6, C3H8 and n-C4H10) ranging from 7 to 222 μg/kg respectively. Integrated studies of trace elements over adsor