%0 Journal Article %1 WOS:000656957400001 %A de Souza, Ana Clara B %A do Nascimento Jr, Daniel R %A Filho, Francisco Nepomuceno %A Batezelli, Alessandro %A dos Santos, Felipe H %A Oliveira, Karen Leopoldino M %A de Almeida, Narelle Maia %C THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND %D 2021 %I ELSEVIER SCI LTD %J MARINE AND PETROLEUM GEOLOGY %K Cretaceous Geochemical Relative Transgressive-regressive anoxic events} hydrocarbon markers; potential; sequence; sequences; {Stratigraphic %R 10.1016/j.marpetgeo.2021.105074 %T Sequence stratigraphy and organic geochemistry: An integrated approach to understand the anoxic events and paleoenvironmental evolution of the Cear & acute;a basin, Brazilian Equatorial margin %V 129 %X An organic geochemical investigation combined with sequence stratigraphy was performed in the Cear ` a Basin, an offshore basin located in Northeastern Brazil. The information available from 30 well logs (gamma-ray, resistivity, density), besides geochemical (TOC, and pyrolysis indexes) and isotopic (delta 13C) data, aided the preparation of a dataset for this study. The application of sequence-stratigraphic methods helped classify and correlate seismic and organic facies. Four key petroleum source-rock units were identified, from the oldest to the youngest: (1) Mundau Formation - top of the Rift Sequence (Berriasian-Aptian); (2) Paracuru Formation - Breakup Sequence (Aptian-Albian); (3) Itapaje ` Member of the Ubarana Formation - Continental Drift Sequence (AlbianTuronian), and (4) Uruburetama Member of the Ubarana Formation - Continental Drift Sequence (TuronianMaastrichtian). The geochemical characteristics of the Mundau Formation (high total organic carbon (TOC), hydrogen index (HI), relative hydrocarbon potential (RHP = (S1 + S2)/TOC)) point to a typical transgressive sequence. Six transgressive-regressive (T-R) cycles were recognized in the entire Paracuru Formation. The best geochemical marker is related to the top of the Paracuru Formation. This stratigraphic unit can be correlated to a major anoxic event and is the best source rock of this basin. Evaporitic facies found in this top section, maximum RHP values (anoxic conditions), and maximum flooding surfaces related to transgressive events characterize this interval. Moreover, the wide spatial cover of organic-rich rocks, carbon isotopic data, and the recognition of favorable characteristics for anoxia in other basins of the Equatorial Margin are suggestive of the Aptian-Albian Oceanic Anoxic Event (OAE-1b) occurring in the Cear ` a Basin. The Ubarana Formation represented by the Uruburetama Member and the Itapaje ` Member yields the least promising source rocks. However, high TOC values suggest the occurrence of the late Cenomanian-early Turonian Oceanic Anoxic Event (OAE-2), when organic-rich strata started to deposit in deep-water regions. The predominance of a regressive interval in the Uruburetama Member points to oxic or sub-oxic conditions. Additionally, the correlations between the Brazilian Equatorial Margin and its African counterpart, and the organic geochemical characterization allied to the definition of depositional systems for these regions proved to be useful for oil exploration.

@article{WOS:000656957400001, abstract = {An organic geochemical investigation combined with sequence stratigraphy was performed in the Cear ` a Basin, an offshore basin located in Northeastern Brazil. The information available from 30 well logs (gamma-ray, resistivity, density), besides geochemical (TOC, and pyrolysis indexes) and isotopic (delta 13C) data, aided the preparation of a dataset for this study. The application of sequence-stratigraphic methods helped classify and correlate seismic and organic facies. Four key petroleum source-rock units were identified, from the oldest to the youngest: (1) Mundau Formation - top of the Rift Sequence (Berriasian-Aptian); (2) Paracuru Formation - Breakup Sequence (Aptian-Albian); (3) Itapaje ` Member of the Ubarana Formation - Continental Drift Sequence (AlbianTuronian), and (4) Uruburetama Member of the Ubarana Formation - Continental Drift Sequence (TuronianMaastrichtian). The geochemical characteristics of the Mundau Formation (high total organic carbon (TOC), hydrogen index (HI), relative hydrocarbon potential (RHP = (S1 + S2)/TOC)) point to a typical transgressive sequence. Six transgressive-regressive (T-R) cycles were recognized in the entire Paracuru Formation. The best geochemical marker is related to the top of the Paracuru Formation. This stratigraphic unit can be correlated to a major anoxic event and is the best source rock of this basin. Evaporitic facies found in this top section, maximum RHP values (anoxic conditions), and maximum flooding surfaces related to transgressive events characterize this interval. Moreover, the wide spatial cover of organic-rich rocks, carbon isotopic data, and the recognition of favorable characteristics for anoxia in other basins of the Equatorial Margin are suggestive of the Aptian-Albian Oceanic Anoxic Event (OAE-1b) occurring in the Cear ` a Basin. The Ubarana Formation represented by the Uruburetama Member and the Itapaje ` Member yields the least promising source rocks. However, high TOC values suggest the occurrence of the late Cenomanian-early Turonian Oceanic Anoxic Event (OAE-2), when organic-rich strata started to deposit in deep-water regions. The predominance of a regressive interval in the Uruburetama Member points to oxic or sub-oxic conditions. Additionally, the correlations between the Brazilian Equatorial Margin and its African counterpart, and the organic geochemical characterization allied to the definition of depositional systems for these regions proved to be useful for oil exploration.}, added-at = {2022-05-23T20:00:14.000+0200}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, author = {de Souza, Ana Clara B and do Nascimento Jr, Daniel R and Filho, Francisco Nepomuceno and Batezelli, Alessandro and dos Santos, Felipe H and Oliveira, Karen Leopoldino M and de Almeida, Narelle Maia}, biburl = {https://www.bibsonomy.org/bibtex/257943670d429a25d57fd212ea8728420/ppgfis_ufc_br}, doi = {10.1016/j.marpetgeo.2021.105074}, interhash = {805f4d2ebda3629df4775db12bf40d12}, intrahash = {57943670d429a25d57fd212ea8728420}, issn = {0264-8172}, journal = {MARINE AND PETROLEUM GEOLOGY}, keywords = {Cretaceous Geochemical Relative Transgressive-regressive anoxic events} hydrocarbon markers; potential; sequence; sequences; {Stratigraphic}, publisher = {ELSEVIER SCI LTD}, pubstate = {published}, timestamp = {2022-05-23T20:00:14.000+0200}, title = {Sequence stratigraphy and organic geochemistry: An integrated approach to understand the anoxic events and paleoenvironmental evolution of the Cear & acute;a basin, Brazilian Equatorial margin}, tppubtype = {article}, volume = 129, year = 2021 }