Six new formations (Gaba, Roumi, Poula, Mbissiri, Lende andKali) are proposed for Cretaceous to Paleogene sediments of the Koum Basin, northern Cameroon. The Koum Basin is one of numerous sedimentary basins lining the West and Central African Rift System and presents a complex evolutionary history involving extensional shearing and compressional events spanning the Cretaceous to Paleogene. Recent discoveries of hydrocarbons in associated basin such as Doba in Chad,motivated exploration of the Koum Basin. However, existing studies of the Koum Basin lack a viable lithostratigraphic framework, which is crucial for ongoing exploration efforts in this basin. The present study integrates lithologic, petrographic and palaeontologic data to map, stack and correlate several outcrop sections across the basin. Facies analysis suggests that deposition occurred in a fluvio-lacustrine palaeodeposional environment. The new units were described following the guidelines of the International Stratigraphic Guide. An updated geologicmap depicts the spatial distribution of the lithostratigraphic units that make up the Koum Basin. Palynomorphs, bivalves and dinosaur footprints are used to date the studied sections.
{"title":"A new lithostratigraphic profile for Cretaceous to Paleogene successions in the West and Central African Rift System, Koum Basin, northern Cameroon","authors":"Junior Agbor-Taku, Olivier Anoh Njoh, Nicoline Ngum Fon, Phebe Ursula Mbafor, Moïse Bessong","doi":"10.29041/strat.20.2.02","DOIUrl":"https://doi.org/10.29041/strat.20.2.02","url":null,"abstract":"Six new formations (Gaba, Roumi, Poula, Mbissiri, Lende andKali) are proposed for Cretaceous to Paleogene sediments of the Koum Basin, northern Cameroon. The Koum Basin is one of numerous sedimentary basins lining the West and Central African Rift System and presents a complex evolutionary history involving extensional shearing and compressional events spanning the Cretaceous to Paleogene. Recent discoveries of hydrocarbons in associated basin such as Doba in Chad,motivated exploration of the Koum Basin. However, existing studies of the Koum Basin lack a viable lithostratigraphic framework, which is crucial for ongoing exploration efforts in this basin. The present study integrates lithologic, petrographic and palaeontologic data to map, stack and correlate several outcrop sections across the basin. Facies analysis suggests that deposition occurred in a fluvio-lacustrine palaeodeposional environment. The new units were described following the guidelines of the International Stratigraphic Guide. An updated geologicmap depicts the spatial distribution of the lithostratigraphic units that make up the Koum Basin. Palynomorphs, bivalves and dinosaur footprints are used to date the studied sections.","PeriodicalId":51180,"journal":{"name":"Stratigraphy","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134982662","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Azadeh Norouzian, Mohammad Vahidinia, Meysam Shafiee Ardestani, Youssef S. Bazeen
The Cretaceous Farrokhi Formation is located in the Khur area of central Iran and yielded a reasonably well-preserved rich planktonic foraminiferal assemblage. This formation consists of 154 m of fossiliferous marl and limestone. The lower and upper bounding surfaces of the Farrokhi Formation are unconformable with the underlying Haftoman Formation and the overlying Chupanan Formation. In this research, 46 planktonic foraminiferal species belonging to 19 genera were identified and resulted in recognition of the following three biozones (from base to top); the Globotruncana aegyptiaca Interval Zone (IZ), the Gansserina gansseri IZ, and the Contusotruncana contusa IZ. This biozonal framework places deposition of the Farrokhi Formation during the late Campanian to early Maastrichtian. Biostratigraphic comparison between the samples for this research and data from three other studied sections within the Farrokhi Formation indicates that the basal and upper boundaries of the formation are time-transgressive and migrate chronologically from north to southeast. Since the first occurrences of Pseudoguembelina palpebra and Rugoglobigerina pennyi mark the latest Campanian worldwide, we approximate the Campanian/Maastrichtian boundary based on the FOs of Trinitella scotti and Rugoglobigerina hexacamerata, and identify the basal Maastrichtian by the last occurrence of Laeviella bollii.
{"title":"Planktonic foraminiferal biostratigraphy of the Farrokhi Formation and determination of the Campanian/Maastrichtian boundary in Central Iran","authors":"Azadeh Norouzian, Mohammad Vahidinia, Meysam Shafiee Ardestani, Youssef S. Bazeen","doi":"10.29041/strat.20.1.04","DOIUrl":"https://doi.org/10.29041/strat.20.1.04","url":null,"abstract":"The Cretaceous Farrokhi Formation is located in the Khur area of central Iran and yielded a reasonably well-preserved rich planktonic foraminiferal assemblage. This formation consists of 154 m of fossiliferous marl and limestone. The lower and upper bounding surfaces of the Farrokhi Formation are unconformable with the underlying Haftoman Formation and the overlying Chupanan Formation. In this research, 46 planktonic foraminiferal species belonging to 19 genera were identified and resulted in recognition of the following three biozones (from base to top); the Globotruncana aegyptiaca Interval Zone (IZ), the Gansserina gansseri IZ, and the Contusotruncana contusa IZ. This biozonal framework places deposition of the Farrokhi Formation during the late Campanian to early Maastrichtian. Biostratigraphic comparison between the samples for this research and data from three other studied sections within the Farrokhi Formation indicates that the basal and upper boundaries of the formation are time-transgressive and migrate chronologically from north to southeast. Since the first occurrences of Pseudoguembelina palpebra and Rugoglobigerina pennyi mark the latest Campanian worldwide, we approximate the Campanian/Maastrichtian boundary based on the FOs of Trinitella scotti and Rugoglobigerina hexacamerata, and identify the basal Maastrichtian by the last occurrence of Laeviella bollii.","PeriodicalId":51180,"journal":{"name":"Stratigraphy","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134982666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The benthic foraminifera assemblage has been described in the limestones outcropped in Kurtalan and Eruh district of Hoya formation which is one of autochthonous units of Arabian Platform (SE Turkey). From the two measured sections, one of them has rare fossil content due to dolomitization (DH-Dodan section),while the other is fairly remarkable in terms of fossil content (EH-Eruh section). The foraminiferal assemblages are represented by Asterigerina rotula (Kaufmann), Operculina ex. gr. gomezi Colom and Bauza, Victoriella conoidea Rutten, Amphistegina sp., Elphidium sp., Peneroplis sp., Carpenteria sp., Stomatorbina sp., miliolid and rotaliid forms and echinoderms, coral fragments in the Dodan section. The foraminiferal assemblages are represented by Nummulites biedai Schaub, Nummulites maximus d’Archiac, Nummulites perforatus de Montfort, Nummulites postfossulatus Sirel and Deveciler, Nummulites praeaturicus Schaub, Assilina exponens (Sowerby), Sphaerogypsina globulus (Reuss), Asterigerina rotula (Kaufmann), Lockhartia cf. hunti Ovey, Neoratlia sp., Operculina sp., Discocyclina sp., Asterocyclina sp., Lockhartia sp., Lenticulina sp., miliolid-rotaliid forms and echinoderms in the Eruh section. The fossil assemblage described shows that the limestones are of Lutetian-Bartonian and this assemblage indicates a very shallow marine deposition environment. This study provides biostratigraphic and stratigraphic data that help to reassess the Eocene geological evolution of the region. Paleobiogeographically, larger benthic foraminiferal assemblages recorded on carbonate platforms in southeastern Turkey show an affinity to Arabian and Middle Eastern platforms.
{"title":"Middle Eocene (Lutetian-Bartonian) larger benthic foraminifera assemblages from Batman and Siirt (Southern Neotethys, SE Turkey): a new assessment","authors":"Derya Sinanoglu","doi":"10.29041/strat.20.1.01","DOIUrl":"https://doi.org/10.29041/strat.20.1.01","url":null,"abstract":"The benthic foraminifera assemblage has been described in the limestones outcropped in Kurtalan and Eruh district of Hoya formation which is one of autochthonous units of Arabian Platform (SE Turkey). From the two measured sections, one of them has rare fossil content due to dolomitization (DH-Dodan section),while the other is fairly remarkable in terms of fossil content (EH-Eruh section). The foraminiferal assemblages are represented by Asterigerina rotula (Kaufmann), Operculina ex. gr. gomezi Colom and Bauza, Victoriella conoidea Rutten, Amphistegina sp., Elphidium sp., Peneroplis sp., Carpenteria sp., Stomatorbina sp., miliolid and rotaliid forms and echinoderms, coral fragments in the Dodan section. The foraminiferal assemblages are represented by Nummulites biedai Schaub, Nummulites maximus d’Archiac, Nummulites perforatus de Montfort, Nummulites postfossulatus Sirel and Deveciler, Nummulites praeaturicus Schaub, Assilina exponens (Sowerby), Sphaerogypsina globulus (Reuss), Asterigerina rotula (Kaufmann), Lockhartia cf. hunti Ovey, Neoratlia sp., Operculina sp., Discocyclina sp., Asterocyclina sp., Lockhartia sp., Lenticulina sp., miliolid-rotaliid forms and echinoderms in the Eruh section. The fossil assemblage described shows that the limestones are of Lutetian-Bartonian and this assemblage indicates a very shallow marine deposition environment. This study provides biostratigraphic and stratigraphic data that help to reassess the Eocene geological evolution of the region. Paleobiogeographically, larger benthic foraminiferal assemblages recorded on carbonate platforms in southeastern Turkey show an affinity to Arabian and Middle Eastern platforms.","PeriodicalId":51180,"journal":{"name":"Stratigraphy","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134982665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Robert W. Scott, Carlton E. Brett, Richard H. Jr. Fluegeman, Brian R. Pratt, Ed Landing
At the 77th Annual Meeting of the North American Commission on Stratigraphic Nomenclature (NACSN), 10 October 2022, Denver, Colorado, the Commission voted to accept the introduction of Chemostratigraphic Units to the North American Stratigraphic Code (NACSN 2021) and revisions to the OVERVIEW section and Articles 2, 61 and 62, the renumbering of Articles 61-97 as Articles 63-99, minor rewording of Articles 68 and 77, and concomitant changes to Tables 1 and 2 and Text-Figure 1. Specific revisions of the Code are indicated in red text. These changes replace all older versions of the specified Articles. An application for this revision (Scott et al. 2020) was published in Stratigraphy more than one year prior to the meeting; thus, the vote on this application for revision follows Article 21 of the Code. The numbering of the Articles here differs from that proposed in Scott et al. (2020) hence new versions of Tables 1 and 2 and Text-Figure 1 are introduced here. These revisions explicitly allow the use of chemostratigraphic Units in formal stratigraphic nomenclature.
在2022年10月10日于科罗拉多州丹佛市举行的第77届北美地层命名委员会(NACSN)年会上，委员会投票通过将化学地层单位引入《北美地层法典》(NACSN 2021)，并对概述部分和第2条、第61条和第62条进行修订，将第61-97条重新编号为第63-99条，对第68条和第77条进行轻微修改，并对表1和表2以及文本图1进行相应修改。本守则的具体修订以红色文字注明。这些更改将替换指定条款的所有旧版本。这次修订的申请(Scott et al. 2020)在会议召开一年多前发表在《地层学》上;因此，对这一修订申请的表决遵循《治罪法》第21条。这里的文章编号与Scott et al.(2020)中提出的不同，因此这里引入了新版本的表1和表2以及文本图1。这些修订明确允许在正式的地层命名中使用化学地层单位。
{"title":"NORTH AMERICAN COMMISSION ON STRATIGRAPHIC NOMENCLATURE Report 15 - Revised Articles 2, 61 and 62 of the North American Stratigraphic Code to Formalize Chemostratigraphic Units","authors":"Robert W. Scott, Carlton E. Brett, Richard H. Jr. Fluegeman, Brian R. Pratt, Ed Landing","doi":"10.29041/strat.20.3.03","DOIUrl":"https://doi.org/10.29041/strat.20.3.03","url":null,"abstract":"At the 77th Annual Meeting of the North American Commission on Stratigraphic Nomenclature (NACSN), 10 October 2022, Denver, Colorado, the Commission voted to accept the introduction of Chemostratigraphic Units to the North American Stratigraphic Code (NACSN 2021) and revisions to the OVERVIEW section and Articles 2, 61 and 62, the renumbering of Articles 61-97 as Articles 63-99, minor rewording of Articles 68 and 77, and concomitant changes to Tables 1 and 2 and Text-Figure 1. Specific revisions of the Code are indicated in red text. These changes replace all older versions of the specified Articles. An application for this revision (Scott et al. 2020) was published in Stratigraphy more than one year prior to the meeting; thus, the vote on this application for revision follows Article 21 of the Code. The numbering of the Articles here differs from that proposed in Scott et al. (2020) hence new versions of Tables 1 and 2 and Text-Figure 1 are introduced here. These revisions explicitly allow the use of chemostratigraphic Units in formal stratigraphic nomenclature.","PeriodicalId":51180,"journal":{"name":"Stratigraphy","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135445449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Harry J. Dowsett, Marci M. Robinson, Kevin M. Foley, Stephen J. Hunter, Aisling M. Dolan, Julia C. Tindall
Global reconstructions of Pliocene climate provide important insights into how the climate system operates under elevated temperatures and atmospheric CO2 levels. These reconstructions have been used extensively in paleoclimate modeling experiments for comparison to simulated conditions, and as boundary conditions. Most previous work focused on the Late Pliocene interval known as the mid Piacenzian Warm Period (mPWP), the interval originally identified by the U.S. Geological Survey Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM) as the PRISM interval or Mid Pliocene Warm Period. The term Mid Pliocene Warm Period is a misnomer due to changes to the geological time scale, and its use should be discontinued. The Pliocene Model Intercomparison Project (PlioMIP), now in its third phase, is expanding to include a focus on the Early Pliocene (Zanclean). PlioMIP3 experiments will allow comparison of environmental and climatic conditions before and after closure of the Central American Seaway (CAS). PlioMIP3 used the annual insolation pattern at the top of the atmosphere to determine time slices in the Zanclean that have orbital configurations that are most similar to modern. Two have been selected by PlioMIP and adopted by PRISM for inclusion in future studies: PRISM5.1 (4.474 Ma) and PRISM5.2 (4.870 Ma). Here we establish the stratigraphic framework for these Early Pliocene time slices and furnish information to help locate these intervals in proxy records of paleoenvironmental data using oxygen isotope stratigraphy, paleomagnetic stratigraphy, biostratigraphy, and biochronology (calibrated planktic foraminifer and calcareous nannofossil events).
{"title":"Early Pliocene (Zanclean) stratigraphic framework for PRISM5/PlioMIP3 time slices","authors":"Harry J. Dowsett, Marci M. Robinson, Kevin M. Foley, Stephen J. Hunter, Aisling M. Dolan, Julia C. Tindall","doi":"10.29041/strat.20.3.02","DOIUrl":"https://doi.org/10.29041/strat.20.3.02","url":null,"abstract":"Global reconstructions of Pliocene climate provide important insights into how the climate system operates under elevated temperatures and atmospheric CO2 levels. These reconstructions have been used extensively in paleoclimate modeling experiments for comparison to simulated conditions, and as boundary conditions. Most previous work focused on the Late Pliocene interval known as the mid Piacenzian Warm Period (mPWP), the interval originally identified by the U.S. Geological Survey Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM) as the PRISM interval or Mid Pliocene Warm Period. The term Mid Pliocene Warm Period is a misnomer due to changes to the geological time scale, and its use should be discontinued. The Pliocene Model Intercomparison Project (PlioMIP), now in its third phase, is expanding to include a focus on the Early Pliocene (Zanclean). PlioMIP3 experiments will allow comparison of environmental and climatic conditions before and after closure of the Central American Seaway (CAS). PlioMIP3 used the annual insolation pattern at the top of the atmosphere to determine time slices in the Zanclean that have orbital configurations that are most similar to modern. Two have been selected by PlioMIP and adopted by PRISM for inclusion in future studies: PRISM5.1 (4.474 Ma) and PRISM5.2 (4.870 Ma). Here we establish the stratigraphic framework for these Early Pliocene time slices and furnish information to help locate these intervals in proxy records of paleoenvironmental data using oxygen isotope stratigraphy, paleomagnetic stratigraphy, biostratigraphy, and biochronology (calibrated planktic foraminifer and calcareous nannofossil events).","PeriodicalId":51180,"journal":{"name":"Stratigraphy","volume":"2016 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135446895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Quantitative analysis of the lower Miocene of Ocean Drilling Program Hole 959A from the West African margin was performed to document all the calcareous nannofossil biostratigraphic events present. Combined with data from previous investigations of the lower Miocene from the tropical Atlantic, this research identifies and tests the viability of markers used in current zonation schemes, recognizes alternative markers for age boundaries, and examines statistically the most probable order of events in the lower Miocene using the Ranking and Scaling method (RASC). In Hole 959A, all major zonal and subzonal boundaries from CN1 to CN4 were identified, except for the boundary between Subzones CN1a and CN1b, using primary and secondary markers from the Okada and Bukry (1980) zonation. In addition, all age boundaries from the Chattian to Langhian stages were recognized or closely estimated using the calcareous nannoplankton markers. The resultant list of events extracted from Hole 959Aalong with events from other seven sites were examined biostratigraphically using RASC. A well threshold of four was selected as an appropriate control parameter, resulting in 22 events in the optimum sequence, 13 of which had a low standard deviation. Furthermore, interpolation of ages of events using Age/Depth model for Hole 959A was examined. The extracted ages provided a reasonable preliminary age estimate for the secondary events.
{"title":"Lower Miocene quantitative calcareous nannofossil biostratigraphy from the Tropical Atlantic","authors":"Waheed A. Albasrawi, David K. Watkins","doi":"10.29041/strat.20.1.02","DOIUrl":"https://doi.org/10.29041/strat.20.1.02","url":null,"abstract":"Quantitative analysis of the lower Miocene of Ocean Drilling Program Hole 959A from the West African margin was performed to document all the calcareous nannofossil biostratigraphic events present. Combined with data from previous investigations of the lower Miocene from the tropical Atlantic, this research identifies and tests the viability of markers used in current zonation schemes, recognizes alternative markers for age boundaries, and examines statistically the most probable order of events in the lower Miocene using the Ranking and Scaling method (RASC). In Hole 959A, all major zonal and subzonal boundaries from CN1 to CN4 were identified, except for the boundary between Subzones CN1a and CN1b, using primary and secondary markers from the Okada and Bukry (1980) zonation. In addition, all age boundaries from the Chattian to Langhian stages were recognized or closely estimated using the calcareous nannoplankton markers. The resultant list of events extracted from Hole 959Aalong with events from other seven sites were examined biostratigraphically using RASC. A well threshold of four was selected as an appropriate control parameter, resulting in 22 events in the optimum sequence, 13 of which had a low standard deviation. Furthermore, interpolation of ages of events using Age/Depth model for Hole 959A was examined. The extracted ages provided a reasonable preliminary age estimate for the secondary events.","PeriodicalId":51180,"journal":{"name":"Stratigraphy","volume":"294 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135446915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sandra Crespo de Cabrera, Thomas de Keyser, Ghaida Al-Sahlan, Hajar A. Al-Wazzan, Adi P. Kadar
This paper summarizes sedimentological and biostratigraphic data for the Minjur and Marrat Formations in Kuwait and places them within an expanded sequence stratigraphic framework based on the letter and number scheme initiated by Sharland and others (2001). Only two sequences (Tr80 and J10) were identified in this interval in the original scheme, whereas, between Tr80 and the top of the Upper Marrat, 18 sequences are now recognized and their sequence boundaries and maximum flooding surfaces identified and illustrated herein. One new sequence (Tr90) was proposed in the underlying Jilh A Member. Three new sequences (Tr100, Tr105 and Tr110) are recognized in the Minjur Formation (= Lower Minjur in Saudi Arabia). Four sequences (J02, J04, J06 and J08) and part of a fifth (J10) are recognized in the Lower Marrat. Seven sequences (part of J10 and J11-J16) are recognized in the Middle Marrat. Three sequences (J17, J18 and J19) are recognized in the Upper Marrat. Biostratigraphic data are sparse for the Minjur and Marrat Formations. In the Marrat Formation, calcareous nannofossils are extremely rare, benthic foraminifers are relatively common but long-ranging and palynomorphs are sparse and most commonly non-age diagnostic. Published and unpublished proprietary data from 33 wells have been combined to determine the ages of the succession. Using palynology, the Minjur Lower Member was dated as Norian. An undifferentiated Norian-Rhaetian age range is assigned to the Middle and upper Members of the Minjur Formation. The Triassic/Jurassic boundary is placed just below the base of the Lower Member of the Marrat Formation, where cuttings samples from a thin interval of strata yielded long age-ranging palynomorphs. The Sinemurian/Pliensbachian boundary occurs in the Lower Marrat at the base of the S J06 transgressive systems tract. The Pliensbachian/Toarcian boundary, dated on the basis of Nannoceratopsis triceras and Lotharingius crucicentralis, is also in the Lower Marrat at the base of the S J10 transgressive systems tract. The contact of the Middle and Upper Marrat is unconformable and locally karsted but appears to correlate to the Toarcian/Aalenian boundary. The upper section of the Upper Marrat and the base of the overlying Dhruma Formation have not been cored but the Aalenian/Bajocian boundary is placed in the upper portion of Sequence J19. SB J20 is placed at the top of the Upper Marrat Member. Change in the age of the Late Triassic Baluti Formation in Iraq has resulted in changes in correlations of the Minjur and Marrat Formations to each other and to other formations in the region. The Lower Marrat is shown to be the shallow marine equivalent of the Upper Minjur siliciclastics in the subsurface Rub al Khali Basin and in the shallow subsurface Arabian Basin near the outcrop belt in Saudi Arabia. The Lower Marrat correlates to the Adaiyah Formation and the Upper Sarki Formation in Iraq. The Middle Marrat correlates to the Mus and Alan Formations in Ir
{"title":"Biostratigraphy and sequence stratigraphy of the Minjur and Marrat Formations (Upper Triassic to Middle Jurassic) in Kuwait","authors":"Sandra Crespo de Cabrera, Thomas de Keyser, Ghaida Al-Sahlan, Hajar A. Al-Wazzan, Adi P. Kadar","doi":"10.29041/strat.20.3.01","DOIUrl":"https://doi.org/10.29041/strat.20.3.01","url":null,"abstract":"This paper summarizes sedimentological and biostratigraphic data for the Minjur and Marrat Formations in Kuwait and places them within an expanded sequence stratigraphic framework based on the letter and number scheme initiated by Sharland and others (2001). Only two sequences (Tr80 and J10) were identified in this interval in the original scheme, whereas, between Tr80 and the top of the Upper Marrat, 18 sequences are now recognized and their sequence boundaries and maximum flooding surfaces identified and illustrated herein. One new sequence (Tr90) was proposed in the underlying Jilh A Member. Three new sequences (Tr100, Tr105 and Tr110) are recognized in the Minjur Formation (= Lower Minjur in Saudi Arabia). Four sequences (J02, J04, J06 and J08) and part of a fifth (J10) are recognized in the Lower Marrat. Seven sequences (part of J10 and J11-J16) are recognized in the Middle Marrat. Three sequences (J17, J18 and J19) are recognized in the Upper Marrat. Biostratigraphic data are sparse for the Minjur and Marrat Formations. In the Marrat Formation, calcareous nannofossils are extremely rare, benthic foraminifers are relatively common but long-ranging and palynomorphs are sparse and most commonly non-age diagnostic. Published and unpublished proprietary data from 33 wells have been combined to determine the ages of the succession. Using palynology, the Minjur Lower Member was dated as Norian. An undifferentiated Norian-Rhaetian age range is assigned to the Middle and upper Members of the Minjur Formation. The Triassic/Jurassic boundary is placed just below the base of the Lower Member of the Marrat Formation, where cuttings samples from a thin interval of strata yielded long age-ranging palynomorphs. The Sinemurian/Pliensbachian boundary occurs in the Lower Marrat at the base of the S J06 transgressive systems tract. The Pliensbachian/Toarcian boundary, dated on the basis of Nannoceratopsis triceras and Lotharingius crucicentralis, is also in the Lower Marrat at the base of the S J10 transgressive systems tract. The contact of the Middle and Upper Marrat is unconformable and locally karsted but appears to correlate to the Toarcian/Aalenian boundary. The upper section of the Upper Marrat and the base of the overlying Dhruma Formation have not been cored but the Aalenian/Bajocian boundary is placed in the upper portion of Sequence J19. SB J20 is placed at the top of the Upper Marrat Member. Change in the age of the Late Triassic Baluti Formation in Iraq has resulted in changes in correlations of the Minjur and Marrat Formations to each other and to other formations in the region. The Lower Marrat is shown to be the shallow marine equivalent of the Upper Minjur siliciclastics in the subsurface Rub al Khali Basin and in the shallow subsurface Arabian Basin near the outcrop belt in Saudi Arabia. The Lower Marrat correlates to the Adaiyah Formation and the Upper Sarki Formation in Iraq. The Middle Marrat correlates to the Mus and Alan Formations in Ir","PeriodicalId":51180,"journal":{"name":"Stratigraphy","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135448773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rajesh Pandey, B. P. Noina, Soumya Jana, A. S. Maurya
High resolution sequence stratigraphy is a useful tool to understand the nature of reservoirs and dispersal patterns in relation to the genesis of these clastic reservoirs. Such analyses are performed by integrating the geophysical (electrolog and seismic) and geological (core and sedimentological) data. This study enables us to understand the nature of reservoirs in the 2nd order Lower to Upper Cretaceous sediments of the Jaisalmer Basin, by configuring it into further higher orders (3rd/4th order). The analysis results in identification of ten depositional facies deposited in the lowstand system tract, the transgressive system tract and the high stand system tract. The log based interpretationswere carried out to identify the 4th order sequences; visual gamma log interpretation supported with CWT indicates eight to nine higher order parasequences within the Pariwar Formation. Similarly, seven higher order sequences were identified within Lower Goru and four in Upper Goru and Parh formations. These identified parasequences will help in petroleum system modelling of the Jaisalmer Basin.
{"title":"High resolution sequence stratigraphy of Lower Cretaceous rocks of the Jaisalmer Basin","authors":"Rajesh Pandey, B. P. Noina, Soumya Jana, A. S. Maurya","doi":"10.29041/strat.20.2.03","DOIUrl":"https://doi.org/10.29041/strat.20.2.03","url":null,"abstract":"High resolution sequence stratigraphy is a useful tool to understand the nature of reservoirs and dispersal patterns in relation to the genesis of these clastic reservoirs. Such analyses are performed by integrating the geophysical (electrolog and seismic) and geological (core and sedimentological) data. This study enables us to understand the nature of reservoirs in the 2nd order Lower to Upper Cretaceous sediments of the Jaisalmer Basin, by configuring it into further higher orders (3rd/4th order). The analysis results in identification of ten depositional facies deposited in the lowstand system tract, the transgressive system tract and the high stand system tract. The log based interpretationswere carried out to identify the 4th order sequences; visual gamma log interpretation supported with CWT indicates eight to nine higher order parasequences within the Pariwar Formation. Similarly, seven higher order sequences were identified within Lower Goru and four in Upper Goru and Parh formations. These identified parasequences will help in petroleum system modelling of the Jaisalmer Basin.","PeriodicalId":51180,"journal":{"name":"Stratigraphy","volume":"364 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134982657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Analysis of fusulinids from the Bug Scuffle Limestone Member of the Gobbler Formation along the western escarpment of the Sacramento Mountains in south-central New Mexico demonstrates that all four Desmoinesian regional fusulinid zones documented in Midcontinent and Southwest North America are present in the stratigraphic unit. Earliest Desmoinesian (Df1 Zone) fusulinids from the basal Bug Scuffle limestone beds suggest that the carbonate unit transgressed northward on the Sacramento Shelf, with Beedeina insolita in basal beds of the southernmost canyon exposures, and the slightly more advanced B. hayensis and B. curta in basal limestone beds of more northern outcrops. Late early Desmoinesian (Df2 Zone) fusulinids are common and widespread throughout the escarpment outcrop belt indicating that it was the time period with the most widespread normal marine shelf paleoenvironmental conditions. The diverse assemblage of the Df2 Zone is characterized by Beedeina novamexicana, B. euryteines, B. leei, B. socorroensis, B. joyitaensis, Wedekindellina euthysepta, and W. excentrica. The microprobematical branching fossil Komia is also common in this zone. Wedekindellina and Komia do not range above the mid-Desmoinesian CSB1 composite sequence boundary. Above that sequence boundary, the early late Desmoinesian Df3 Zone is characterized by sparse Beedeina haworthi, and the closely related B. illinoisensis and B. tumida. The late late Desmoinesian Df4 Zone is represented by a diverse assemblage of fusulinids in the uppermost part of the Bug Scuffle Limestone Member in the southern canyon exposures, including Beedeina acme, B. megista, B. mysticensis, B. lonsdalenesis, B. bellatula, B. gordonensis, and B. vintonensis. No Beedeina identifiable to species were found in upper part of the Bug Scuffle Limestone Member in the northernmost canyon exposures, demonstrating that late Desmoinesian paleoenvironments became more restricted marine northward along the Sacramento Shelf. Above the CSB2 composite sequence boundary in the uppermost Bug Scuffle Limestone Member, the lower part of the uppermost depositional sequence continues to contain latest Desmoinesian Df4 Zone fusulinids in the southern canyon sections. Early Missourian conodonts have been reported in a limestone unit near the top of the Gobbler clastic detrital member in the north-central part of the outcrop belt(Wahlman and Barrick 2018; Lucas et al. 2021), but no early Missourian conodonts or fusulinids have been reported yet from the uppermost Bug Scuffle Limestone Member in the southern canyons.
{"title":"Middle Pennsylvanian (Desmoinesian) Fusulinids of the Bug Scuffle Limestone Member of the Gobbler Formation, Sacramento Mountains, South-Central New Mexico","authors":"Gregory P. Wahlman, Benjamin Rendall","doi":"10.29041/strat.20.2.01","DOIUrl":"https://doi.org/10.29041/strat.20.2.01","url":null,"abstract":"Analysis of fusulinids from the Bug Scuffle Limestone Member of the Gobbler Formation along the western escarpment of the Sacramento Mountains in south-central New Mexico demonstrates that all four Desmoinesian regional fusulinid zones documented in Midcontinent and Southwest North America are present in the stratigraphic unit. Earliest Desmoinesian (Df1 Zone) fusulinids from the basal Bug Scuffle limestone beds suggest that the carbonate unit transgressed northward on the Sacramento Shelf, with Beedeina insolita in basal beds of the southernmost canyon exposures, and the slightly more advanced B. hayensis and B. curta in basal limestone beds of more northern outcrops. Late early Desmoinesian (Df2 Zone) fusulinids are common and widespread throughout the escarpment outcrop belt indicating that it was the time period with the most widespread normal marine shelf paleoenvironmental conditions. The diverse assemblage of the Df2 Zone is characterized by Beedeina novamexicana, B. euryteines, B. leei, B. socorroensis, B. joyitaensis, Wedekindellina euthysepta, and W. excentrica. The microprobematical branching fossil Komia is also common in this zone. Wedekindellina and Komia do not range above the mid-Desmoinesian CSB1 composite sequence boundary. Above that sequence boundary, the early late Desmoinesian Df3 Zone is characterized by sparse Beedeina haworthi, and the closely related B. illinoisensis and B. tumida. The late late Desmoinesian Df4 Zone is represented by a diverse assemblage of fusulinids in the uppermost part of the Bug Scuffle Limestone Member in the southern canyon exposures, including Beedeina acme, B. megista, B. mysticensis, B. lonsdalenesis, B. bellatula, B. gordonensis, and B. vintonensis. No Beedeina identifiable to species were found in upper part of the Bug Scuffle Limestone Member in the northernmost canyon exposures, demonstrating that late Desmoinesian paleoenvironments became more restricted marine northward along the Sacramento Shelf. Above the CSB2 composite sequence boundary in the uppermost Bug Scuffle Limestone Member, the lower part of the uppermost depositional sequence continues to contain latest Desmoinesian Df4 Zone fusulinids in the southern canyon sections. Early Missourian conodonts have been reported in a limestone unit near the top of the Gobbler clastic detrital member in the north-central part of the outcrop belt(Wahlman and Barrick 2018; Lucas et al. 2021), but no early Missourian conodonts or fusulinids have been reported yet from the uppermost Bug Scuffle Limestone Member in the southern canyons.","PeriodicalId":51180,"journal":{"name":"Stratigraphy","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134982659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The establishment of a high-frequency sequence stratigraphic framework (short-term cycles) is the basis of seismic sedimentology research, which provides a new way to establish a high-resolution isochronous stratigraphic framework using 3D-seismic data. The linear interpolation between reference seismic reflections is used to establish a high-resolution isochronous stratigraphic framework (stratal slices). By carefully calibrating time-depth relationships, a corresponding relationship between short-term cycle (high-frequency cycle) interfaces and stratal slices is created. Five reference seismic reflections correspond to maximum flood surfaces. The results show that 311 isochronous stratal slices are formed in the 90 degree phase of the 3D seismic data set. Reference seismic reflection does not change with frequency. The event axis of reference for isochronous seismic reflection often corresponds to the most obvious isochronous interfaces. This method can establish a high-resolution isochronous stratigraphic framework in areas lacking drilling data in a 3D seismic data set. When geological dating data is available, the stratal slices can be further calibrated to absolute geological time, and a paleogeological map can be constructed from the seismic data set. This case study also illustrates the theoretical and practical significance of this method.
{"title":"A method of establishing high-resolution isochronous stratigraphic framework in 3D seismic data volume","authors":"Feng Guo, Changshuan Ji, Shenghua Lai, Lei Zhang","doi":"10.29041/strat.20.2.04","DOIUrl":"https://doi.org/10.29041/strat.20.2.04","url":null,"abstract":"The establishment of a high-frequency sequence stratigraphic framework (short-term cycles) is the basis of seismic sedimentology research, which provides a new way to establish a high-resolution isochronous stratigraphic framework using 3D-seismic data. The linear interpolation between reference seismic reflections is used to establish a high-resolution isochronous stratigraphic framework (stratal slices). By carefully calibrating time-depth relationships, a corresponding relationship between short-term cycle (high-frequency cycle) interfaces and stratal slices is created. Five reference seismic reflections correspond to maximum flood surfaces. The results show that 311 isochronous stratal slices are formed in the 90 degree phase of the 3D seismic data set. Reference seismic reflection does not change with frequency. The event axis of reference for isochronous seismic reflection often corresponds to the most obvious isochronous interfaces. This method can establish a high-resolution isochronous stratigraphic framework in areas lacking drilling data in a 3D seismic data set. When geological dating data is available, the stratal slices can be further calibrated to absolute geological time, and a paleogeological map can be constructed from the seismic data set. This case study also illustrates the theoretical and practical significance of this method.","PeriodicalId":51180,"journal":{"name":"Stratigraphy","volume":"293 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134982658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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