Godwin Okumagbe Aigbadon, Ezekiel Obinna Igwe, Obinna Chigoziem Akakuru, Azuka Ocheli, Brume Overare, Ikenna Arisi Obasi, Ernest Orji Akudo, Nosa Samuel Igbinigie, Mu’awiya Baba Aminu
{"title":"Sedimentological, palynostratigraphic investigation and paleoenvironmental reconstruction of the Chad Formation, Bornu (Chad) Basin Nigeria","authors":"Godwin Okumagbe Aigbadon, Ezekiel Obinna Igwe, Obinna Chigoziem Akakuru, Azuka Ocheli, Brume Overare, Ikenna Arisi Obasi, Ernest Orji Akudo, Nosa Samuel Igbinigie, Mu’awiya Baba Aminu","doi":"10.1007/s10933-023-00308-6","DOIUrl":null,"url":null,"abstract":"<p>Sedimentological and palynostratigraphy studies were used to evaluate sediment-stacking patterns in a depth range between 400 and 50 m in the Kemar-1 well section, Bornu (Chad) Basin, Nigeria. The greyish-sandy claystone, rich micaceous, lithified, and unlithified greyish claystone, dark well sorted micaceous sandstone, and poorly sorted and heterolithic clayey sandstones are the major facies components recognised in the well sections. The lithofacies characteristics were used to delineate and assign depositional environments ranging from lacustrine to fluvial settings. Paleoecological results revealed that the dominant palynofloral associations are angiosperm pollen and pteridophytic spores and they were tentatively grouped under three ecological groups which include freshwater, mangrove/brackish and savannah depositional environments in wet to dry climatic conditions during sediment formation. The presence of <i>Echitricolporites spinosus</i> was used to define the <i>Echitricolporites spinosus</i> palynological zone. The basal section at 390–385 m interval in the well shows the dominance of <i>Psilatricolporites crassus</i>, <i>Verrucastosporites usmensis</i>, and <i>Monoporites annulatus</i>, which marked the Eocene boundary from the overlying Miocene marker bed species of <i>Echitricolporites spinosus</i>, <i>Grimsdalea magnaclavata</i>, <i>Anthocerus</i> sp., <i>Nymphaea lotus</i>, and <i>Retistephanocolpites gracilis</i>. The palynomorph data and lithological characteristics from the studied well section have been used to establish that the Chad Formation is of late Eocene to early Miocene age, and that it unconformably overlies the Kerri–Kerri Formation that was deposited in varying lacustrine, fluvial and prograding shoreface and deltaic settings. This study has resolved the controversy surrounding the age of the Chad Formation, the challenge in depositional environment reconstruction. Finally, the stratigraphic framework of the Chad Formation in the study area is presented.</p>","PeriodicalId":16658,"journal":{"name":"Journal of Paleolimnology","volume":null,"pages":null},"PeriodicalIF":1.7000,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Paleolimnology","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1007/s10933-023-00308-6","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Sedimentological and palynostratigraphy studies were used to evaluate sediment-stacking patterns in a depth range between 400 and 50 m in the Kemar-1 well section, Bornu (Chad) Basin, Nigeria. The greyish-sandy claystone, rich micaceous, lithified, and unlithified greyish claystone, dark well sorted micaceous sandstone, and poorly sorted and heterolithic clayey sandstones are the major facies components recognised in the well sections. The lithofacies characteristics were used to delineate and assign depositional environments ranging from lacustrine to fluvial settings. Paleoecological results revealed that the dominant palynofloral associations are angiosperm pollen and pteridophytic spores and they were tentatively grouped under three ecological groups which include freshwater, mangrove/brackish and savannah depositional environments in wet to dry climatic conditions during sediment formation. The presence of Echitricolporites spinosus was used to define the Echitricolporites spinosus palynological zone. The basal section at 390–385 m interval in the well shows the dominance of Psilatricolporites crassus, Verrucastosporites usmensis, and Monoporites annulatus, which marked the Eocene boundary from the overlying Miocene marker bed species of Echitricolporites spinosus, Grimsdalea magnaclavata, Anthocerus sp., Nymphaea lotus, and Retistephanocolpites gracilis. The palynomorph data and lithological characteristics from the studied well section have been used to establish that the Chad Formation is of late Eocene to early Miocene age, and that it unconformably overlies the Kerri–Kerri Formation that was deposited in varying lacustrine, fluvial and prograding shoreface and deltaic settings. This study has resolved the controversy surrounding the age of the Chad Formation, the challenge in depositional environment reconstruction. Finally, the stratigraphic framework of the Chad Formation in the study area is presented.
期刊介绍:
The realization that a historical perspective is often useful, if not essential, to the understanding of most limnological processes has resulted in the recent surge of interest in paleolimnology. The main aim of the Journal of Paleolimnology is the provision of a vehicle for the rapid dissemination of original scientific work dealing with the reconstruction of lake histories. Although the majority of papers deal with lakes, paleoenvironmental studies of river, wetland, peatland and estuary systems are also eligible for publication.
The Journal of Paleolimnology, like the subject itself, is multidisciplinary in nature, and papers are published that are concerned with all aspects (e.g. biological, chemical, physical, geological, etc.) of the reconstruction and interpretation of lake histories. Both applied and more theoretical papers are equally encouraged. The Journal of Paleolimnology will continue to be a major repository for papers dealing with climatic change, as well as other pressing topics, such as global environmental change, lake acidification, eutrophication, long-term monitoring, and other aspects of lake ontogeny. Taxonomic and methodological papers are also acceptable provided they are of relatively broad interest. New equipment designs are frequently featured. In addition to original data and ideas, the Journal of Paleolimnology also publishes review articles, commentaries and program announcements. A relevant Book Review Section is also featured.