Cenomanian to Coniacian sea-level changes in the Lower Benue Trough (Nkalagu Area, Nigeria) and the Eastern Dahomey Basin: palaeontological and sedimentological evidence for eustasy and tectonism

2019 ◽  
Vol 498 (1) ◽  
pp. 233-255 ◽  
Author(s):  
Holger Gebhardt ◽  
Samuel O. Akande ◽  
Olabisi A. Adekeye
Keyword(s):  
Sea Level ◽  
Deep Water ◽  
Close Relation ◽  
Depositional Environments ◽  
Sea Level Changes ◽  
Foraminiferal Assemblage ◽  
Benue Trough ◽  
Sea Level Fluctuations ◽  
Dahomey Basin ◽  
Lower Benue Trough

AbstractThe Benue Trough formed in close relation to the opening of the South Atlantic and experienced sea-level fluctuations of different magnitudes during the Cenomanian to Coniacian interval. We identify depositional environments from outcrop sections and a drilling as control record. Lines of evidence for the interpretation include facies analyses, foraminiferal assemblage composition (P/B-ratio) and the presence of planktonic deep-water indicators. While the analysis of the well data from the Dahomey Basin indicates a continuous deep-water (bathyal) environment, the succession in the Nkalagu area of the Lower Benue Trough evolved in a different and more complex way. Beginning with latest Cenomanian shoreface to shelf deposits, a long period of subsidence lasted until the middle Turonian when pelagic shales and calcareous turbidites were deposited at upper to middle bathyal depths. These conditions continued during late Turonian and Coniacian times. The general deepening trend of the Lower Benue Trough was mainly controlled by tectonic subsidence and was superimposed by eustatic sea-level changes, resulting in periodically changing palaeowater depths. We were able to identify eight sea-level rises and falls that can be attributed to 405 kyr eccentricity cycles. The amplitudes of the sea-level changes were most likely in the range of several tens to a few hundred metres. The deposition of carbonate turbidites at Nkalagu was probably triggered by eustatic sea-level lowstands.

scholarly journals The Bakken Formation - understanding the sequence stratigraphic record of low-gradient sedimentary systems, shale depositional environments, and sea-level changes in an icehouse world

2020 ◽  
Vol 18 (4) ◽  
pp. 4-9
Author(s):  
Sven O Egenhoff ◽  
Neil S Fishman
Keyword(s):  
Sea Level ◽  
High Amplitude ◽  
Depositional Environments ◽  
Ice Age ◽  
Bakken Formation ◽  
Sea Level Changes ◽  
Sequence Stratigraphic ◽  
Sea Level Fluctuations ◽  
Layer Cake ◽  
Low Amplitude

The Bakken Formation is a major petroleum producer in the continental US. However, its deposition in an intracratonic, low-gradient setting has often been mistakenly described as “layer-cake”. This contribution is designed to highlight the time-transgressive nature of its main petroleum-producer, the middle Bakken member. Correlation of individual parasequences reveal the subtle nature of otherwise invisible low-angle stratigraphic geometries. Sequence stratigraphically-relevant surfaces occur throughout the unit and subdivide the entire Bakken into 5 third-order sequences; one of them is a hidden sequence at the base of the petroleum-producing middle Bakken indicating both a lowstand and a subsequent transgression. The organic-rich shales above and below the middle Bakken were deposited in an oxygen-deficient environment and show several burrow/fecal string types and indications of active currents during deposition. The Bakken records high amplitude sea-level changes during sequences compared to relative low amplitude sea-level changes of parasequences. This, coupled with a likely mismatch in timing of Bakken deposition relative to world-wide ice-age-induced cyclicity makes it unlikely that the Bakken sea-level fluctuations were dominated by glaciation.

scholarly journals Depositional environment of the Branch Sandstone and correlative sequences: Late Cretaceous changes in relative sea level in the East Coast Basin of New Zealand

2021 ◽  
Author(s):  
◽  
Lisa McCarthy
Keyword(s):  
Sea Level ◽  
East Coast ◽  
Depositional Environments ◽  
Passive Margin ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Sea Level Fluctuations ◽  
The North ◽  
Tasman Sea ◽  
History Of

<p>The Branch Sandstone is located within an overall transgressive, marine sedimentary succession in Marlborough, on the East Coast of New Zealand’s South Island. It has previously been interpreted as an anomalous sedimentary unit that was inferred to indicate abrupt and dramatic shallowing. The development of a presumed short-lived regressive deposit was thought to reflect a change in relative sea level, which had significant implications for the geological history of the Marlborough region, and regionally for the East Coast Basin.  The distribution and lithology of Branch Sandstone is described in detail from outcrop studies at Branch Stream, and through the compilation of existing regional data. Two approximately correlative sections from the East Coast of the North Island (Tangaruhe Stream and Angora Stream) are also examined to provide regional context. Depositional environments were interpreted using sedimentology and palynology, and age control was developed from dinoflagellate biostratigraphy. Data derived from these methods were combined with the work of previous authors to establish depositional models for each section which were then interpreted in the context of relative sea level fluctuations.  At Branch Stream, Branch Sandstone is interpreted as a shelfal marine sandstone, that disconformably overlies Herring Formation. The Branch Sandstone is interpreted as a more distal deposit than uppermost Herring Formation, whilst the disconformity is suggested to have developed during a fall in relative sea level. At Branch Stream, higher frequency tectonic or eustatic sea-level changes can therefore be distinguished within a passive margin sedimentary sequence, where sedimentation broadly reflects subsidence following rifting of the Tasman Sea. Development of a long-lived disconformity at Tangaruhe Stream and deposition of sediment gravity flow deposits at Angora Stream occurred at similar times to the fall in relative sea level documented at the top of the Herring Formation at Branch Stream. These features may reflect a basin-wide relative sea-level event, that coincides with global records of eustatic sea level fall.</p>

scholarly journals INVESTIGATION OF THE INTERNAL STRUCTURE AND EVOLUTION OF THE HOLOCENE BARRIER OF MARICÁ (RIO DE JANEIRO, BRAZIL)

2015 ◽  
Vol 33 (3) ◽  
pp. 461
Author(s):  
Carolina Pereira Silvestre ◽  
André Luiz Carvalho da Silva ◽  
Maria Augusta Martins da Silva ◽  
Amilsom Rangel Rodrigues
Keyword(s):  
Internal Structure ◽  
Sea Level ◽  
Ground Penetrating Radar ◽  
Rio De Janeiro ◽  
Depositional Environments ◽  
Sea Level Changes ◽  
The Holocene ◽  
Sea Level Fluctuations ◽  
Sedimentary Architecture ◽  
Ground Penetrating

ABSTRACT. The objective of this study is the identification of the internal structure of the Holocene barrier of the Maricá coastal plain (Rio de Janeiro, Brazil) for the understanding of the evolution of this coast. The regional geomorphology is characterized by the large Maricá lagoon and by two sandy barriers which confines a series of small near-dry lagoons. Geophysical data obtained from ground-penetrating radar (GPR) images, with 400 and 200 MHz shielded antennae and borehole samples, both reaching down to about 10 meters in depth, provided information about the sedimentary architecture and geological and oceanographical processes responsible for the evolution of this area in the Holocene. The results show that the barrier internal structure is formed by a set of strata presenting different geometries, dip directions and organization, relative to the following depositional environments: dunes, washover fans, beach and tidal channels. It was possible to determine the importance of the sea level changes, longshore currents and overwash processes for the barrier development. Strong reflectors representing eolian strata dipping towards the continent point out to a phase of barrier retrogradation; afterwards, a succession of very well preserved beach paleoscarps, located south of the previous barrier, shows a phase of barrier progradation. Such evidences indicate that the barrier evolved according to the Holocene sea level fluctuations recognized for the Brazilian coast.Keywords: ground-penetrating radar, barrier-lagoon system, Holocene, Maricá coast. RESUMO. O presente estudo objetivou identificar a estrutura interna da barreira holocênica buscando compreender a evolução da planície costeira de Maricá (Rio de Janeiro). A geomorfologia regional é caracterizada pela Lagoa de Maricá e duas barreiras arenosas, separadas por pequenas lagunas colmatadas. Dados geofísicos obtidos com um georadar, com antenas de 400 e 200 MHz, e amostras de sondagem geológica, ambos até a profundidade média de 10 metros, forneceram informações sobre a arquitetura sedimentar e os processos geológicos e oceanográficos responsáveis pela evolução desta área no Holoceno. Os resultados mostram que a estrutura interna da barreira é formada por um conjunto de estratos de diferentes geometrias, direções de mergulho e modos de organização relacionados aos seguintes ambientes deposicionais: dunas, leques de arrombamento, praias e canais de maré. Essas características permitiram o entendimento da dinâmica costeira responsável pelo desenvolvimento da barreira, com destaque para as variações do nível do mar, correntes de deriva litorânea e mecanismos de sobrelavagem. Refletores marcantes representando estratos eólicos inclinados para o continente indicam uma fase de retrogradação da barreira; a esse episódio se seguiu um período marcado por sucessivas paleoescarpas de tempestade, localizadas mais ao sul, indicando uma fase de progradação. Essas evidências mostram que a barreira evoluiu de acordo com as fases de transgressão e regressão marinha do Holoceno reconhecidas para o litoral brasileiro.Palavras-chave: georadar, sistema barreira-laguna, Holoceno, litoral de Maricá.

scholarly journals Depositional environment of the Branch Sandstone and correlative sequences: Late Cretaceous changes in relative sea level in the East Coast Basin of New Zealand

2021 ◽  
Author(s):  
◽  
Lisa McCarthy
Keyword(s):  
Sea Level ◽  
East Coast ◽  
Depositional Environments ◽  
Passive Margin ◽  
Sea Level Changes ◽  
Relative Sea Level ◽  
Sea Level Fluctuations ◽  
The North ◽  
Tasman Sea ◽  
History Of

<p>The Branch Sandstone is located within an overall transgressive, marine sedimentary succession in Marlborough, on the East Coast of New Zealand’s South Island. It has previously been interpreted as an anomalous sedimentary unit that was inferred to indicate abrupt and dramatic shallowing. The development of a presumed short-lived regressive deposit was thought to reflect a change in relative sea level, which had significant implications for the geological history of the Marlborough region, and regionally for the East Coast Basin.  The distribution and lithology of Branch Sandstone is described in detail from outcrop studies at Branch Stream, and through the compilation of existing regional data. Two approximately correlative sections from the East Coast of the North Island (Tangaruhe Stream and Angora Stream) are also examined to provide regional context. Depositional environments were interpreted using sedimentology and palynology, and age control was developed from dinoflagellate biostratigraphy. Data derived from these methods were combined with the work of previous authors to establish depositional models for each section which were then interpreted in the context of relative sea level fluctuations.  At Branch Stream, Branch Sandstone is interpreted as a shelfal marine sandstone, that disconformably overlies Herring Formation. The Branch Sandstone is interpreted as a more distal deposit than uppermost Herring Formation, whilst the disconformity is suggested to have developed during a fall in relative sea level. At Branch Stream, higher frequency tectonic or eustatic sea-level changes can therefore be distinguished within a passive margin sedimentary sequence, where sedimentation broadly reflects subsidence following rifting of the Tasman Sea. Development of a long-lived disconformity at Tangaruhe Stream and deposition of sediment gravity flow deposits at Angora Stream occurred at similar times to the fall in relative sea level documented at the top of the Herring Formation at Branch Stream. These features may reflect a basin-wide relative sea-level event, that coincides with global records of eustatic sea level fall.</p>

BIOINDICATORS OF SEA-LEVEL FLUCTUATIONS IN SOUTHEASTERN BRAZIL: NEW DATA AND METHODOLOGICAL REVIEW

Radiocarbon ◽  
2021 ◽  
pp. 1-15
Author(s):  
Julia Caon Araujo ◽  
Kita Chaves Damasio Macario ◽  
Vinícius Nunes Moreira ◽  
Anderson dos Santos Passos ◽  
Perla Baptista de Jesus ◽  
...  
Keyword(s):  
Sea Level ◽  
Late Holocene ◽  
Data Interpretation ◽  
Progressive Increase ◽  
Southeastern Brazil ◽  
Recrystallization Process ◽  
Sea Level Changes ◽  
Sea Level Fluctuations ◽  
Data Gap ◽  
Current Zero

ABSTRACT The vermetidae fossils of Petaloconchus varians, formed by calcium carbonate, associated with their radiocarbon ages, are the most accurate indicators of paleo sea level due to their restricted occupation in the intertidal zone in the rocky shore. However, the recrystallization of minerals can affect these age calculations and, consequently, the interpretation of the data. The aim of this study is to present new indicators of paleo sea-level changes in Southeast Brazil for the last 6000 years contributing to fill the data gap for the late Holocene. The influence of the recrystallization process was successfully resolved using the CarDS protocol, enabling the separation of the original aragonite fraction by density, prior to radiocarbon dating. This avoids the rejuvenation of ages and ensures greater efficiency for data interpretation. Paleo sea-level indicators were able to show a progressive increase in sea level up to the transgressive maximum of 4.15 m in 3700 BP years, followed by a regression to the current zero. This regression seems to have in addition, here we reinforce the reliability of the use of fossil vermetids as indicators of sea-level fluctuations.

scholarly journals High-frequency sea-level changes recorded in deep-water carbonates of the Upper Cretaceous Dol Formation (island of Brač, Croatia)

2010 ◽  
Vol 61 (1) ◽  
pp. 29-38
Author(s):  
Damir Bucković ◽  
Maja Martinuš ◽  
Duje Kukoč ◽  
Blanka Tešović ◽  
Ivan Gušić
Keyword(s):  
Sea Level ◽  
Deep Water ◽  
High Frequency ◽  
Upper Cretaceous ◽  
Distal Part ◽  
Preferential Orientation ◽  
Sea Level Changes ◽  
Carbonate Production ◽  
Fine Grained ◽  
Platform Margin

High-frequency sea-level changes recorded in deep-water carbonates of the Upper Cretaceous Dol Formation (island of Brač, Croatia)The upper part of the Middle Coniacian/Santonian-Middle Campanian deep-water Dol Formation of the island of Brač is composed of countless fine-grained allodapic intercalations deposited in an intraplatform trough. Within the studied section 13 beds can be distinguished, each defined by its lower part built up of dark grey limestone with abundance of branched, horizontally to subhorizontally oriented burrows, and the upper part, in which the light grey to white limestone contains larger burrows, rarely branched, showing no preferential orientation. The lower, dark grey, intensively bioturbated levels are interpreted as intervals formed during high-frequency sea-level highstands, while the upper, light grey-to-white levels are interpreted as intervals formed during the high-frequency sea-level lowstands. Cyclic alternation of these two intervals within the fine-grained allodapic beds is interpreted as the interaction between the amount of carbonate production on the platform margin and the periodicity and intensity of shedding and deposition in the distal part of toe-of-slope environment, which is governed by Milankovitch-band high frequency sea-level changes.

scholarly journals Reconstruction of the depositional sedimentary environment of Oligocene deposits (Qom Formation) in the Qom Basin (northern Tethyan seaway), Iran

Geologos ◽  
2020 ◽  
Vol 26 (2) ◽  
pp. 93-111
Author(s):  
Amrollah Safari ◽  
Hossein Ghanbarloo ◽  
Parisa Mansoury ◽  
Mehran Mohammadian Esfahani
Keyword(s):  
Sea Level ◽  
Sedimentary Environment ◽  
Depositional Environments ◽  
Sea Level Changes ◽  
Third Order ◽  
Depositional Sequences ◽  
Qom Formation ◽  
Tethyan Seaway ◽  
Qom Basin ◽  
Global Sea Level

AbstractDuring the Rupelian–Chattian, the Qom Basin (northern seaway basin) was located between the Paratethys in the north and the southern Tethyan seaway in the south. The Oligocene deposits (Qom Formation) in the Qom Basin have been interpreted for a reconstruction of environmental conditions during deposition, as well as of the influence of local fault activities and global sea level changes expressed within the basin. We have also investigated connections between the Qom Basin and adjacent basins. Seven microfacies types have been distinguished in the former. These microfacies formed within three major depositional environments, i.e., restricted lagoon, open lagoon and open marine. Strata of the Qom Formation are suggested to have been formed in an open-shelf system. In addition, the deepening and shallowing patterns noted within the microfacies suggest the presence of three third-order sequences in the Bijegan area and two third-order depositional sequences and an incomplete depositional sequence in the Naragh area. Our analysis suggests that, during the Rupelian and Chattian stages, the depositional sequences of the Qom Basin were influenced primarily by local tectonics, while global sea level changes had a greater impact on the southern Tethyan seaway and Paratethys basins. The depositional basins of the Tethyan seaway (southern Tethyan seaway, Paratethys Basin and Qom Basin) were probably related during the Burdigalian to Langhian and early Serravallian.

Clay mineral distribution related to rift activity, sea-level changes and paleoceanography in the Cretaceous of the Atlantic Ocean

Clay Minerals ◽  
1993 ◽  
Vol 28 (1) ◽  
pp. 61-84 ◽  
Author(s):  
M. Thiry ◽  
T. Jacquin
Keyword(s):  
Atlantic Ocean ◽  
Sea Level ◽  
Clay Minerals ◽  
Clay Mineral ◽  
Deep Sea ◽  
Depositional Environments ◽  
Sea Level Changes ◽  
Sea Floor ◽  
Deep Sea Sediments ◽  
Bottom Waters

AbstractThe distribution of clay minerals from the N and S Atlantic Cretaceous deep-sea sediments is related to rifting, sea-floor spreading, sea-level variations and paleoceanography. Four main clay mineral suites were identified: two are inherited and indicative of ocean geodynamics, whereas the others result from transformation and authigenesis and are diagnostic of Cretaceous oceanic depositional environments. Illite and chlorite, together with interstratified illite-smectite and smectite occur above the sea-floor basalts and illustrate the contribution of volcanoclastic materials of basaltic origin to the sediments. Kaolinite, with variable amounts of illite, chlorite, smectite and interstratified minerals, indicates detrital inputs from continents near the platform margins. Kaolinite decreases upward in the series due to open marine environments and basin deepening. It may increase in volume during specific time intervals corresponding to periods of falling sea-level during which overall facies regression and erosion of the surrounding platforms occurred. Smectite is the most abundant clay mineral in the Cretaceous deep-sea sediments. Smectite-rich deposits correlate with periods of relatively low sedimentation rates. As paleoweathering profiles and basal deposits at the bottom of Cretaceous transgressive formations are mostly kaolinitic, smectite cannot have been inherited from the continents. Smectite is therefore believed to have formed in the ocean by transformation and recrystallization of detrital materials during early diagenesis. Because of the slow rate of silicate reactions, transformation of clay minerals requires a long residence time of the particles at the water/sediment interface; this explains the relationships between the observed increases in smectite with long-term sea-level rises that tend to starve the basinal settings of sedimentation. Palygorskite, along with dolomite, is relatively common in the N and S Atlantic Cretaceous sediments. It is not detrital because correlative shelf deposits are devoid of palygorskite. Palygorskite is diagnostic of Mg-rich environments and is indicative of the warm and hypersaline bottom waters of the Cretaceous Atlantic ocean.

Subsurface geological imaging of northeastern Tunisia during the middle to the upper Eocene: Insights from integrated geophysical interpretation

2021 ◽  
pp. 1-64
Author(s):  
Oussama Abidi ◽  
Kawthar Sebei ◽  
Adnen Amiri ◽  
Haifa Boussiga ◽  
Imen Hamdi Nasr ◽  
...  
Keyword(s):  
Sea Level ◽  
Regional Scale ◽  
Upper Eocene ◽  
Sea Level Changes ◽  
Seismic Profiles ◽  
Borehole Data ◽  
Third Order ◽  
Good Correspondence ◽  
Basin Inversion ◽  
Sea Level Fluctuations

The Middle to Upper Eocene series are characterized by multiple hiatuses related to erosion, non-deposition or condensed series in the Cap Bon and Gulf of Hammamet provinces. We performed an integrated study taking advantage from surface and subsurface geology, faunal content, borehole logs, electrical well logs, vertical seismic profiles and surface seismic sections. Calibrated seismic profiles together with borehole data analysis reveal unconformities with deep erosion, pinchouts, normal faulting and basin inversion which are dated Campanian, intra-Lutetian and Priabonian compressive phases; these events were also described at the regional scale in Tunisia. Tectonics, sea level fluctuations and climate changes closely controlled the depositional process during the Middle to Upper Eocene time. The depositional environment ranges from internal to outer platform separated by an inherited paleo-high. We determine eight third order sequences characterizing the interaction between tectonic pulsations, sea level changes and the developed accommodation space within the Middle to Upper Eocene interval. We correlate the obtained results of the Cap Bon-Gulf of Hammamet provinces with the published global charts of sea-level changes and we find a good correspondence across third order cycles. Model-based 3D inversion proved to be a solution to model the lateral and vertical lithological distribution of the Middle to Upper Eocene series.

scholarly journals Aquifer-eustasy as the main driver of short-term sea-level fluctuations during Cretaceous hothouse climate phases

2019 ◽  
Vol 498 (1) ◽  
pp. 9-38 ◽  
Author(s):  
Benjamin Sames ◽  
M. Wagreich ◽  
C. P. Conrad ◽  
S. Iqbal
Keyword(s):  
Sea Level ◽  
Phase Relationship ◽  
Sea Level Changes ◽  
Short Term ◽  
Groundwater Levels ◽  
Sequence Stratigraphic ◽  
Sea Level Fluctuations ◽  
Minimum Estimate ◽  
Underlying Mechanisms ◽  
Continental Ice Sheets

AbstractA review of short-term (<3 myr: c. 100 kyr to 2.4 myr) Cretaceous sea-level fluctuations of several tens of metres indicates recent fundamental progress in understanding the underlying mechanisms for eustasy, both in timing and in correlation. Cretaceous third- and fourth-order hothouse sea-level changes, the sequence-stratigraphic framework, are linked to Milankovitch-type climate cycles, especially the longer-period sequence-building bands of 405 kyr and 1.2 myr. In the absence of continental ice sheets during Cretaceous hothouse phases (e.g. Cenomanian–Turonian), growing evidence indicates groundwater-related sea-level cycles: (1) the existence of Milankovitch-type humid-arid climate oscillations, proven via intense humid weathering records during times of regression and sea-level lowstands; (2) missing or inverse relationships of sea-level and the marine δ18O archives, i.e. the lack of a pronounced positive excursion, cooling signal during sea-level lowstands; and (3) the anti-phase relationship of sea and lake levels, attesting to high groundwater levels and charged continental aquifers during sea-level lowstands. This substantiates the aquifer-eustasy hypothesis. Rates of aquifer-eustatic sea-level change remain hard to decipher; however, reconstructions range from a very conservative minimum estimate of 0.04 mm a−1 (longer time intervals) to 0.7 mm a−1 (shorter, probably asymmetric cycles). Remarkably, aquifer-eustasy is recognized as a significant component for the Anthropocene sea-level budget.

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