SIDERITE AS A CONSTRAINT ON DEPOSITIONAL AND EARLY DIAGENETIC HISTORY: EXAMPLES FROM BARROW SUB-BASIN, NORTH WEST SHELF, WESTERN AUSTRALIA

1998 ◽  
Vol 38 (1) ◽  
pp. 238 ◽  
Author(s):  
G. M. Kraishan ◽  
N. M Lemont
Keyword(s):  
Sea Level ◽  
Early Cretaceous ◽  
Meteoric Water ◽  
Sea Water ◽  
Depositional Environments ◽  
Late Triassic ◽  
Pore Waters ◽  
Sea Level Fluctuations ◽  
Isotopic Studies ◽  
Mn Content

Siderite cement is one of the most volumetrically important diagenetic minerals in the Late Triassic to Early Cretaceous sandstones of the Barrow Sub-basin. It constitutes up to 60 per cent of the rock volume, and where abundant, occludes the primary intergranular porosity. Petrogriiphic, chemical and isotopic studies indicate the early precipitation of much of this siderite prior to significant compaction. Siderite samples and concretions were taken from a variety of depositional environments ranging from fluvial to deep marine from Late Triassic to Early Cretaceous sequences.Of the early phases, three distinct siderite types were recognised and vary according to depositional environment. The first type, mostly collected from fluvial deposits, is Fe-rich with a mean composition of (Fe96.3 Mg1.8 Ca0.9 Mn1.0) C03. The second type of siderite cement is relatively Mg-rich, Ca-poor and has a higher Mn content, with a mean composition of (Fe87.1 Mg9.6 Ca1.2 Mn2.1) C03. The third type of siderite cement is typically Mg−, Ca-rich, with a low Mn content and an average composition of (Fe78.7 Mg12.4 Ca8.4 Mn0.5) C03. The second and third siderite cements occur in marine facies. The δ13C and δ180 values for siderite cements range from −2.8 to −14.3 %. PDB and 17.4 to 28.2 %. SMOW, respectively.Petrographic and chemical isotopic studies and other sedimentological data from siderite can be used to distinguish between different depositional environments. Chemical and isotopic compositions of the early authigenic siderites indicate precipitation from fluids with significant meteoric input. Siderite cements formed during sulphate reduction and early methanogenesis from mixed marine and meteoric pore-waters at temperatures below 30°C. While an influx of meteoric water to the fluvial and deltaic sediments of the Triassic Mungaroo Formation is easily envisaged, the siderites show that some mixing of sea water is also required. The concept of introduction of meteoric water to the marine sediments of the Birdrong Formation requires an appreciation of the sea level fluctuations at the time. In these situations, the recognition of meteoric or marine input to an early siderite cement can assist in the determination of sea level fluctuations.

scholarly journals New data on the Dogger - Cenomanian stratigraphy of Tripolitza series in Central Crete

2018 ◽  
Vol 34 (2) ◽  
pp. 565
Author(s):  
Α. ΖΑΜΠΕΤΑΚΗ - ΛΕΚΚΑ ◽  
Α. ΑΛΕΞΟΠΟΥΛΟΣ
Keyword(s):  
Early Cretaceous ◽  
Late Eocene ◽  
Depositional Environments ◽  
Late Triassic ◽  
Late Paleozoic ◽  
Carbonate Microfacies ◽  
Aegean Islands ◽  
Lower Aptian ◽  
Sedimentation Conditions

Tripolitza series represents the eastern part of the Gavrovo - Tripolitza platform. It outcrops in central and southeastern Peloponnesus, Crete and the Aegean islands. Its stratigraphie column starts with a volcano-sedimentary, clastic sequences (the Tyros beds), of Late Paleozoic to Late Triassic age, followed by a carbonate series of Late Triassic to Late Eocene age and a tertiary flysch. On account of intense dolomitisation as well as of rarity of fossils, the stratigraphy of Tripolitza series is not so well known as the Gavrovo series. Recent investigation attempts to complete the puzzle of Tripolitza's stratigraphie column and to reconstruct the paleogeographic sedimentation conditions. In this paper, we study some stratigraphie sections, which are taken in different places in northern – central Crete(Fig.l). New data about the stratigraphy and the sedimentation conditions of the Tripolitza series during Late Dogger to Cenomanian, complete older ones and provide information about the paleogeographic evolution of the platform. Late Dogger is determinated by Pfenderina salernitana. It is overlain by a carbonate series containing Cladocoropsis mirabilis and Macroporella sellii, dating Early Malm. Early Malm (Oxfordian - Early Kimmeridgian) is characterized by the presence of Cladocoropsis mirabilis, Kurnubia palastiniensis, Neokilianina rahonensis, Parurgonina caelinensis. Late Malm (Late Kimmeridgian - Portlandian) is characterized by Clypeina jurassica and Kurnubia palastiniensis. Early Cretaceous (Valanginian - Barremian) is determinated by Salpingoporella katzeri and Orbitolinopsis capuensis. Early Aptian is determinated by Palorbitolina lenticularis, Salpingoporella dinarica, Debarina hahounerensis, Pseudocyclammina hedbergi. Late(?) Aptian comprises Sabaudia minuta, Cuneolina hensoni, Cuneolina laurentii, Glomospira urgoniana. Albian is characterized by the disappearence of Cuneolina hensoni and Cuneolina laurentii, while Praechrysalidina infracretacea and Cretacicladus minervini are present. Late Albian is determined by the presence of "Coskinolina" bronnimanni. Early Cenomanian is not determinated by characteristic microfossils. Upper Cenomanian is overlain in comformity with upper Albian - lower Cenomanian carbonates. It is characterized by Chrysalidina gradata, Pseudorhapydionina dubia, Pseudorhapydionina laurinensis, Nummoloculina heimi, Broeckina balcanica, Nezzazata gyra, Biconcava bentori, Trochospira anvimelechi. Sedimentation took place in a peritidal environment. We observe alternations of subtidal and intratidal to supratidal conditions of sedimentation. Comparison between the carbonate microfacies of different sections representing synchronous deposits on different places of the platform, show lateral differentiation of depositional environments, from subtidal to supratidal, even supported short and local emersive episodes, (compare lower Aptian deposits of Profitis Ilias and Pinakianou sections, upper Albian deposits of Kythia and Karouzanos sections in present paper, as well as upper Cenomanian deposits of Karouzanos section in this paper, Louloudaki section (ZAMBETAKIS-LEKKAS et al. 1995 and Vitina section ZAMBETAKIS et al. 1988, Varassova section BERNIER & FLEURY 1980, Gavrovo mountain I.G.R.S. & I.F.P. 1966)(Fig.2). Similar sedimentation characterize the perimediterranean platforms during this period (SARTONI & CRESCENTI 1962, DE CASTRO 1962, FARINACCI & RADOICIC 1964, GUSIC 1969, GUSIC, NIKLER & SOKAC 1971, VELIC 1977, CHIOCCHINI et. al.1979, LUPERTO SINNI & MASSE 1993).

Variation in kaolinite morphology with growth temperature in isotopically mixed pore-fluids, Brent Group, UK North Sea

Clay Minerals ◽  
1994 ◽  
Vol 29 (4) ◽  
pp. 591-608 ◽  
Author(s):  
M. Osborne ◽  
R. S. Haszeldine ◽  
A. E. Fallick
Keyword(s):  
Meteoric Water ◽  
Pore Space ◽  
Pore Waters ◽  
The West ◽  
Rock Interaction ◽  
Isotopic Studies ◽  
Reservoir Sandstones ◽  
Oxygen Isotopic ◽  
Low Degrees ◽  
Water Rock Interaction

AbstractDiagenetic kaolinite in reservoir sandstones of the Brent Group precipitated following the dissolution of detrial feldspar. Two distinct morphologies of kaolinite occur: (1) early diagenetic vermiform kaolinite which is often associated with expanded detrital micas; (2) later diagenetic ‘blocky’ kaolinite. Combined hydrogen and oxygen isotopic studies suggest that vermiform kaolinite precipitated at 25–50°C, and blocky kaolinite at 50–80°C, from pore-waters of a similar isotopic composition (δ18O = −6.5 to −3.5‰). These pore-waters are interpreted to be either a mixture of meteoric and compactional waters, or alternatively a meteoric water that had evolved isotopically due to water-rock interaction. Kaolinite precipitation occurred predominantly during the late Cretaceous to early Eocene. Influx of meteoric water into the Brent Group, probably occurred during the Palaeocene. Fluid flow across the entire basin was driven by a hydrostatic head on the East Shetland Platform palaeo-landmass to the west. The development of the two kaolinite morphologies is possibly related to the degree of supersaturation at the time of precipitation. At low degrees of supersaturation, vermiform kaolinite precipitated slowly upon detrital mica surfaces. Blocky kaolinite precipitated more rapidly into open pore-space at higher degrees of supersaturation. Precipitation of blocky kaolinite was perhaps triggered by the decay of oxalate.

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.

Smithian shoreline migrations and depositional settings in Timpoweap Canyon (Early Triassic, Utah, USA)

2014 ◽  
Vol 151 (5) ◽  
pp. 938-955 ◽  
Author(s):  
NICOLAS OLIVIER ◽  
ARNAUD BRAYARD ◽  
EMMANUEL FARA ◽  
KEVIN G. BYLUND ◽  
JAMES F. JENKS ◽  
...  
Keyword(s):  
Sea Level ◽  
High Frequency ◽  
Depositional Environments ◽  
Small Scale ◽  
Early Triassic ◽  
Relative Sea Level ◽  
Depositional Sequence ◽  
Sea Level Fluctuations ◽  
Stacking Pattern ◽  
Shallow Subtidal

AbstractIn Timpoweap Canyon near Hurricane (Utah, USA), spectacular outcrop conditions of Early Triassic rocks document the geometric relationships between a massive Smithian fenestral-microbial unit and underlying, lateral and overlying sedimentary units. This allows us to reconstruct the evolution of depositional environments and high-frequency relative sea-level fluctuations in the studied area. Depositional environments evolved from a coastal plain with continental deposits to peritidal settings with fenestral-microbial limestones, which are overlain by intertidal to shallow subtidal marine bioclastic limestones. This transgressive trend of a large-scale depositional sequence marks a long-term sea-level rise that is identified worldwide after the Permian–Triassic boundary. The fenestral-microbial sediments were deposited at the transition between continental settings (with terrigenous deposits) and shallow subtidal marine environments (with bioturbated and bioclastic limestones). Such a lateral zonation questions the interpretation of microbial deposits as anachronistic and disaster facies in the western USA basin. The depositional setting may have triggered the distribution of microbial deposits and contemporaneous marine biota. The fenestral-microbial unit is truncated by an erosional surface reflecting a drop in relative sea level at the scale of a medium depositional sequence. The local inherited topography allowed the recording of small-scale sequences characterized by clinoforms and short-distance lateral facies changes. Stratal stacking pattern and surface geometries allow the reconstruction of relative sea-level fluctuations and tracking of shoreline migrations. The stacking pattern of these small-scale sequences and the amplitude of corresponding high-frequency sea-level fluctuations are consistent with climatic control. Large- and medium-scale sequences suggest a regional tectonic control.

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.

Evolution of trilobite biofacies in Cambrian basins of the Siberian Platform

2000 ◽  
Vol 74 (6) ◽  
pp. 1000-1019 ◽  
Author(s):  
Tatyana V. Pegel
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Siberian Platform ◽  
Global Scale ◽  
Depositional Environments ◽  
Sign Reversal ◽  
Middle Cambrian ◽  
Upper Cambrian ◽  
Sea Level Fluctuations ◽  
Stratigraphic Succession

Cambrian biotic zonation on the Siberian Platform reflects differentiation of the depositional environments (inner shelf, outer shelf and open basin). The combination of the chart of trilobite biofacies replacement and the curve of sea-level fluctuations shows that trilobite biofacies replacement occurs as a rule at times of sign reversal and distinct change in the rates of sea-level rise or fall. The boundaries of major Siberian platform Cambrian chronostratigraphic units, such a stages and series, frequently coincide with the boundaries of biofacies in stratigraphic succession related to sea-level fluctuations. If these fluctuations are gradual and restricted, then the boundaries of the Cambrian stages and series cannot be isochronous levels at a global scale. The known levels for intercontinental correlation on the Siberian Platform include boundaries of the adjacent Triplagnostus gibbus and Tomagnostus fissus Zones from the uppermost Amganian Stage (Middle Cambrian) and the Glyptagnostus stolidotus and Glyptagnostus reticulatus Zones of the lower Upper Cambrian. Both levels correspond to boundaries between highstands and lowstands on the Siberian Platform and appear to serve as boundaries of high rank. Evolution of the trilobite biofacies zonation is illustrated by genera typical for each of the various Cambrian paleogeographic environments on the Siberian Platform.

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.

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