Tectonic and Eustatic Sea-Level Fluctuations During the Early Cretaceous: A Case Study from the Berriasian–Valanginian Sequences in Saudi Arabia

On the basis of detailed, combined rock-magnetic, lithological, and micropaleontological study of the Mikhailovtsement section of the Moscow syneclise (Ryazan region), the fluctuations in Central Russian Sea level in Callovian–Early Oxfordian were reconstructed. According to the variations of rock-magnetic parameters over the section, seven rock-magnetic intervals were established which correspond to different stages of basin evolution. These stages are compared with sea level fluctuations established on the basis of changes in the lithology of rocks and the ostracod complexes. In general, the nature of sea level change in Callovian–Oxfordian, revealed by combination of the methods during the study of Mikhailovtsement section coincides with global trend.

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

The APPEA Journal ◽

10.1071/aj97012 ◽

1998 ◽

Vol 38 (1) ◽

pp. 238 ◽

Cited By ~ 1

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.

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Episodic dolomitizations driven by sea-level fluctuations in the Permian–Triassic boundary interval: a case study from a dolomitized Changhsingian reef, Shitouzhai section, South China

Carbonates and Evaporites ◽

10.1007/s13146-020-00626-0 ◽

2020 ◽

Vol 35 (3) ◽

Author(s):

Ting Liang ◽

Zhidong Bao ◽

Xiaoer Zhu ◽

Yuxin Guo

Keyword(s):

Sea Level ◽

South China ◽

Triassic Boundary ◽

Sea Level Fluctuations ◽

Permian Triassic Boundary

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Optimum microfossil sequences and cyclic sediment patterns in Early Cretaceous pelagic strata

Canadian Journal of Earth Sciences ◽

10.1139/e93-029 ◽

1993 ◽

Vol 30 (2) ◽

pp. 391-411 ◽

Cited By ~ 2

Author(s):

Felix M. Gradstein ◽

Zehui Huang ◽

Inger L. Kristiansen ◽

James G. Ogg

Keyword(s):

Spectral Analysis ◽

Atlantic Ocean ◽

Sea Level ◽

Early Cretaceous ◽

Lower Cretaceous ◽

Planktonic Foraminifera ◽

Power Spectra ◽

Calcareous Nannofossils ◽

Data Set ◽

Sea Level Fluctuations

Three sequencing methods were used to calculate the most likely biozonation and the periodicity of sedimentary cycles in Lower Cretaceous pelagic strata of the Atlantic and Indian oceans.A database was built of 378 first and last stratigraphic occurrences of calcareous nannofossils, dinocysts, foraminifers, and geomagnetic reversals in highest Jurassic through Lower Cretaceous deep marine strata at 10 Atlantic Ocean and 3 Indian Ocean drilling sites. There are 135 different events in total, about one third of which are unique to either ocean. Using the complete data set, the quantitative stratigraphy methods STRATCOR and RASC calculated closely comparable optimum sequences of average first- and last-occurrence positions. The preferred zonal solution, based on the STRATCOR method, includes 56 events, each of which occurs at three or more sites. The events comprise 6 geomagnetic reversals, 25 nannofossils, 5 planktonic foraminifera, 8 benthic foraminifera, and 12 dinocysts occurrences. Nine assemblage zones have been recognized of Tithonian through Albian age. All but 2 of 18 nannofossil events in the Atlantic Ocean optimum sequence were reported in the same stratigraphic order in a standard Mesozoic nannofossil zonation.Our quantitative examination, using Walsh spectral analysis, of the Lower Cretaceous cyclic sequences at three Deep Sea Drilling Project (DSDP) sites in the Atlantic Ocean generally supports the hypothesis that they are the product of cyclic climatic changes controlled by the Milankovitch orbital cycles. The peaks in the power spectra usually can be related to obliquity and precession cycles; some peaks seem to correspond to the eccentricity cycle. Obliquity seems to be the most important and persistent orbital element responsible for cyclic sedimentation in the Early Cretaceous Atlantic Ocean.The actual pelagic sedimentation rates were calculated for some cores using the results of spectral analysis. The correlation of the actual pelagic sedimentation rate with cyclic patterns and the occurrence of calcareous turbidites indicate that the changes in cycle pattern are the reflection of changes in the oceanographic setting. The changes in oceanographic setting are related to relative-sea-level fluctuations. The intervals dominated by laminated limestone were deposited during higher sea-level periods.

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