Stratigraphic architecture of climate influenced hyperpycnal mouth bars

Sedimentology ◽  
2021 ◽  
Author(s):  
Ellen M. Melstrom ◽  
Lauren P. Birgenheier
Author(s):  
Bukar Shettima ◽  
Mohammed Bukar ◽  
Fatimoh Dupe Adams

Evaluation of the stratigraphic architecture of the Gombe Formation of the Gongola Sub-basin in the Northern Benue Trough indicated a build-up from six facies assemblage that consist of trough crossbedded sandstone, planar crossbedded sandstone, massive bedded sandstone, ripple laminated sandstone, parallel laminated sandstone and mudstones. These units were packaged into three facies association that constitutes of bedded sandstone facies association (FAgI), interbedded sandstone and mudstone facies association (FAgII) and amalgamated trough crossbedded sandstone facies association (FAgIII). These reflects mouth-bars, pro-delta and delta slope deposits and upper delta plain respectively. This deltaic prism is characterized by unidirectional current system devoid of signatures of tide and waves hydrodynamics in the subaqueous delta regions, thus indicating that the delta system of the Gombe Formation is a fluvial dominated delta.


2015 ◽  
Vol 3 (3) ◽  
pp. SY67-SY81 ◽  
Author(s):  
Xavier Janson ◽  
Keumsuk Lee ◽  
Chris Zahm ◽  
Charles Kerans

Rudist buildups are important reservoirs in many Cretaceous fields in the Middle East, but they are generally near or below seismic resolution. The dimension, shape, and architecture of rudist buildups can be assessed using outcrop, although only partly so because of pseudo-2D observations of geobodies intersecting with the outcrop. We used ground-penetrating radar to enhance our understanding of the shape, dimension, and architecture of Albian rudist buildups in two outcrops in Texas. In the Lake Georgetown spillway, caprinid rudist buildups are 10–30 m wide and 2–7 m high. They are elliptical with an aspect ratio of as much as 1.7. They show no or very little flank development. The older buildup exposed in the Red Bluff Creek area displays 10- to 25-m-wide and 5- to 10-m-high in situ caprinid rudist mound core accumulations with as much as 100-m-wide reworked flanks in the shallower part of the depositional profile. Downdip along the depositional profile, caprinid buildups are 5–20 m wide and 3–7 m high with no flank debris. The buildups in the Lake Georgetown area have similar architecture and comparable size with the downdip buildups exposed in Red Bluff Creek. These buildups were compared with other outcropping Albian buildups in Texas that have different sizes, shapes, and stratigraphic architecture to provide dimensional data that could be used in subsurface reservoir modeling, either for calibrating variogram ranges or to build training images. The rudist buildups exposed in Texas are an order of magnitude smaller than those present in the subsurface in the Middle East, but they have comparable stratigraphic architecture. The size difference might be the result of subsurface buildups being mapped using well-log or core correlations or seismic extractions that cannot resolved at that scale of heterogeneity.


Facies ◽  
2020 ◽  
Vol 67 (1) ◽  
Author(s):  
Franz T. Fürsich ◽  
Matthias Alberti ◽  
Dhirendra K. Pandey

AbstractThe siliciclastic Jhuran Formation of the Kachchh Basin, a rift basin bordering the Malagasy Seaway, documents the filling of the basin during the late syn-rift stage. The marine, more than 700-m-thick Tithonian part of the succession in the western part of the basin is composed of highly asymmetric transgressive–regressive cycles and is nearly unfossiliferous except for two intervals, the Lower Tithonian Hildoglochiceras Bed (HB) and the upper Lower Tithonian to lowermost Cretaceous Green Ammonite Beds (GAB). Both horizons represent maximum flooding zones (MFZ) and contain a rich fauna composed of ammonites and benthic macroinvertebrates. Within the HB the benthic assemblages change, concomitant with an increase in the carbonate content, from the predominantly infaunal “Lucina” rotundata to the epifaunal Actinostreon marshii and finally to the partly epifaunal, partly infaunal Eoseebachia sowerbyana assemblage. The Green Ammonite Beds are composed of three highly ferruginous beds, which are the MFZ of transgressive–regressive cycles forming the MFZ of a 3rd-order depositional sequence. The GAB are highly ferruginous, containing berthieroid ooids and grains. GAB I is characterized by the reworked Gryphaea moondanensis assemblage, GAB II by an autochthonous high-diversity assemblage dominated by the brachiopods Acanthorhynchia multistriata and Somalithyris lakhaparensis, whereas GAB III is devoid of fossils except for scarce ammonites. The GAB are interpreted to occupy different positions along an onshore–offshore transect with increasing condensation offshore. Integrated analyses of sedimentological, taphonomic, and palaeoecological data allow to reconstruct, in detail, the sequence stratigraphic architecture of sedimentary successions and to evaluate their degree of faunal condensation.


Author(s):  
M. O. Fedorovich ◽  
◽  
A. Yu. Kosmacheva ◽  

The present paper describes the DIONISOS software package (Beicip-Technologies), where the reconstruction of the accumulation conditions and facies modeling of sand reservoirs Yu10, Yu9, Yu8, Yu7 and Yu6 of the Tyumenskaya Formation and carbonaceous-clay members acting as fluid seals within the Gerasimovskoye oil and gas condensate field located in the south of the Parabel district of the Tomsk region. Reconstructions of facies environments make it possible to consistently restore conditions and create a general principled model of the accumulation of sandy-argillaceous deposits of the Middle Jurassic PP in a given territory. Polyfacies deposits of the Bajocian are represented by sands of distributaries and stream-mouth bars, underwater slope of delta, above-water and underwater delta plains, argillaceous-carbonaceous sediments of floodplain lakes, bogs, marshes and lagoons, clays formed at the border of the above-water and underwater deltaic plains, silt deposits of above-water and underwater delta plains, prodelta clays. As a result of the 3D facies model construction, it is shown that the subcontinental sedimentary environments of sand reservoirs Yu10–Yu8 are replaced by deltaic and floodplain-lacustrine-boggy ones, and the formation of Yu7–Yu6 reservoirs occurs in conditions of coastal plain, periodically flooded by the sea. In total, 5 lithotypes of sand deposits have been identified, 1 – argillaceous-carbonaceous, 2 – argillaceous and 1 – silty. Computer facies 3D modeling of the sand bodies assemblage (hydrocarbon reservoirs) of the Bajocian age for the Gerasimovskoye oil and gas condensate field has been performed.


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