The Composition of the Facies Types of Clay Seals and Its Change with Depth

2003 ◽  
pp. 147-161
Keyword(s):  
Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 462
Author(s):  
Marcin Krajewski ◽  
Piotr Olchowy

This paper describes and analyzes the Upper Jurassic (Lower Kimmeridgian) succession exposed in the Zakrzówek Horst, located in the Kraków area. Three distinguished facies types FT 1-FT 3 comprise several limestone varieties: sponge-microbial, pelitic-bioclastic, and partly dolomitized detrital-bioclastic. Their sedimentary environments varied from relatively deeper, attaining storm-wave base, to more shallower, probably close to normal-wave base. Characteristic features of limestones are changes in contents of CaCO3 and insoluble residuum as well as porosity values in vertical transitional zones between facies types. The investigated facies types differ in sediment porosity dependent on development of limestones and its susceptibility to mechanical compaction during the early diagenesis. The studied limestones show high CaCO3 contents and minor insoluble residuum contents comprising quartz, chalcedony and clay minerals. No distinct variability occurs in contents of magnesium, silica, alumina and iron accumulated in clay minerals, iron oxides and oxyhydroxides, as well as in the amounts of amorphous silica. Early diagenetic dolomites, which occur locally within the limestones, were unrelated to fracture systems as possible pathways responsible for transfer of solutions rich in Mg2+ ions. The possible source of Mg2+ ions might have been the pore solutions, which migrated from compacted basinal bedded facies towards reef facies or the grain-supported bedded facies developed in the adjacent areas. Microscopic studies revealed dedolomitization at the surfaces and in the inner parts of dolomite crystals. In many cases, dolomite crystals were replaced by calcite forming pseudomorphs.


Facies ◽  
2021 ◽  
Vol 67 (3) ◽  
Author(s):  
Markus Wilmsen ◽  
Udita Bansal

AbstractCenomanian strata of the Elbtal Group (Saxony, eastern Germany) reflect a major global sea-level rise and contain, in certain intervals, a green authigenic clay mineral in abundance. Based on the integrated study of five new core sections, the environmental background and spatio-temporal patterns of these glauconitic strata are reconstructed and some general preconditions allegedly needed for glaucony formation are critically questioned. XRD analyses of green grains extracted from selected samples confirm their glauconitic mineralogy. Based on field observations as well as on the careful evaluation of litho- and microfacies, 12 glauconitc facies types (GFTs), broadly reflecting a proximal–distal gradient, have been identified, containing granular and matrix glaucony of exclusively intrasequential origin. When observed in stratigraphic succession, GFT-1 to GFT-12 commonly occur superimposed in transgressive cycles starting with the glauconitic basal conglomerates, followed up-section by glauconitic sandstones, sandy glauconitites, fine-grained, bioturbated, argillaceous and/or marly glauconitic sandstones; glauconitic argillaceous marls, glauconitic marlstones, and glauconitic calcareous nodules continue the retrogradational fining-upward trend. The vertical facies succession with upwards decreasing glaucony content demonstrates that the center of production and deposition of glaucony in the Cenomanian of Saxony was the nearshore zone. This time-transgressive glaucony depocenter tracks the regional onlap patterns of the Elbtal Group, shifting southeastwards during the Cenomanian 2nd-order sea-level rise. The substantial development of glaucony in the thick (60 m) uppermost Cenomanian Pennrich Formation, reflecting a tidal, shallow-marine, nearshore siliciclastic depositional system and temporally corresponding to only ~ 400 kyr, shows that glaucony formation occurred under wet, warm-temperate conditions, high accumulation rates and on rather short-term time scales. Our new integrated data thus indicate that environmental factors such as great water depth, cool temperatures, long time scales, and sediment starvation had no impact on early Late Cretaceous glaucony formation in Saxony, suggesting that the determining factors of ancient glaucony may be fundamentally different from recent conditions and revealing certain limitations of the uniformitarian approach.


First Break ◽  
2021 ◽  
Vol 39 (3) ◽  
pp. 85-91
Author(s):  
Dona Sita Ambarsari ◽  
Sigit Sukmono ◽  
Ignatius Sonny Winardhi ◽  
Teuku Abdullah Sanny ◽  
Pongga Dikdya Wardaya ◽  
...  

1977 ◽  
Vol 277 (9) ◽  
pp. 1124-1151 ◽  
Author(s):  
A. B. Thompson ◽  
P. T. Lyttle ◽  
J. B. Thompson
Keyword(s):  

2021 ◽  
Author(s):  
Christopher James Banks ◽  
Bohdan Bodnaruk ◽  
Vladislav Kalmutskyi ◽  
Yerlan Seilov ◽  
Murat Zhiyenkulov ◽  
...  

Abstract Context is everything. Not all thick sands pay out and not all thin sands are poorly productive. It is important to understand a basin's palaeogeographical drivers, the resultant palaeoenvironments and their constituent sedimentary architecture. Development of a depositional model can be predictive with respect to the magnitude of accessible pore space for potential development. We present a multi-field study of the Dneipr-Donets basin. Over 600 wells were studied with >4500 lithostratigraphical picks being made. Over 7500 sedimentological picks were made allowing mapping of facies bodies and charting shifts in facies types. A facies classification scheme was developed and applied. The Devonian-Permian sedimentary section records the creation, fill, and terminal closure of the Dneipr-Donets Basin:Syn-rift brittle extension (late Frasnian-Famennian): intracratonic rifting between the Ukrainian Shield and Voronezh Massif formed a NW-SE orientated trough, with associated basaltic extrusion. Basin architecture consists of rotated fault blocks forming graben mini-basins. Sedimentation is dominantly upper shoreface but sand packages are poorly correlatable due to the faulted palaeotopography.Early Post-rift thermal subsidence (Visean-Lower Bashkirian): the faulted palaeotopography was filled and thermal subsidence drove basin deepening. Cyclical successions of offshore, lower shoreface and upper shoreface dominate. Sands are typically thin (<10m) but can be widely correlated and have high pore space connectivity.Mid Post-rift: the Bashkirian (C22/C23 boundary), paralic systems prograde over the shoreface. Changes in vertical facies are abrupt due to a low gradient to basin floor. Deltaic and fluvial facies can produce thick amalgamated sands (>30m), but access limited pore space because they are laterally restricted bodies.Terminal post-rift (Mykytivskan): above the lower Permian, the convergence of the Kazahkstanian and Siberian continents began to restrict the Dnieper-Donets basin's access to open ocean. The basin approached full conditions and deposition was dominated by evaporite precipitation, with periodic oceanic recharge. Ultimately, this sediment records the formation of Pangea. The successions examined were used to construct a basinal relative sea level curve, which can be applied elsewhere in the basin. This can be used to help provide palaeogeographical context to a field, which in turn controls the sedimentary architecture.


Geosciences ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 68 ◽  
Author(s):  
Dorrik Stow ◽  
Zeinab Smillie

The distinction between turbidites, contourites and hemipelagites in modern and ancient deep-water systems has long been a matter of controversy. This is partly because the processes themselves show a degree of overlap as part of a continuum, so that the deposit characteristics also overlap. In addition, the three facies types commonly occur within interbedded sequences of continental margin deposits. The nature of these end-member processes and their physical parameters are becoming much better known and are summarised here briefly. Good progress has also been made over the past decade in recognising differences between end-member facies in terms of their sedimentary structures, facies sequences, ichnofacies, sediment textures, composition and microfabric. These characteristics are summarised here in terms of standard facies models and the variations from these models that are typically encountered in natural systems. Nevertheless, it must be acknowledged that clear distinction is not always possible on the basis of sedimentary characteristics alone, and that uncertainties should be highlighted in any interpretation. A three-scale approach to distinction for all deep-water facies types should be attempted wherever possible, including large-scale (oceanographic and tectonic setting), regional-scale (architecture and association) and small-scale (sediment facies) observations.


2020 ◽  
Vol 90 (7) ◽  
pp. 701-712
Author(s):  
Kasper H. Blinkenberg ◽  
Bodil W. Lauridsen ◽  
Dirk Knaust ◽  
Lars Stemmerik

ABSTRACT The Cenomanian–Danian Chalk Group of NW Europe is characterized by distinct trace-fossil assemblages dominated by Thalassinoides isp., Planolites isp., Zoophycos isp., and Chondrites isp., whereas ichnogenera such as Taenidium and Phycosiphon are rare. The trace fossils form a complex tiering arrangement, which reflects burrowing activities of diverse benthic associations that operate at different levels in the sediment column, dynamic sedimentation rates, and changes in substrate hardness during progressive burial, forming intricate ichnofabrics. In the Danish Basin, studies of chalk ichnofabrics have focused mainly on the Maastrichtian. Studies of the shallower, grain-rich Danian chalk have revealed similar trace-fossil assemblages, whereas the ichnology of the fine-grained, deeper-water Danian deposits is poorly known. Based on detailed facies and ichnofabric analysis of a mid-Danian silica-rich, pelagic chalk located in the central, deeper shelf area of the Danish Basin, four facies types, eight ichnotaxa, and two ichnofabrics are recognized. Most conspicuous and abundant are randomly distributed, variously sized meniscate burrows attributed to Bichordites isp. and Taenidium isp., whereas other common chalk trace fossils are rare or absent. This trace-fossil assemblage outlines two new ichnofabrics in the NW European chalk, which are dominated principally by upper-tier traces. The producer of the abundant Bichordites isp. and Taenidium isp. burrows is identified as a sea urchin on the basis of an exceptionally preserved Bichordites isp. trace aligned with an irregular echinoid body fossil. The identified ichnofabrics controlled early silicification and produced a more complex distribution of silica concretions compared with chalk successions elsewhere. This results in volumetrically thick silica concretion-rich units rather than distinctive silica bands as seen in other Upper Cretaceous and Danian chalk units.


1989 ◽  
Vol 126 (3) ◽  
pp. 249-261 ◽  
Author(s):  
B. Thomson

AbstractArchaean komatiite volcanics at Kambalda, Western Australia have been metamorphosed to upper greenschist–lower amphibolite grade and have experienced intense though heterogeneously developed polyphase deformation. Despite this, preservation of igneous textural features is often good, particularly in areas which underwent only ‘static style’ metamorphism. Thin lavas from the Tripod Hill Member of the Kambalda Komatiite Formation over the western margin of the Hunt nickel shoot display textural elements and facies variations which are virtually identical to those found in fresher thin komatiite sequences in other Archaean greenstone belts. Four principal flow profile (facies) types are defined, comprising nine subtypes. These represent stages in a facies continuum, ranging from ‘mature’ profiles which comprise thick spinifex textured tops and close packed cumulate bases through to massive, jointed ‘immature’ profiles devoid of mesoscopic spinifex texture. The causes of textural diversity within and between profiles are many and complex. However, facies variations can be attributed mainly to the effects of lava velocity at the time of major heat loss, combined with relative lateral position within any flow. The most mature textural (and geochemical) profiles developed in parts of lavas which had become ponded prior to major heat loss, whereas the least evolved profiles developed along the lateral margins (levees) of moving lavas. The study area komatiites occur as alternating stacks of flows of similar type. This stratigraphy records temporal and spatial shifts in the locus of lava ponding over the western margin of the Hunt nickel shoot. Such shifts may have been caused by irregularities in the underlying volcanic topography and/or by synvolcanic faulting and subsidence.


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