An Integrated Investigation of Inner-Shelf Strata on the Eel Margin: The Coarse-Grained Portion of a Transgressive Shelf Sequence (Shallow-Water Swath-Mapping Component)

2001 ◽  
Author(s):  
Roger D. Flood
Keyword(s):  
Shallow Water ◽  
Coarse Grained ◽  
Inner Shelf ◽  
Swath Mapping

scholarly journals New Recent foraminiferal genera and species from the lagoon at Madang, Papua New Guinea

1992 ◽  
Vol 11 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Martin R. Langer
Keyword(s):  
New Species ◽  
Shallow Water ◽  
Papua New Guinea ◽  
New Guinea ◽  
Coarse Grained ◽  
New Genera ◽  
Low Oxygen ◽  
Shell Surface ◽  
Sedimentary Environments ◽  
Tropical Lagoon

Abstract. Two new genera and eight new species of benthic foraminifera are described from the shallow water, tropical lagoon of Madang, Papua New Guinea. The new hauerinid genus Pseudolachlanella is characterized by juvenile cryptoquinqueloculine, adult almost massiline arranged chambers, and a slitlike, curved aperture with parallel sides and a long, slender, curved miliolid tooth. Pitella haigi n. gen., n. sp. is a new foraminifera with cryptoquinqueloculine arranged chambers, an almost entirely pitted shell surface (pseudopores) and a rounded aperture with a short simple tooth. Among the other species described as new are four hauerinids and two agglutinated foraminifera All new species described here occur sporadically in the shallow water back- and forereef environments of the lagoon (0–55m), and live infaunally and epifaunally in well-oxygenated, fine and coarse grained biogenic sediments. They are absent in muddy, organic-rich, low-oxygen sedimentary environments within bay inlets where variations of salinity are considerable.

Hardgrounds in the Lower Leintwardine Beds (Silurian) of the Welsh Borderland

1980 ◽  
Vol 117 (4) ◽  
pp. 311-326 ◽  
Author(s):  
Lesley Cherns
Keyword(s):  
Shallow Water ◽  
Aerial Exposure ◽  
Subsequent Removal ◽  
Faunal Assemblage ◽  
Inner Shelf ◽  
Water Conditions ◽  
History Of

SummaryThe base of the Lower Leintwardine Beds (Silurian-Ludlow Series) in the shelf sequences of the Welsh Borderland is marked by a widespread development of shelly conglomeratic limestone beds. Borings into some intraclasts indicate that they were hardgrounds. The early lithification, sometimes in situ, of both sand-grade and mud-grade carbonates is demonstrated by the conglomerates. Some compound intraclasts (‘hiatus concretions’) indicate a complex history of deposition, scouring and lithification. Boring of clasts which have not been further eroded is inferred to have taken place locally. The borings are of the narrow, single entrance form referable to Trypanites. The distribution of the conglomerates relates closely to Leintwardinian palaeogeography. Repeated hardground formation in sequences of inner shelf areas reflects episodic deposition alternating with periods of omission and erosion. There is evidence throughout the shelf of a break in sedimentation with hardground formation at the end of Bringewoodian times. The nature of the conglomerates suggests that they formed in shallow water conditions; there is no lithological indication of sub-aerial exposure. The absence of the Aymestry Limestone in the SE shelf is more probably due to its non-deposition or lateral lithological change to muddier beds with a different faunal assemblage than to its subsequent removal by erosion.

scholarly journals Microfacies and biostratigraphy of an Upper Triassic Dachstein limestone fore-reef block in the Jurassic Sirogojno carbonate-clastic Mélange (Zlatibor Mt., SW Serbia)

2021 ◽  
pp. 3-3
Author(s):  
Oliver Zöhrer ◽  
Gawlick Hans-Jürgen ◽  
George Ples ◽  
Milan Sudar ◽  
Divna Jovanovic
Keyword(s):  
Shallow Water ◽  
Carbonate Platform ◽  
Coarse Grained ◽  
Late Triassic ◽  
Sedimentation Pattern ◽  
Fore Reef ◽  
Calcareous Sponges ◽  
Reef Limestone ◽  
Marine Influence ◽  
Early Late

In the late Middle to early Late Jurassic carbonate-clastic Sirogojno M?lange in the Zlatibor Mountain there is one roughly 35 m thick overturned block with an intact Late Triassic fore-reefal Dachstein Limestone succession that was studied here for its biostratigraphic age, faunal content and microfacies characteristics. The succession starts with coarse-grained rudstones followed by meter-sized reefal blocks intercalated in partly layered resedimented grainstones and packstones with abundant reef-building organisms like calcareous sponges, corals and encrusting organisms. Inside this part of the succession open-marine influenced layers are rare. The succession continues with a partly turbiditic sequence and chaotic rudstones, densely packed with reef-derived material like broken reef-building organisms and shallow-water material like gastropods, bivalves and foraminifers. Grainstones with clear open-marine influence (e.g., thin-shelled bivalves, crinoids, conodonts) appear in between those rudstones, in cases lumachelle layers consisting of halobiids were deposited. To the end of the succession some layers show turbiditic bedding with mixed shallow- water and deep-marine grains and organisms, i.e. filaments and crinoids. On base of conodonts, foraminifers, calcareous algae, holothurians and halobiids throughout the whole studied succession, a Middle Norian (Alaunian) to Rhaetian 1, most probably a Late Norian (Sevatian) age can be assigned to this forereefal Dachstein Limestone succession, with a similar sedimentation pattern like Late Triassic Dachstein fore-reef limestone facies, e.g., in the Northern Calcareous Alps or the eastern Southern Alps. The study of this block in the Sirogojno M?lange closes an important gap in knowledge about the extent, facies and stratigraphy of the Dachstein Carbonate Platform evolution in the Dinarides.

scholarly journals Mississippian (Osagean) Shallow-Water, Mid-Latitude Siliceous Sponge Spicule and Heterozoan Carbonate Facies

2006 ◽  
pp. 1-23
Author(s):  
Evan K. Franseen
Keyword(s):  
North America ◽  
Shallow Water ◽  
Siliceous Sponge ◽  
Inner Shelf ◽  
Sponge Spicule ◽  
Dissolved Silica ◽  
Subaerial Exposure ◽  
Middle Mississippian ◽  
Facies Associations ◽  
Heterozoan Carbonates

Mixtures of biosiliceous and heterozoan-dominated carbonate deposits are commonly interpreted as recording cold-water polar or deep basinal conditions. However, a growing body of literature is documenting examples from the rock record that show these deposits accumulated in shallow-water middle- to low-latitude environments. The continued recognition of ancient neritic heterozoan carbonate and biosiliceous accumulations is broadening our understanding of the various paleoenvironmental controls on their development. Early-Middle Mississippian time was characterized by the development of biosiliceous and carbonate accumulations in North America. This study focuses on Osagean cherty dolomitic strata in cores from the Schaben field in Kansas, which is located in Ness County on the southwest flank of the Central Kansas uplift (CKU). During the Osagean, Kansas was located at approximately 20° S latitude, within the tropical to subtropical latitudinal belt. Study area strata are characterized by shallow-water inner-shelf carbonates that were deposited on a gently southward-sloping shelf (ramp). Two depositional sequences (DS1 and DS2) are identified in cores and are separated by a sequence boundary (SB1) that evidences subaerial exposure. The primary facies in the two depositional sequences include 1) Mudstone-Wackestone (MW); 2) Sponge Spicule-Rich Wackestone-Packstone (SWP); 3) Echinoderm-Rich Wackestone-Packstone-Grainstone (EWPG); and 4) Dolomitic Siltstones and Shale facies. Other features identified in cores include 1) Silica Cementation and Replacement; 2) Silica Replaced Evaporites; 3) Brecciation and Fracturing; and 4) Calcite Cementation and Replacement. The abundance of echinoderm facies with other diverse fauna, evidence of extensive reworking by burrowing organisms, and only rare occurrence of evaporites suggest subtidal deposition in a normal to slightly restricted marine inner-shelf setting for DS1. After the SB1 subaerial exposure event, marine conditions returned but the depositional environment over the study area changed compared to that for much of DS1 deposition. The volumetric increase of sponge-spicule wackestone and packstone (SWP) with less diverse fauna, abundance of early evaporites (replaced by silica), and evidence for shallowest water to subaerially exposed conditions throughout DS2 suggest deposition in more restricted environments that likely ranged from restricted inner shelf/protected embayment to evaporative lagoon and possibly supratidal flat. One of the more significant characteristics in DS2 is the dominance of siliceous sponge spicule facies and heterozoan carbonates that were deposited in shallow-water and restricted environments. This study and others from numerous periods in the geologic record are indicating that shallow-marine, mid-latitude biosiliceous and heterozoan carbonates may be more common than previously thought. Especially interesting are the examples from Mississippian (Osagean-Meramecian) strata in North America that show similar facies associations with DS2 strata of this study. The predominance of Early-Middle Mississippian heterozoan carbonate and biosiliceous (spiculitic) deposits, and lack of photozoan deposits, in the mid-latitude shallow-shelf setting in Kansas and surrounding areas was likely due to abundant nutrients and dissolved silica derived from basinal and/or terrestrial sources. Based on available evidence, upwelling of basinal waters rich in nutrients and dissolved silica appears to have been a primary control on shelf margin and shelf facies. Upwelling even may have had a primary imprint on shallow-water, inner-shelf areas, especially during transgression(s). Nutrients and dissolved silica from terrestrial sources may have contributed to the facies associations in shallowest water, inner-shelf areas. However, the available evidence suggests that terrestrial sourced nutrients and dissolved silica were not the dominant control. The results of this study have implications from a petroleum reservoir standpoint. The DS2 sponge spicule, heterozoan carbonate, and silica-replaced evaporite facies in this study form reservoirs in Schaben field and another nearby field composed of similar facies. Because regional upwelling is likely to have had at least some control, facies similar to DS2 strata may form important reservoirs in Lower-Middle Mississippian strata that were deposited in shallow-water inner shelf/ramp settings elsewhere in Kansas and North America. Continuing studies of the controls on biosiliceous and heterozoan carbonate deposition and diagenesis in mid-latitude neritic settings will improve our understanding and predictive capabilities.

scholarly journals Faunistické společenstvo kroměřížského souvrství na lokalitě Litenčice (karpatská předhlubeň, střední Morava)

2020 ◽  
Vol 27 (1-2) ◽  
Author(s):  
Ruzena Gregorova ◽  
Pavla Tomanová Petrová ◽  
Helena Gilíková ◽  
Slavomír Nehyba ◽  
Rostislav Brzobohatý ◽  
...  
Keyword(s):  
Shallow Water ◽  
Marine Environment ◽  
Middle Part ◽  
Coarse Grained ◽  
Turbidity Currents ◽  
Central Paratethys ◽  
Lower Miocene ◽  
Submarine Slope ◽  
Carpathian Foredeep ◽  
High Dynamics

The fossil assemblages of the foraminifers, bryozoans, molluscs, corals, decapods, sharks and teleosteans were analysed from the Litenčice sand pit in the middle part of the Carpathian Foredeep. The section can be assigned to the Karpatian Stage of the Central Paratethys regional stratigraphy (uppermost Lower Miocene) on the basis of species Uvigerina graciliformis Papp et Turn., Lampanyctus carpaticus (Brz.) and Agapilia pachii (Hoern.). Rich and diversified assemblages indicate mainly shallow water marine environment. Foraminifers and molluscs indicate salinity perturbations. Bryozoans and also molluscs document environment with relatively high dynamics and depth of water about 100 m. Foraminifers, fishes and sharks represent deeper water taxa and indicate a possible reworking of shallow-water elements. The studied sands and gravels of the Holešov Member of the Kroměříž Formation are interpreted as sediments of gravitational currents, more precisely dense turbidity currents (high-density turbidity currents) in the sense of Lowe (1982). The deposition environment can probably be placed on the submarine slope of the coarse-grained delta of the Gilbert type (so-called foresets). This study provided evidence of a number of fossil groups that occur at the site.

Adaptative morphology for living in shallow water environments in spatangoid echinoids*

Zoosymposia ◽  
2012 ◽  
Vol 7 (1) ◽  
pp. 255-265 ◽  
Author(s):  
MASAYA SAITOH ◽  
KEN’ICHI KANAZAWA
Keyword(s):  
Shallow Water ◽  
Functional Morphology ◽  
Japan Sea ◽  
Coarse Grained ◽  
Sediment Surface ◽  
Apical Tuft ◽  
The Japan Sea ◽  
Unstable Environment ◽  
Coarse Grained Sand ◽  
Water Depths

Six spatangoid species living in an area about 1 km2 at depths of 5–18 m were investigated in the Oki-Islands in the Japan Sea. The spatangoids capable of burrowing deeply principally adapt to unstable environment where the sediment surface is disturbed by storms. They are confined to the respective habitats depending on their functional morphology; apical tuft spines and fascioles for respiration, inflated plastron and stern-like postero-ventral shape for deep-burrowing. An excep­tional spatangoid, Lovenia elongata, has specific morphologies for quick burrowing and rapid righting against disturbance of superficial sediment, which make it possible for it to live in fine- to coarse-grained sand at various water depths in spite of its burrowing just below the sediment surface.

scholarly journals Geochemistry and geochronology of the Paleozoic sedimentary rocks in the Shar Khutul area, Central Mongolia

2018 ◽  
pp. 4-21
Author(s):  
Erdenechimeg D ◽  
Oyunchimeg T ◽  
Otgonbaatar D ◽  
Jitka Míková ◽  
Tomurchudur Ch ◽  
...  
Keyword(s):  
Shallow Water ◽  
Sedimentary Rocks ◽  
Thin Layers ◽  
Detrital Zircons ◽  
Source Rocks ◽  
Coarse Grained ◽  
Al2o3 Content ◽  
Oceanic Plate ◽  
Stratigraphic Unit ◽  
Middle Carboniferous

The study area is located in the central part of Tsetserleg terrane in the southwestern margin of the Khangai-Khentey orogenic system. The paper presents new data on geochemistry and geochronology of sedimentary rocks from the Shar Khutul area, where the Tsetserleg terrane consists of Silurian-Devonian oceanic plate stratigraphic unit and Carboniferous shallow water sediment. The Upper Silurian to Middle Devonian Erdenetsogt Formation (S3-D2er), which is an oceanic plate stratigraphic unit, is mainly composed of siliceous siltstone, volcanites, tuffs, quartzite, and cherts. The shallow water sediments are divided into Upper Devonian to Lower Carboniferous Tsetserleg Formation (D3-C1cc) and Lower–Middle Carboniferous Dzargalant Formation (C1-2dz). The Tsetserleg Formation (D3-C1cc) consists of only sedimentary rocks such as bluish-grey sandstones and siltstones, and Lower–Middle Carboniferous Dzargalant Formation (C1-2dz) is principally composed of medium- to coarse-grained, brown-greenish grey sandstones with thin-layers of dark siltstones and gravelites. The SiO2 content of the Shar Khutul area sandstones ranges from 63.85 to 67.95 wt.% and the average content of TiO2 is 0.72 wt.% and Al2O3 content is 14.38 wt.%. The Chemical Index of Alteration (CIA) value ranges from 48.71 to 56.94 and the range of Index of compositional variations (ICV) is from 0.98 to 1.24. Moreover, the samples studied show that most of the sandstones are generally immature and were derived from weakly weathered source rocks. The ratios of Eu/Eu* (0.83), La/Sc (3.81), La/Co (5.30), and Cr/Th (13.81) indicate that the derivation of the Shar Khutul area sandstones from felsic rock sources and confirm the signatures of a felsic igneous provenance and suggest an active continental margin tectonic setting of the source area. The clastic zircons from the medium grained sandstone (Erdenetsogt formation) yield ages between 2.5 Ga and 236 Ma and the detrital zircons exhibit four peak ages at 1.7-2.5 Ga (n = 13), 455-499 Ma (n = 6), 337-382 Ma (n = 13) and 236–250 Ma (n = 5).

Sign in / Sign up

Export Citation Format

Share Document