ECOLOGICAL AND TAPHONOMIC FIDELITY IN FOSSIL CRINOID ACCUMULATIONS

Palaios ◽  
2019 ◽  
Vol 34 (11) ◽  
pp. 575-583 ◽  
Author(s):  
DAVID L. MEYER ◽  
WILLIAM I. AUSICH
Keyword(s):  
Depositional Environments ◽  
Biological Processes ◽  
Post Mortem ◽  
Eastern Flank ◽  
South Central ◽  
Middle Mississippian ◽  
Symmetrical Distribution ◽  
Close Proximity ◽  
Marine Facies ◽  
Taphonomic Analysis

ABSTRACT Among fossiliferous marine facies, deposits rich in stalked echinoderms, particularly encrinites, have long been suspected to be susceptible to taphonomic biases because intact calyxes are under-represented or masked by disarticulated skeletal debris. In the middle Mississippian Fort Payne Formation of south-central Kentucky, penecontemporaneous crinoid-rich facies are exposed in close proximity along the shores of Lake Cumberland. Crinoidal packstone buildups preserve a broad preservational spectrum, with articulated crinoid calyxes with arms and columns attached, intact calyxes, holdfasts, and long articulated columns, in a matrix of entirely disarticulated crinoidal fragments. Along a 250 m transect across the flanks and crest of this buildup, identification of 563 specimens of crinoids and blastoids revealed a symmetrical distribution of taxa in which the crest was dominated by disparid and camerate crinoids and the flanks were dominated by camerates. Taphonomic analysis of the same transect showed that intact crinoid calyxes with or without attached arms and column occurred across the entire buildup, but nearly complete specimens with attached arms and column were most common on the western flank and less common on the crest and eastern flank. Taxonomic and taphonomic distributions demonstrate a primary ecologic zonation across the buildup with only localized post-mortem dispersal of crinoids. This is the first demonstration of primary ecologic zonation of a crinoid community preserved within a single lithofacies. Depending on depositional and taphonomic circumstances, crinoids are preserved intact close to their living site; understanding these physical and biological processes provides a significant feedback in reconstructing these ancient depositional environments.

scholarly journals Insights into how environment shapes post-mortem RNA transcription in mouse brain

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Raphael Severino Bonadio ◽  
Larissa Barbosa Nunes ◽  
Patricia Natália S. Moretti ◽  
Juliana Forte Mazzeu ◽  
Stefano Cagnin ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Mouse Brain ◽  
Molecular Mechanisms ◽  
Cell Communication ◽  
Rna Degradation ◽  
The Body ◽  
Biological Processes ◽  
Post Mortem ◽  
Gene Expression Alterations ◽  
Upregulated Genes

AbstractMost biological features that occur on the body after death were already deciphered by traditional medicine. However, the molecular mechanisms triggered in the cellular microenvironment are not fully comprehended yet. Previous studies reported gene expression alterations in the post-mortem condition, but little is known about how the environment could influence RNA degradation and transcriptional regulation. In this work, we analysed the transcriptome of mouse brain after death under three concealment simulations (air exposed, buried, and submerged). Our analyses identified 2,103 genes differentially expressed in all tested groups 48 h after death. Moreover, we identified 111 commonly upregulated and 497 commonly downregulated genes in mice from the concealment simulations. The gene functions shared by the individuals from the tested environments were associated with RNA homeostasis, inflammation, developmental processes, cell communication, cell proliferation, and lipid metabolism. Regarding the altered biological processes, we identified that the macroautophagy process was enriched in the upregulated genes and lipid metabolism was enriched in the downregulated genes. On the other hand, we also described a list of biomarkers associated with the submerged and buried groups, indicating that these environments can influence the post-mortem RNA abundance in its particular way.

Clay mineral variation in Tertiary sediments from the eastern flank of the Niger Delta

Clay Minerals ◽  
1986 ◽  
Vol 21 (2) ◽  
pp. 211-224 ◽  
Author(s):  
S. P. Braide ◽  
W. D. Huff
Keyword(s):  
Clay Mineral ◽  
Niger Delta ◽  
Size Fraction ◽  
Clay Mineralogy ◽  
Burial Diagenesis ◽  
Carbonate Cement ◽  
Eastern Flank ◽  
Marine Facies ◽  
Diagenetic Reactions ◽  
The Relationship

AbstractDetailed clay mineralogical and chemical analyses of well cuttings of Tertiary sediments from two wells, Uruan-1 and Uda-1, on the eastern flank of the Niger delta, have been made in an attempt to investigate clay mineral burial diagenesis. The clay mineralogy indicates a transformation of smectite to an interstratified illite-smectite (I/S) phase. The relationship between ordered and random interlayering, however, is nonsystematic. The chemistry of the <0·1 µm size fraction shows some tendency towards a net gain in K2O and Al2O3 and a net loss in SiO2 with depth, but the relationship does not correlate well with the thermal gradient. The distribution of kaolinite and chlorite in both wells appears to be unrelated in any regular way to smectite transformation and these two minerals are considered to be either the products of other diagenetic reactions affecting various stratigraphic levels, or the result of primary sediment deposition. In well Uda-1, kaolinite decreases in relative abundance with depth. This trend has been interpreted elsewhere as indicative of a transition from nonmarine to marine facies. The results of this study indicate that lack of ion mobility, rather than availability, is a significant factor in retarding the formation of ordered I/S with depth, and that lithology, overpressuring, carbonate cement, and original smectite layer charge may be controlling factors in the smectite → illite transformation.

scholarly journals A new terrestrial palaeoenvironmental record from the Bering Land Bridge and context for human dispersal

2018 ◽  
Vol 5 (6) ◽  
pp. 180145 ◽  
Author(s):  
Matthew J. Wooller ◽  
Émilie Saulnier-Talbot ◽  
Ben A. Potter ◽  
Soumaya Belmecheri ◽  
Nancy Bigelow ◽  
...  
Keyword(s):  
Climate Models ◽  
Environmental Changes ◽  
Land Bridge ◽  
Human Dispersal ◽  
South Central ◽  
Bering Land Bridge ◽  
Last Glaciation ◽  
Close Proximity ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Palaeoenvironmental records from the now-submerged Bering Land Bridge (BLB) covering the Last Glacial Maximum (LGM) to the present are needed to document changing environments and connections with the dispersal of humans into North America. Moreover, terrestrially based records of environmental changes are needed in close proximity to the re-establishment of circulation between Pacific and Atlantic Oceans following the end of the last glaciation to test palaeo-climate models for the high latitudes. We present the first terrestrial temperature and hydrologic reconstructions from the LGM to the present from the BLB's south-central margin. We find that the timing of the earliest unequivocal human dispersals into Alaska, based on archaeological evidence, corresponds with a shift to warmer/wetter conditions on the BLB between 14 700 and 13 500 years ago associated with the early Bølling/Allerød interstadial (BA). These environmental changes could have provided the impetus for eastward human dispersal at that time, from Western or central Beringia after a protracted human population standstill. Our data indicate substantial climate-induced environmental changes on the BLB since the LGM, which would potentially have had significant influences on megafaunal and human biogeography in the region.

THE VALUE OF INTEGRATING BOREHOLE RESISTIVITY IMAGES WITH GEOLOGICAL DATA: RELEVANCE TO HYDROCARBON EXPLORATION

1997 ◽  
Vol 37 (1) ◽  
pp. 301 ◽  
Author(s):  
B. E. J. Messent ◽  
C.M. Yacopetti
Keyword(s):  
Poor Quality ◽  
Depositional Environments ◽  
Hydrocarbon Exploration ◽  
Qualitative Assessment ◽  
Low Permeability ◽  
Geological Data ◽  
Close Proximity ◽  
Potential Reservoir ◽  
Low Permeability Reservoirs ◽  
Selection Of

This paper outlines the contribution borehole resistivity images can make in a frontier exploration program when they are integrated with all available geological data. Specific examples are given from the Duntroon Basin.Dipmeter data and borehole resistivity images can be used to validate seismic structural interpretations. An example is given to show the comparison in interpretation of the different methods.Faults are identified on the borehole images and in addition, qualitative assessment of sealing potential can be made by determining the occurrence and extent of mineralisation. In Greenly-1 the hydrocarbon shows, which are interpreted as migrated hydrocarbons, are found In close proximity to faults identified on borehole images. It is postulated that the faults acted as a conduit for the migrating hydrocarbons. However, these fault planes are now mineralised and interpreted to be sealing. This interpretation is supported by the presence of isolated, over-pressured sandstones.Resistivity images readily identify the orientation of present day horizontal stresses with its implications for fault-trap integrity. However, this is not deemed to be an issue in the Duntroon Basin as there is evidence that at least some of the faults are sealing. Borehole images can also be used to assess caprock integrity by determining the presence or absence of fractures.Within potential reservoir units, borehole resistivity images assist in the interpretation of depositional environments, reservoir geometries and post-depositional changes which affect reservoir quality.Borehole resistivity images provide qualitative interpretations of permeability. It is therefore possible to use the images in the selection of pre-test seats and sampling points in poor quality boreholes or low permeability reservoirs.

scholarly journals The Permian-Triassic boundary in Wyoming: the case of the disappearing paraconformity

1992 ◽  
Vol 6 ◽  
pp. 242-242
Author(s):  
James M. Renner ◽  
Donald W. Boyd
Keyword(s):  
Depositional Environment ◽  
Depositional Environments ◽  
Compelling Evidence ◽  
Carbonate Facies ◽  
Triassic Boundary ◽  
Physical Evidence ◽  
Depositional Processes ◽  
Marine Facies ◽  
Permian Triassic Boundary ◽  
Continuous Deposition

Long-standing interpretations of paleontologic, sedimentologic, and stratigraphic evidence from Permian-Triassic marine sequences in western Wyoming have suggested an interruption in deposition of several million years' duration between the two systems, even though physical evidence of unconformity is subtle and somewhat equivocal. We postulated that an unconformity of this duration should be more pronounced in paralic and non-marine facies in central and southeast Wyoming than in adjacent inner-shelf marine facies in westcentral Wyoming. Therefore, we correlated an erathem boundary-bearing sequence from westcentral Wyoming (where it is faunally controlled) to southeast Wyoming (where it is non-fossiliferous) and studied this sequence for evidence of hiatus. The correlations were made using surface sections, surface gamma-radiation logs, and subsurface log suites.In southeast Wyoming, the lithostratigraphic equivalent to the systemic boundary in westcentral Wyoming is located within a redbed-evaporite sequence traditionally interpreted as having accumulated in paralic and/or terrestrial depositional environments. Physical evidence of disconformity at this surface in southeast Wyoming is no greater, and is in places less, than at several other horizons within the boundary-bearing sequence. Also, petrologic examination of the terrigenous clastic units below, through, and above the boundary-bearing sequence in central and southeast Wyoming suggests notable stability of the depositional environment. Southeastward stratigraphic thinning of various units within this boundary-bearing sequence is demonstrable; however, compelling evidence of regional truncation is not evident, and the stratigraphic thinning appears to be due to primary depositional processes rather than post-depositional erosion during hiatus.We interpret slow, episodic, yet generally continuous deposition of evaporite and siliciclastic units in southeast Wyoming across the Permian-Triassic boundary. If true, then conventional biostratigraphic estimates of the duration of a hiatus separating Permian inner and middle-shelf carbonate facies from overlying Triassic siliciclastics in western Wyoming appear to be overly long, and may need re-evaluation.

scholarly journals Ab-initio binding of barnase–barstar with DelPhiForce steered Molecular Dynamics (DFMD) approach

2020 ◽  
Vol 19 (04) ◽  
pp. 2050016
Author(s):  
Mahesh Koirala ◽  
Emil Alexov
Keyword(s):  
Molecular Dynamics ◽  
Electrostatic Interactions ◽  
3D Structure ◽  
Binding Mode ◽  
Steered Molecular Dynamics ◽  
Biological Processes ◽  
Close Proximity ◽  
Ligand Interactions ◽  
Pulling Force

Receptor–ligand interactions are involved in various biological processes, therefore understanding the binding mechanism and ability to predict the binding mode are essential for many biological investigations. While many computational methods exist to predict the 3D structure of the corresponding complex provided the knowledge of the monomers, here we use the newly developed DelPhiForce steered Molecular Dynamics (DFMD) approach to model the binding of barstar to barnase to demonstrate that first-principles methods are also capable of modeling the binding. Essential component of DFMD approach is enhancing the role of long-range electrostatic interactions to provide guiding force of the monomers toward their correct binding orientation and position. Thus, it is demonstrated that the DFMD can successfully dock barstar to barnase even if the initial positions and orientations of both are completely different from the correct ones. Thus, the electrostatics provides orientational guidance along with pulling force to deliver the ligand in close proximity to the receptor.

Paleobotany and paleoecology of Gao Mine, a late Paleocene fossil locality near Red Deer, Alberta, Canada

2013 ◽  
Vol 50 (3) ◽  
pp. 235-248 ◽  
Author(s):  
Ruth A. Stockey ◽  
Georgia L. Hoffman ◽  
Gar W. Rothwell
Keyword(s):  
Leaf Litter ◽  
Plant Community ◽  
Red Deer ◽  
Depositional Environments ◽  
Overbank Sediments ◽  
Fine Grained ◽  
Plant Fossils ◽  
South Central ◽  
Late Paleocene ◽  
Local Plant

In addition to having a rich assemblage of mammalian fossils, the Gao Mine locality in the Paskapoo Formation of south-central Alberta has yielded numerous plant specimens of late Paleocene (late Tiffanian or Ti5) age. The plant fossils are preserved in siltstones and fine-grained sandstones interpreted as overbank sediments that were deposited on an aggrading floodplain. The assemblage is dominated by the cupressaceous conifer Metasequoia foxii and the cercidiphyllaceous dicot Joffrea speirsiae, including their well-preserved seedlings. The flora also contains foliage of the ferns Onoclea and Speirseopteris and the woody dicots Palaeocarpinus, Aphananthe/Celtis, Aesculus, Beringiaphyllum, ?Trochodendron, and Wardiaphyllum, as well as seedlings of unknown dicotyledonous angiosperms. Metasequoia foxii and Speirseopteris are unique to the floras of Gao Mine and the nearby Munce’s Hill site (Tiffanian Ti4). The remainder of the taxa are common in late Paleocene floras of North Dakota, Montana, and Wyoming, all USA. The floras of the nearby Joffre Bridge Roadcut and Blindman River sites (both Tiffanian Ti3) are more diverse, but both of those sites encompass a wider range of depositional environments and may include higher percentages of allochthonous material. Most of the Gao Mine material is autochthonous. The seedlings were buried in place, along with the surrounding leaf litter, preserving a record of the local plant community.

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