Siltstone

In this article a group of hard stone objects will be presented. They were found in various parts and phases of a late Middle Kingdom settlement quarter at the Delta site of Tell el-Daba. The relevant local Phases are G/4 and G/3-1 (c. 1770-1710 BC), about two generations before the onset of the so-called ‘Hyksos’ period in the Egyptian Nile Delta. The macroscopic appearance of the objects seems reasonably similar to warrant the presentation as a group. As these objects were found in the stoneless Delta they had been brought to the site from the Nile valley either in the form of raw material or as finished products. Frequently such objects remain without known provenance. Partly this is the reason why they are in general rarely published and discussed, especially from settlements. Thus, almost no comparative corpus exists for the late Middle Kingdom.

This thesis describes an investigation of the possibilities to measure ground-mass and especially joint parameters (joint direction and joint density) for engineering purposes by means of seismic waves. Therefore a literature study and a field investigation in the United Kingdom were done. The results show that seismic wave behaviour in one ground-mass can vary widely as result of an anisotropic ground-mass, where the anisotropic character is caused by orientated discontinuities, e.g. jointing, and that fan-shooting can be a very useful method to determine these anisotropic groundmass parameters. In some cases it even is a necessary measuring method in order to determine the proper number of ground-mass layers.

FOR CITATIONS:
SALEM, H.S. Computer modeling of porosity and lithology for complex reservoirs using well-log measurements.
Energy Sources: Part A: Recovery, Utilization and Environmental Effects. 2000, Volume 22, Issue 6, Pages: 515-524 (10 p).
Taylor & Francis (Publisher). http://www.tandfonline.com/doi/abs/10.1080/00908310050013749#.UxcenT-Sy-k

ABSTRACT:
The high degree of heterogeneity, saturation of multiphase fluids, and presence of clays in complex reservoirs make each of the three porosity logs (sonic, density, and neutron), if used independently, generally record inaccurate porosity. For such
reservoirs, combining different logs gives accurate results of porosity. The reservoirs of Terra Nova and Hibernia (Jeanne d’Arc Basin), offshore of the eastern coast of Canada, are saturated with multiphase fluids, enriched with clays, and made of
compacted and heterogeneous rocks, in terms of the lithological and mineralogical composition, and the size and shape of the grains and pores. In this study, the porosity and the rock constituents were determined for both reservoirs using a
computer technique in which the iteration process was applied. That was done by developing and using various computer programs and models, and utilizing numerous data from several logs analyzed at 0.2-m sampling-depth intervals. The more the
number of logs and iterations used in computation, the higher the degree of accuracy of results obtained. The reservoirs are made of shalestone, sandstone, siltstone, limestone, marlstone, and conglomerate. The porosity varies widely, because of variations in the rock composition and overburden pressure. The modeled porosity was compared to the porosity measured by the compensated neutron log (CNL). The results indicate that the CNL-m easured porosity is generally higher than the modeled
porosity by about 50%. The CNL-m easurements are greatly affected by the high amount of hydrogen that is chemically bound in the shales, hydrocarbons, and water. Therefore, CNL records higher values of porosity when porosity is actually
low, and lower values of porosity when it is actually high.

A new basal actinopterygian fish, Donnrosenia schaefferi gen. et sp. nov., is described from the Middle Devonian (Givetian) Aztec Siltstone of southern Victoria Land, Antarctica. Donnrosenia gen. nov. is characterized by the large parietals which are of almost equivalent size to the frontals, very small
intertemporals, a small accessory operculum situated dorsally to the prominent anterodorsal process of the suboperculum, a deep dentary with anterior flexure, porous ornamentation on the clavicle, an elongate body form with macromeric squamation, an absence of paired fringing fulcra on the fins, and pectoral lepidotrichia which are unsegmented for much of their length. A phylogenetic analysis based on dermalskeletal features of Devonian actinopterygians indicates that Donnrosenia gen. nov. is the sister taxon to Howqualepis from the Middle Devonian of Victoria, Australia, and is embedded within a possible clade containing the actinopterygians from the Gogo Formation, Western Australia. This supports the concept of an endemic radiation of East Gondwanan actinopterygians, and reinforces the already strong biogeographical similarities between the Middle Devonian palaeofaunas of Australia and Antarctica.

Co-genetic debrite–turbidite beds are most commonly found in distal basin-plain settings and basin margins. This study documents the geometry, architectural association and paleogeographic occurrence of co-genetic debrite–turbidite beds in the Carboniferous Ross Sandstone with the goal of reducing uncertainty in the interpretation of subsurface data in similarly shaped basins where oil and gas is produced.The Ross Sandstone of western Ireland

ABSTRACT. A new species of the arthrodire genus Groenlandaspis is described from the upper part of the Evieux Formation (Upper Famennian), based on several specimens collected from quarries at Modave and Villers-le-Temple, Liège Province, Belgium. It is the first ...

Conservative solute injections were conducted in three first-order montane streams of different geological composition to assess the influence of parent lithology and alluvial characteristics on the hydrological retention of nutrients. Three study sites were established: (1) Aspen Creek, in a sandstone-siltstone catchment with a fine-grained alluvium of low hydraulic conductivity (1·3×10-4 cm/s), (2) Rio Calaveras, which flows through volcanic tuff with alluvium of intermediate grain size and hydraulic conductivity (1·2×10-3 cm/s), and (3) Gallina Creek, located in a granite/gneiss catchment of coarse, poorly sorted alluvium with high hydraulic conductivity (4·1×10-3 cm/s). All sites were instrumented with networks of shallow groundwater wells to monitor interstitial solute transport. The rate and extent of groundwater-surface water exchange, determined by the solute response in wells, increased with increasing hydraulic conductivity. The direction of surface water-groundwater interaction within a stream was related to local variation in vertical and horizontal hydraulic gradients. Experimental tracer responses in the surface stream were simulated with a one-dimensional solute transport model with inflow and storage components (OTIS). Model-derived measures of hydrological retention showed a corresponding increase with increasing hydraulic conductivity.To assess the temporal variability of hydrological retention, solute injection experiments were conducted in Gallina Creek under four seasonal flow regimes during which surface discharge ranged from baseflow (0·75 l/s in October) to high (75 l/s during spring snowmelt). Model-derived hydrological retention decreased with increasing discharge.The results of our intersite comparison suggest that hydrological retention is strongly influenced by the geologic setting and alluvial characteristics of the stream catchment. Temporal variation in hydrological retention at Gallina Creek is related to seasonal changes in discharge, highlighting the need for temporal resolution in studies of the dynamics of surface water-groundwater interactions in stream ecosystems.

In an effort to understand the present-day thermal structure of the Jeanne d'Arc Basin, we derive matrix thermal conductivity values, using a geometric mean model, from thermal conductivity values of thirteen lithologic end-members (of which seven are measurements on materials from the Jeanne d'Arc Basin) and lithological data. Temperature corrections to thermal conductivity are made for both matrix and pore water. In-situ thermal conductivities were obtained after correcting for the effect of porosity, which we estimated from both lithological information and digital well logs. Calculated thermal conductivities of the formations range from 1.46 to 2.65 W m -1K -1. The heterogeneity of formation thermal conductivity is caused by at least two factors. The first is lithological variation due to facies change. The second is due to different degrees of compaction. Under-compacted intervals (overpressure zones) are characteristically of lower thermal conductivity. The surface heat flow density calculated with an inverse method in seventeen wells varies from 37.8 to 60.7 mW/m 2. This study indicates that surface heat flow density values estimated without porosity corrections may be 15% higher than those with porosity corrections. We also demonstrate the sensitivity of modelled timing of maturation to thermal conductivity estimations.

Geoarchaeological research at the Knife Lake quarries on the U.S. side of the international border was
conducted to understand the geological context of the archaeological sites. Previous geological research
focused on broad, large-scale patterns rather than the detailed, fine-scale investigations relevant to archaeological
research. The quarry bedrock is very complex in origin, with varied sedimentary deposition
of volcanics subjected to later metamorphic events. The Wendt and Lillian Joyce quarries contain multiple
layers of siltstone and greywacke; cultural use focused on specific siltstone layers of the best types for knapping,
producing several bedrock quarry features where the rock was intensively removed. Experimental
flintknapping then confirmed the superiority of medium to fine texture siltstone over coarser siltstone for
producing bifaces. The site geology informs the cultural patterns and provides a structure for understanding
the archaeological materials at each site.

Un nouvel Arthrodire Groenlandaspidide (Vertebrata: Placodermi) du Famennien de Belgique. Une nouvelle espece du genre d'Arthrodire Groenlandaspis est decrite sur la base de plusieurs specimens recoltes dans la partie superieure de la Formation d'Evieux (Famennien superieur), dans les carrieres de Modave et Villers-le-Temple, Province de Liege, Belgique. Il s'agit de la premiere mention de ce genre en Europe continentale, par ailleurs largement repandu. Cette nouvelle espece est caracterisee par une cuirasse dermique pratiquement depourvue d'ornementation, sauf sur les plaques du toit crânien et les plaques mediane dorsale et spinale. Sa plaque mediane dorsale est triangulaire et presque parfaitement equilaterale en vue laterale et porte de grands denticules spiniformes sur son bord posterieur. Ces restes de Groenlandaspis sont conserves dans un claystone ou siltstone dolomitique legerement micace probablement depose dans un environnement sub-tidal. Dans la meme regi...

ABSTRACT. A new species of the arthrodire genus Groenlandaspis is described from the upper part of the Evieux Formation (Upper Famennian), based on several specimens collected from quarries at Modave and Villers-le-Temple, Liège Province, Belgium. It is the first ...

In the Sverdrup Basin (Canadian Arctic), the Lower Triassic Blind Fiord Formation, comprising siltstone and shale, overlies various Middle to Late Permian (post-Wordian) sedimentary units. This formation is subdivided into three members: the Confederation Point, Smith Creek and Svartfjeld members of, respectively, Griesbachian–Dienerian, Smithian–Spathian and Spathian ages. Lower Triassic bryozoan beds are known from many sections of Ellesmere Island, but have never been studied in detail. During the Early Triassic biotic recovery interval, immediately following the Permian/Triassic extinction event, only one new bryozoan genus evolved in the Boreal region: Arcticopora. The first lower Triassic bryozoan bed appears in the upper part of the Confederation Point Member, and is dated as late Dienerian. Succeeding bryozoan levels occur in the upper Smith Creek Member, and are late Smithian–early Spathian in age. Bryozoan beds occupy a similar stratigraphic position in Spitsbergen. There, they occur scattered in silt to coarse sandstone beds, but also in bryozoan-dominated packstone beds resembling the packstone units in the uppermost part of the Confederation Point Member of Ellesmere Island. Previously, bryozoan-rich beds of Triassic age have not been reported, and the present work fills an important time gap in the bryozoan carbonate database.