Novel Viral Communities Potentially Assisting in Carbon, Nitrogen, and Sulfur Metabolism in the Upper Slope Sediments of Mariana Trench

The Mariana Trench harbors a substantial number of infective viral particles. However, very little is known about the identity, survival strategy, and potential functions of viruses in the trench sediments.

Marine Geology of the Turnagain Area

<p>The Turnagain Area covers the continental shelf and slope off the east coast of North Island, New Zealand between Napier and Castlepoint. Its late Quaternary stratigraphy, tectonic history, sedimentation and foraminiferal distribution are described with the aid of continuous seismic profiles, sediment samples and cores. Results are presented in seven papers and a chart. The first three papers deal mainly with sub-bottom layers revealed by continuous seismic profiles; the next three papers describe dried sediment samples and cores and the last paper is a study of foraminifera in alcohol-preserved sediment samples. The topics discussed in each of the seven papers are as follows: 1. stratigraphy, sedimentation rates and origin of present topography on the continental shelf and upper slope; 2. rates of tectonic processes; 3. slumping; 4. distribution of sediments; 5. ages of indurated sediments; 6. ash horizons and rates of deposition on the lower part of the continental slope. 7. the distribution of living and dead foraminifera. The chart shows bathymetry and nature of sediment at the seabed. The sediments beneath the sea have been folding since Miocene times in the same way as marine sediments on the adjacent land. On the seabed anticlinal crests are preserved as ridges and banks and synclines form depressions. The present land area is rising and much of the seabed is sinking; the zero isobase between then is situated on the inner continental shelf. It has been at about the same position throughout Late Quaternary times, being always close to the dividing line between net erosion and net deposition. Rates of tilting have ranged from 2 to 36 microdegrees/thousand years and rates of vertical movement from +1.7 to -1.5 m/thousand years. Seaward of the zero isobase the continental shelf and upper slope has been built upwards and outwards by prisms of sediment, each prism representing a phase either of low sea level or of high sea level. Prisms deposited during periods of glacially lowered sea level are at their thickest beneath the upper slope; prisms deposited during periods of relatively high sea level are at their thickest beneath the continental shelf. Parts of the youngest prism on the upper slope have slumped on gradients as low as 1 [degree]. The topography and sediments formed during the last 20 thousand years have received the most attention. The present continental shelf if a composite feature. The inner part has been formed by wave-planation of hard rock near shore and deposition of the latest prism of sediment offshore. The outer part and the shelf break were formed by wave-planation and by deposition during the last low sea level about 20 thousand years ago. At that time the shelf break ranged in depth from about 40m to about 70m, being shallowest where eroded into soft sediment and deepest where deposited beyond the seaward edge of erosion. In adjacent areas the shelf break was probably formed at depths of less than 20m being eroded into hard rock. The inner part of the wave-planed surface formed at that time is now deeply buried by the latest prism of sediment but the outer part is covered by only a thin veneer. The outer shelf is still essentially a drowned low sea level feature. At the thickest part of the prism on the mid continental shelf, rates of deposition above an 8 thousand year old seismic reflector range from about 1 to about 4 m/thousand years, being most rapid south of major rivers. Rates are too slow to be measured at some places near the shelf break and at ridges on the continental slope. In depressions on the continental slope, sedimentation rates are indicated by the depth of the 3.4 thousand year old Waimihia ash and range from 0.36 m/thousand years in a depression relatively near land to 0.02 m/thousand years in the depression furthest from land. Sediments range from fine sand near shore to clayey fine silt on the lower slope. Many sediments are bimodal because they were deposited as a mixture of floculated and unfloculated grains. Rapidly deposited sediment on the continental shelf is predominantly detrital sand and silt; slowly deposited sediment near the shelf break and on ridges consists mostly of volcanic ash, foraminifera, and glauconite Muddy sediment in continental slope depressions contains sandy turbidite layers. Different environments are characterised by sediment types and foraminiferal faunas that can be matched in Tertiary Rocks.</p>

Marine Geology of the Turnagain Area

<p>The Turnagain Area covers the continental shelf and slope off the east coast of North Island, New Zealand between Napier and Castlepoint. Its late Quaternary stratigraphy, tectonic history, sedimentation and foraminiferal distribution are described with the aid of continuous seismic profiles, sediment samples and cores. Results are presented in seven papers and a chart. The first three papers deal mainly with sub-bottom layers revealed by continuous seismic profiles; the next three papers describe dried sediment samples and cores and the last paper is a study of foraminifera in alcohol-preserved sediment samples. The topics discussed in each of the seven papers are as follows: 1. stratigraphy, sedimentation rates and origin of present topography on the continental shelf and upper slope; 2. rates of tectonic processes; 3. slumping; 4. distribution of sediments; 5. ages of indurated sediments; 6. ash horizons and rates of deposition on the lower part of the continental slope. 7. the distribution of living and dead foraminifera. The chart shows bathymetry and nature of sediment at the seabed. The sediments beneath the sea have been folding since Miocene times in the same way as marine sediments on the adjacent land. On the seabed anticlinal crests are preserved as ridges and banks and synclines form depressions. The present land area is rising and much of the seabed is sinking; the zero isobase between then is situated on the inner continental shelf. It has been at about the same position throughout Late Quaternary times, being always close to the dividing line between net erosion and net deposition. Rates of tilting have ranged from 2 to 36 microdegrees/thousand years and rates of vertical movement from +1.7 to -1.5 m/thousand years. Seaward of the zero isobase the continental shelf and upper slope has been built upwards and outwards by prisms of sediment, each prism representing a phase either of low sea level or of high sea level. Prisms deposited during periods of glacially lowered sea level are at their thickest beneath the upper slope; prisms deposited during periods of relatively high sea level are at their thickest beneath the continental shelf. Parts of the youngest prism on the upper slope have slumped on gradients as low as 1 [degree]. The topography and sediments formed during the last 20 thousand years have received the most attention. The present continental shelf if a composite feature. The inner part has been formed by wave-planation of hard rock near shore and deposition of the latest prism of sediment offshore. The outer part and the shelf break were formed by wave-planation and by deposition during the last low sea level about 20 thousand years ago. At that time the shelf break ranged in depth from about 40m to about 70m, being shallowest where eroded into soft sediment and deepest where deposited beyond the seaward edge of erosion. In adjacent areas the shelf break was probably formed at depths of less than 20m being eroded into hard rock. The inner part of the wave-planed surface formed at that time is now deeply buried by the latest prism of sediment but the outer part is covered by only a thin veneer. The outer shelf is still essentially a drowned low sea level feature. At the thickest part of the prism on the mid continental shelf, rates of deposition above an 8 thousand year old seismic reflector range from about 1 to about 4 m/thousand years, being most rapid south of major rivers. Rates are too slow to be measured at some places near the shelf break and at ridges on the continental slope. In depressions on the continental slope, sedimentation rates are indicated by the depth of the 3.4 thousand year old Waimihia ash and range from 0.36 m/thousand years in a depression relatively near land to 0.02 m/thousand years in the depression furthest from land. Sediments range from fine sand near shore to clayey fine silt on the lower slope. Many sediments are bimodal because they were deposited as a mixture of floculated and unfloculated grains. Rapidly deposited sediment on the continental shelf is predominantly detrital sand and silt; slowly deposited sediment near the shelf break and on ridges consists mostly of volcanic ash, foraminifera, and glauconite Muddy sediment in continental slope depressions contains sandy turbidite layers. Different environments are characterised by sediment types and foraminiferal faunas that can be matched in Tertiary Rocks.</p>

Kutei Basin oil bearing sand reservoirs mapping using integrated seismic methods

The Lower Kutei Basin which contains several giant oil and gas fields is located on the East Kalimantan, Indonesia. This paper discusses the identification and mapping of oil-filled reservoirs and their depositional facies by integrating seismic stratigraphy, attributes, and AI (Acoustic Impedance) inversion methods. The log data cross-plots show that AI can be used to distinguish oil-sands from wet sands and shale, and to derive the total porosity of the sands. However, AI and amplitude values are greatly affected by the oil, porosity and tuning effects, hence they cannot be used to identify the facies containing the oil-bearing sands. Therefore, to map the facies containing the oil-filled sands, the AI map is combined with the variance and sweetness maps. It can be seen clearly from the variance and sweetness maps that the oil-sands suggested by the AI map are contained in a narrow and elongate meander-like geometry which is typical of channel facies. The variance and sweetness maps suggest that there are two channels in the study area. To determine which channel is thicker, spectral decomposition RGB map was made. The result suggests that the right channel is more prospective as it associates with thicker sand deposits. The combination of variance, sweetness and RGB maps strongly indicate that the channels in the study area are in upper-slope environment, and the thicker oil-sands are located in the eastward of the study area.

Records of plutonium isotopes in marine sediments from the southern Gulf of Mexico

Here we report on new data on plutonium (Pu) isotopes to elucidate activity concentrations, inventories, sources and their transport from the ocean surface to the sea floor from a collection of deep-sea sediment cores (depths ranging from 257 to 3739 m) in the Gulf of Mexico (GoM). Sediment cores collected from the continental shelf and upper slope region of the GoM consistently showed 240Pu/239Pu ratios of 0.15 to 0.26 and Pu-inventories ranging from 15 to 35 Bq m− 2. Inventories and ratios are consistent with global fallout Pu for this tropical region. In the continental shelf and upper slope regions, higher particle concentrations close to the margins favor significant scavenging and removal of Pu from the water column; in contrast with the deep-sea cores that show low 240Pu/239Pu ratios (0.07–0.13) and a much lower Pu inventory (< 7 Bq m-2) implying a small fraction of the expected global fallout inventory has reached into the lower slopes and abyssal plain of the GoM. Low values and a progressive decrease of 240Pu/239Pu ratios and Pu inventories with increasing water depth have been previously reported for the GoM. The low Pu ratios indicate that Nevada tests fallout was an important source of Pu to deep-sea sediments, and that this source was likely more efficiently removed from the water column than global fallout Pu. Analysis of Pu isotopes in two sediment traps from the upper slope regions show 240Pu/239Pu ratios comparable to the ones observed in the global fallout. These results indicate that global fallout Pu is currently the main source of Pu in water column particles. Therefore, a significant fraction of global fallout Pu must still be present; either in a dissolved phase, or as biologically recycled material in the water column, or scavenged on the shelf and shelf break. Our results bring to light important questions on the application of Pu isotopes to establish sediment chronologies, since these radionuclides are shown to be tracers of bioturbation rather than accumulation processes in deep-sea sediments of the GoM, similar to previously reported results from excess 210Pb.

Soil Properties and Growth of Maize as Affected by Slope Position and Fertilizer Type on Coastal Plain Sands

A study was conducted to determine the effects of slope position and fertilizer type on soil properties and growth of maize (Zea mays) on Coastal Plain Sands of Akwa Ibom State, Nigeria. Results obtained showed that soils of lower slope (LS) had the highest contents of clay and silt compared with those of upper slope (US) position. Bulk density of the upper slope soil and that of the middle slope (MS) soils were significantly higher (P≤0.05) than that of LS soil and subsequently, total porosity and saturated hydraulic conductivity (Ksat) increased downslope. Bulk density of soils that received poultry manure (PM) and NPK+PM were significantly reduced compared to those of NPK and control while total porosity and Ksat of soils that received PM and NPK+PM were significantly higher (P≤0.05) than those of NPK and control. Soils of LS had highest pH, organic carbon, total nitrogen, available phosphorus, ECEC compared to those of MS and US. The application of poultry manure yielded increase in soil pH, soil organic carbon, total nitrogen, available phosphorus and ECEC when compared to soils of NPK and control. Growth of maize obtained with LS were consistently higher than those of the MS and US soils. Soils of LS that received NPK and NPK+PM had consistently similar maize growth, higher than other combinations of slope position and fertilizer type. The complementary application of poultry manure and NPK 15:15:15 can be the best option for increasing the fertility of soils with varying slope positions on Coastal Plain Sands.

Reconstruction of the Upper Slope Conditions of an Extraordinary Hydro-Meteorological Event Along the Jamapa Glacier Drainage System, Citlaltépetl (Pico de Orizaba) Volcano, Mexico

A singular precipitation event on the summit glacial slopes of Mexico’s highest volcanic peak, Citlatépetl (also known as Pico de Orizaba), associated with the passage of Hurricane Ernesto across the southern Mexico mainland in August 2012, resulted in a debris flow at altitudes above 4,400 m asl, culminating in a hyperconcentrated flow downstream that had major impacts to a river valley’s channel morphology as well as to communities along a 25 km runout. The lahar originated at the terminal moraine and proglacial ramp of the Little Ice Age (LIA) extent of Citlaltépetl’s Jamapa glacier. Precipitation amounts were estimated based on nearby CONAGUA stations, but also on TRMM satellite images leading to an estimated 106 mm for a 3 day total, with 85 mm (80% of the total) falling on August 9th, the date when the lahar event occurred. The initial debris flow removed a minimum estimated 60,000 m3 of material from the proglacial ramp. A possible causative scenario is that the precipitation event overpressured the groundwater hydrology of an already unstable glacial-melt-saturated moraine. We demonstrate a methodology for the recreation of a pre-event landscape and the environmental conditions at the onset of the lahar, utilizing satellite products, in-situ geomorphological and geological evidence, and UAS technology.

Calculation Method of Fastening the Upper Slope of the Land Bund for Erosion and Strength

To protect the slopes of the ground dam from the devastating effects of wind waves, ice, water flow, precipitation and other factors, a number of engineering measures are provided. Based on this, an engineering decision is taken on the choice of materials for fastening structures, as well as methods for calculating their stability. When calculating the stability of the upper slope, two cases of a combination of loads and impacts are mainly considered. One of them is the reduction of the water level in the reservoir with maximum speed, and the other is the case when the water level in the reservoir is at the lowest operational level. The article investigates the processes of sliding of natural slopes of the upstream dam. Taking into account the combined action of the forces of filtering, weighing and vapor pressure, as well as the force of hydrostatic pressure to the level of dead volume. The equation for the stability coefficient of a circular-cylindrical slip of a uniform natural slope of the upstream dam has been obtained.

Progradational slope architecture and sediment distribution in outcrops of the mixed carbonate-siliciclastic Bone Spring Formation, Permian Basin, west Texas

Sediment transport and distribution are the keys to understanding slope-building processes in mixed carbonate-siliciclastic sediment routing systems. The Permian Bone Spring Formation, Delaware Basin, west Texas, is such a mixed system and has been extensively studied in its distal (basinal) extent but is poorly constrained in its proximal upper-slope segment. Here, we define the stratigraphic architecture of proximal outcrops in Guadalupe Mountains National Park in order to delineate the shelf-slope dynamics of carbonate and siliciclastic sediment distribution and delivery to the basin. Upper-slope deposits are predominantly fine-grained carbonate lithologies, interbedded at various scales with terrigenous (i.e., siliciclastic and clay) hemipelagic and gravity-flow deposits. We identify ten slope-building clinothems varying from terrigenous-rich to carbonate-rich and truncated by slope detachment surfaces that record large-scale mass wasting of the shelf margin. X-ray fluorescence (XRF) data indicate that slope detachment surfaces contain elevated proportions of terrigenous sediment, suggesting that failure is triggered by changes in accommodation or sediment supply at the shelf margin. A well-exposed terrigenous-rich clinothem, identified here as the 1st Bone Spring Sand, provides evidence that carbonate and terrigenous sediments were deposited contemporaneously, suggesting that both autogenic and allogenic processes influenced sediment accumulation. The mixing of lithologies at multiple scales and the prevalence of mass wasting acted as primary controls on the stacking patterns of terrigenous and carbonate lithologies of the Bone Spring Formation, not only on the shelf margin and upper slope, but also in the distal, basinal deposits of the Delaware Basin.