Geology of the Hebridean margin of the Rockall Trough

1986 ◽  
Vol 88 ◽  
pp. 27-51 ◽  
Author(s):  
E. J. W. Jones ◽  
R. G. Perry ◽  
J. L. Wild
Keyword(s):  
Large Scale ◽  
Sediment Accumulation ◽  
Geological Structure ◽  
Volcanic Material ◽  
Surface Ship ◽  
Rockall Trough ◽  
Outer Hebrides ◽  
Basic Volcanic ◽  
Cenozoic Sediments ◽  
Early Cenozoic

SynopsisThe geological structure and history of the Rockall Trough margin to the west of the Outer Hebrides (57°N-59°N) has been inferred from the analysis of bottom samples, seismic, sonar, magnetic, satellite altimeter and surface-ship gravity observations. Much of the continental shelf consists of a shallow platform of Precambrian Lewisian basement, covered by a thin (<300m) blanket of Cenozoic sediments. Apart from areas near the shelf break and immediately west of Lewis, the basement has not undergone the large-scale subsidence typical of many regions adjacent to the Rockall Trough. Beneath the outer shelf, the Lewisian dips steeply towards the deeper water and is covered by a westwardthickening succession (>3km) of Mesozoic and Cenozoic sediments.The eastern margin of the Rockall Trough appears to have been well established as a site of deposition by the end of the Triassic. Further subsidence occurred during the late Jurassic and continued into the Cretaceous when the axial province of the Rockall Trough off the Hebrides was invaded by basic volcanic material. Subsequently, the region was profoundly affected by early Cenozoic igneous activity. The long-term buoyancy of the Lewisian basement under the Outer Hebridean platform and early-formed structural discontinuities within it have influenced the overall pattern of sediment accumulation and the distribution of volcanic activity along the margin. During the later stages of deposition, sedimentation was closely controlled by the presence of early Cenozoic volcanics, by bottom currents and by glacial processes.

Mechanics Research on Rock Stress and Deformation of Lancang River Canyon's Large - Scale Dumping Deformation

2013 ◽  
Vol 353-356 ◽  
pp. 318-323
Author(s):  
Song Ye ◽  
Yu Sheng Li ◽  
Qian Guo
Keyword(s):  
Large Scale ◽  
Geological Structure ◽  
Deformation Characteristics ◽  
Deep Part ◽  
Trailing Edge ◽  
Geological Surveys ◽  
Depth Analysis ◽  
Numerical Simulation Methods ◽  
Complex Geological Structure ◽  
Stress And Deformation

This article is based on geological surveys combined with finite element and discrete element numerical simulation methods. In-depth analysis of the complex geological structure, deformation characteristics and stress - deformation problems of dumping rock, we clarify different deformation characteristics of deformable landslide inside, at the bottom and the deep part of trailing edge, and demonstrate the deformation will gradually shift from dumping to shear slip. Potential deformation failure mode will be dumped into the whole sliding - tension, which is controlled by the bottom broken belt, and potential deformation is mainly subject to the bottom fault F207-3 of deformed rock and the dumping broken belt at the deep part of trailing edge.

scholarly journals Features of the geological structure, tectonic development and oil and gas potential of the Chezhen depression (Bohai bay basin)

2021 ◽  
Vol 63 (5) ◽  
pp. 8-16
Author(s):  
Sh. Qiu ◽  
N. A. Kasyanova
Keyword(s):  
Large Scale ◽  
Oil And Gas ◽  
Geological Structure ◽  
Fault System ◽  
Bohai Bay ◽  
Industrial Oil ◽  
Tectonic Development ◽  
Geophysical Information ◽  
Oil Deposits ◽  
Gas Potential

Background. In terms of oil and gas, the territory of the Chezhen depression has been studied insufficiently compared to the neighbouring same-range depressions. These depressions complicate the first-order Jiyang depression, geographically coinciding with the largest Shengli hydrocarbon field. In recent years, much geological and geophysical information about the oil geologyof the Chezhen depression has been accumulated, which allows its prospecting oil and gas potential to be assessed.Aim. To reveal regular features of the geological structure and location of oil deposits in the Chezhen depression in order to support the prospecting and exploration work within the Chezhen block of the Shengli field.Materials and methods. A comprehensive analysis of literature data and collected materials was conducted. A historical and geodynamic study of the evolution of the studied area according to literature data was carried out, along with an analysis of the most recent geological and geophysical information and exploration data based on the materials of the “Shengli AKOO Sinopek” oil company. The analysis was based on the data from 52 drilling wells and the results of seismic surveys performed in the central part of the Chezhen depression.Results. Specific features of the block geological structure of the area under study were established, which formed under the repeated influence of large-scale horizontal tectonic movements occurring at different periods of geological history. The role of the most recent fault system in the modern spatial distribution of oil deposits was determined.Conclusions. Our studies demonstrate a great prospecting potential of the Chezhen depression territory, where the discovery of new industrial oil deposits can be expected.

scholarly journals Effects of Formation Dip on Gas Production from Unconfined Marine Hydrate-Bearing Sediments through Depressurization

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yilong Yuan ◽  
Tianfu Xu ◽  
Yingli Xia ◽  
Xin Xin
Keyword(s):  
Large Scale ◽  
Horizontal Well ◽  
Field Measurements ◽  
Production Method ◽  
Geological Structure ◽  
Horizontal Distribution ◽  
Gas Production ◽  
Well Completion ◽  
Hydrate Reservoir ◽  
Hydrate Bearing Sediments

The effects of geologic conditions and production methods on gas production from hydrate-bearing sediments (HBS) have been widely investigated. The reservoir was usually treated as horizontal distribution, whereas the sloping reservoir was not considered. In fact, most strata have gradients because of the effects of geological structure and diagenesis. In this study, based on currently available geological data from field measurements in Shenhu area of the South China Sea, the effects of formation dip on gas production were investigated through depressurization using a horizontal well. The modeling results indicate that the strategy of horizontal well is an effective production method from the unconfined Class 2 HBS. The predicted cumulative volume of methane produced at the 1000 m horizontal well was 4.51 × 107 ST m3 over 5-year period. The hydrate dissociation behavior of sloping formation is sensitive to changes in the reservoir pressure. As in unconfined marine hydrate reservoir, the sloping formation is not conducive to free methane gas recovery, which results in more dissolved methane produced at the horizontal well. The obvious issue for this challenging target is relatively low exploitation efficiency of methane because of the recovery of very large volumes of water. Consequently, the development of the favorable well completion method to prevent water production is significantly important for realizing large scale hydrate exploitation in the future.

Conceptual Design of the Flow Noise Simulator

2003 ◽  
Author(s):  
Ryuichi Sato ◽  
Takayuki Mori ◽  
Ryo Yakushiji ◽  
Kenji Naganuma ◽  
Masaharu Nishimura ◽  
...  
Keyword(s):  
Conceptual Design ◽  
Large Scale ◽  
Scale Model ◽  
Variable Pressure ◽  
Cavitation Noise ◽  
Flow Noise ◽  
Model Studies ◽  
Surface Ship ◽  
Noise Measurements ◽  
Under Construction

The Flow Noise Simulator (FNS) of the 1st Research Center of TRDI/JDA (Japan Defense Agency) is a large, variable pressure, recirculating water tunnel with very low background noise level. The tunnel is 20m high and 49m long, containing 2000m3 of water. The test section has a square cross section of 2m × 2m with 10m in length. It will accept large size surface ship models of 6m, submarine models of 4m in length and full scale ship appendix models. The FNS is currently under construction and will be accomplished in 2005. It will be used for a wide variety of hydrodynamic and hydroacoustic testing of surface ships and submarines, such as propeller cavitation noise measurements and propeller-hull interaction observation, with sufficiently large scale models. Conceptual design of the FNS was started in 1996 and evaluated by following scale model studies. This paper discusses some technical issues of the FNS.

Global wind-induced change of deep-sea sediment budgets, new ocean production and CO 2 reservoirs ca . 3.3-2.35 Ma BP

1988 ◽  
Vol 318 (1191) ◽  
pp. 487-504 ◽  
Keyword(s):  
Large Scale ◽  
Accumulation Rate ◽  
Sediment Accumulation ◽  
Distribution Patterns ◽  
Trade Wind ◽  
Accumulation Rates ◽  
Deep Sea Sediment ◽  
Late Pliocene ◽  
High Productivity ◽  
Sediment Fraction

The late Pliocene phase of large-scale climatic deterioration about 3.2-2.4 Ma BP is well documented in a number of (benthic) δ 18 O records. To test the global implications of this event, we have mapped the distribution patterns of various sediment variables in the Pacific and Atlantic Oceans during two time slices, 3.4-3.18 and 2.43-2.33 Ma BP. The changes of bulk sedimentation and bulk sediment accumulation rates are largely explained by the variations of CaCO 3 -accumulation rates (and the accumulation rates of the complementary siliciclastic sediment fraction near continents in higher latitudes). During the late Pliocene, the CaCO 3 -accumulation rate increased along the equatorial Pacific and Atlantic and in the northeastern Atlantic, but decreased elsewhere. The accumulation rate of organic carbon (C org ) and net palaeoproductivity also increased below the high-productivity belts along the equator and the eastern continental margins. From these patterns we may conclude that (trade-) wind- induced upwelling zones and upwelling productivity were much enhanced during that time. This change led to an increased transfer of CO 2 from the surface ocean to the ocean deep water and to a reduction of evaporation, which resulted in an aridification of the Saharan desert belt as depicted in the dust sediments off northwest Africa.

scholarly journals Measurement and simulation of the 16/17 April 2010 Eyjafjallajökull volcanic ash layer dispersion in the northern Alpine region

2011 ◽  
Vol 11 (6) ◽  
pp. 2689-2701 ◽  
Author(s):  
S. Emeis ◽  
R. Forkel ◽  
W. Junkermann ◽  
K. Schäfer ◽  
H. Flentje ◽  
...  
Keyword(s):  
Spatial Structure ◽  
Numerical Simulations ◽  
Large Scale ◽  
Scale Model ◽  
Network Data ◽  
Aerosol Layer ◽  
Volcanic Origin ◽  
Southern Germany ◽  
Volcanic Material ◽  
Ash Layer

Abstract. The spatial structure and the progression speed of the first ash layer from the Icelandic Eyjafjallajökull volcano which reached Germany on 16/17 April is investigated from remote sensing data and numerical simulations. The ceilometer network of the German Meteorological Service was able to follow the progression of the ash layer over the whole of Germany. This first ash layer turned out to be a rather shallow layer of only several hundreds of metres thickness which was oriented slantwise in the middle troposphere and which was brought downward by large-scale sinking motion over Southern Germany and the Alps. Special Raman lidar measurements, trajectory analyses and in-situ observations from mountain observatories helped to confirm the volcanic origin of the detected aerosol layer. Ultralight aircraft measurements permitted the detection of the arrival of a second major flush of volcanic material in Southern Germany. Numerical simulations with the Eulerian meso-scale model MCCM were able to reproduce the temporal and spatial structure of the ash layer. Comparisons of the model results with the ceilometer network data on 17 April and with the ultralight aircraft data on 19 April were satisfying. This is the first example of a model validation study from this ceilometer network data.

scholarly journals GEOLOGY AND PETROGRAPHY OF THE VEDEL ISLANDS (WILHELM ARCHIPELAGO, WEST ANTARCTICA)

2020 ◽  
pp. 18-27
Author(s):  
O. Mytrokhyn ◽  
V. Bakhmuto
Keyword(s):  
Large Scale ◽  
Deep Level ◽  
Geological Structure ◽  
Geological Mapping ◽  
Small Island ◽  
West Antarctica ◽  
Mode Of Occurrence ◽  
Plutonic Rocks ◽  
The Antarctic ◽  
Tectonic Exhumation

The Vedel Islands are a small island group that is part of the Wilhelm archipelago in the West Antarctica. They are located near the Graham Coast of the Antarctic Peninsula at a distance of 12 km from Akademik Vernadsky Ukrainian Antarctic Station. Until recently, the Vedel Islands were a "white spot" on all existing geological maps. In 2019, during the seasonal work of the 24th Ukrainian Antarctic expedition, the authors first carried out field geological researches on the Vedel Islands. The main goal of the geological survey was reconnaissance and large-scale geological mapping. The general ideas about the geological structure of the study area were developed by further processing of the collected materials. The preliminary data about the mode of occurrence, the geological ages, the petrographic peculiarities and the ore potential of the local rocks were also obtained. It was first established that multiple-aged intrusive-magmatic formations take part in the geological structure of the Vedel Islands. The intermediate compositions of the plutonic rocks namely the diorites and quartz diorites are the most common among them. The gabbroids and the tonalites are less common. The least common ones are hypabyssal and subvolcanic dike rocks namely microdiorites and diabases. The plutonic rocks were formed in at least three intrusive phases with a homodromous order of their intrusions. The most ancient among them are gabbroids. The Early Cretaceous age for their formation is assumed by analogy with the petrographically similar rocks of the Tuxen-Rasmussen layered gabbroid intrusion (TRGI). The tonilites are the youngest plutonic rocks on the Vedel Islands. It is assumed that their formation at a deep level took place in the Late Cretaceous, although their tectonic exhumation and the final erosion outcropping occurred in the Paleogene and ended in the Neogene. In the process of the exhumation, the plutonic rocks were intruded by hypabyssal dikes of microdiorites. The youngest subvolcanic diabase dykes intruded the tonalites supposedly after their complete erosion outcropping i. e. in Neogene or even Quaternary. Like TRGI and other layered gabbroid intrusions of the Wilhelm archipelago, the Vedel island gabbroids contain iron-titanium oxide-ore and copper-silicate mineralization, which requires further study. The additional researches are also needed to clarify the age, origin, petrography and mineralogy of the numerous veins of aplite-pegmatoid granite which intrude gabbroids and diorites on the Vedel Islands.

scholarly journals A Geological-Geophysical Prospecting Model for Deep-Seated Gold Deposits in the Jiaodong Peninsula, China

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1393
Author(s):  
Mingchun Song ◽  
Guoqiang Xue ◽  
Hongbo Liu ◽  
Yixin Li ◽  
Chunyan He ◽  
...  
Keyword(s):  
Large Scale ◽  
Fault Location ◽  
Geophysical Methods ◽  
Mining Area ◽  
Geological Structure ◽  
Gold Deposits ◽  
Geophysical Prospecting ◽  
Metallogenic Model ◽  
Jiaodong Peninsula ◽  
Frequency Domain Methods

The North China Craton is one of China’s major gold-producing areas. Breakthroughs have been continually made in deep prospecting at depths of 500–2000 m in the Jiaodong Peninsula, and geophysical methods have played an important role. Given that the geophysical signals of deep-seated gold deposits are difficult to detect, due to their thick overburden layers, conventional geophysical methods are not suitable for deep prospecting. Therefore, this study upgrades the geological-geophysical prospecting model, which is based on the deep metallogenic model and geophysical method of large exploration depths. Based on the analysis of the metallogenic geological factors of the altered-rock-type gold deposits in the fracture zones of the Jiaodong Peninsula, this study proposes that the gold deposits are controlled by large-scale faults, generally occur near the contact interfaces between the Early Precambrian metamorphic rock series and Mesozoic granitoids, and exhibit a stepped metallogenic model. This model then becomes the prerequisite and basic condition for deep prospecting by geophysical methods. For this reason, the traditional geophysical model, which focuses on the exploration of shallow mineralization anomalies, is transformed into a comprehensive multi-parameter geological-geophysical qualitative prospecting model highlighting the exploration of ore-controlling structural planes. The model adopts various frequency domain methods (e.g., CSAMT, AMT, WFEM), reflection seismology, and other methods to detect the deep geological structure. The characteristics of parameters such as gravity and magnetism, resistivity, polarizability, and the seismic reflection spectrum are applied to identify the ore-controlling fault location and dip angle change, and to estimate the ore-bearing location according to the stepped metallogenic model. The prospecting demonstration of deep-seated gold deposits in the Shuiwangzhuang mining area indicates the effectiveness of the comprehensive model. The comprehensive deep prospecting model effectively solves the problem of deep prospecting of gold deposits controlled by faults, promotes the great breakthrough of deep prospecting in the Jiaodong Peninsula, and provides an important technology demonstration for deep prospecting throughout China.

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