Strike-Slip Faults and Their Control on Differential Hydrocarbon Enrichment in Carbonate Karst Reservoirs: A Case Study of Yingshan Formation on Northern Slope of Tazhong Uplift,Tarim Basin

正Objective Oil and gas are abundant in the Ordovician Yingshan Formation carbonate karst reservoirs on the northern slope of Tazhong uplift in the Tarim Basin,and have extremely complicated oil-gas-water distribution,however.The     

Paleoproterozoic gabbro–diorite–granite magmatism of the Batomga Rise (NE Aldan Shield): Sm–Nd isotope geochemical evidence

The geochemical similarity and almost simultaneous (2055–2060 Ma) formation of Utakachan gabbro-amphibolite, Jagdakin granodiorite-diorite, Khoyunda granitoid, and Tygymyt leucogranite complexes, which inruded metamorphic formations of the Batomga Group are evidence of their formaton from unified magmatic source. All this makes it possibble to combine aforementioned complexes into the unified Early Proterozoic diferentiated gabbro-diorite-granite complex.     

Tychite in mantle xenoliths from kimberlites: The first find and a new genetic type

Tychite Na₆Mg₂(CO₃)₄(SO₃) is a rare natural Na and Mg sulfatocarbonate. It is found only as minor mineral in deposits of saline lakes in the United States, Canada, Uganda, and China. In these continental evaporites tychite has sedimentary genesis. In this study, we report the first occurrence of tychite as a crystal phase in the melt inclusions in olivine from mantle xenoliths of the Udachnaya-East kimberlite pipe. This find provides an evidence for the probability of tychite crystallization from melts; i.e., this rare sulfatocarbonate may have a magmatic origin as well.     

Facies analysis and sequence stratigraphy of Kometan Formation (Upper Cretaceous) in the imbricated zone,northeastern Iraq

Facies and sequence stratigraphic analysis of the Kometan Formation (Upper Cretaceous) were studied from Kometan village, Kurdistan region of northeastern Iraq. Lithologically, the formation consists of 44 m of white weathering, light grey, thin to medium-bedded highly fractured limestones with chert nodules. Petrographic study of the carbonates shows that both skeletal and non-skeletal grains were present. The skeletal grains include a variety of planktonic foraminifera (including Oligostegina), calcispheres, ostracods, pelecypods, larva ammonite, and echinoderms. Non-skeletal grains include peloids only. Three main microfacies types are distinguished in the studied formation. The results of stable carbon and oxygen isotopes of the studied carbonate samples show negative values of δ¹⁸O. These indicate that the seawater was warm with low salinity during precipitation of the carbonates in the Kometan Formation in northeastern Iraq. The positive δ¹³C values of carbonate samples, in the middle part of the formation, reflect the widespread deposition of organic-rich marine sediments during a transgression and deepening of the basin. Petrographic, facies and stable isotopic analyses revealed that the Kometan Formation was deposited in a warm, basinal, pelagic (open marine) environment with low salinity. The Kometan Formation consists of one complete third-order depositional sequence, separated by a sequence boundary (SB) of type 2. The third-order sequence is subdivided into a transgressive systems tract (TST) and highstand systems tract (HST). This reflects episodes of transgression and still stands of the relative sea level. The TSTs are topped by maximum flooding surface (MFS) characterized by deepening-/fining-upward parasequences implying a retrogradational stacking pattern. The HST is marked by shallowing-/coarsening-upward parasequences implying a progradational stacking pattern.     

Earthquake preparedness: the case of Eastern UAE

During the last 30 years, UAE witnessed earthquakes that ranged from minor to moderate, with maximum magnitude of 5.1 that occurred in the Masafi area (eastern UAE, on March 11, 2002). Recent earthquakes that hit Iran such as on May 11, 2013, caused tremors and mild shaking of buildings in some UAE cities. Although the tremors are small in magnitude, their sequences apparently become an important research topic and deserve more assessment from different perspectives such as geographical, geological, engineering, and social. This is because low risk does not equal no risk. This study is concerned with public perceptions of earthquake preparedness (reduction of disaster impact) that can be measured by various variables such as developing an emergency plan, preparation of disaster supply kits, and training. The methodology consists of a survey of 470 people who live around the Masafi area, near Fujairah city, UAE. GIS and GPS were used for site selection in conducting the survey, and remote sensing was used as an aid in identification of buildings’ ages. Results show that around 90% of the people surveyed have water tanks that can support them up to 3 days, and 60% of them normally buy food that can support them up to 2 days. Thirty percent of the respondents were familiar with storing first-aid kits and tools such as flashlights. The findings point to a need for more research regarding public awareness about earthquakes. The findings of this study may be useful for people who are involved in the four cornerstones of disaster risk reduction: community participation, public policy actions, safer construction and urban development, and development of a culture of prevention.     

Ground penetrating radar and 2D electric resistivity studies for tracing hydrocarbon leakage site,close to Abha City: a case study

This work presents the application of the ground-penetrating radar (GPR) method and electric resistivity tomography (ERT) technique in outlining a zone of contamination due to the light non-aqueous phase liquid (LNAPL) plume underground in the area of an impacted fuel station, close to Abha City. The GPR has been performed using SIR3000 unit with the 100 and 400 MHz antennas. The main objective of the GPR survey was to evaluate the lateral extension of contamination. The complex GPR signature of the plume was well characterized. Low reflectivity zone corresponds to hydrocarbon vapor phase in the vadose zone. Enhanced reflections are associated with free and residual products in the fractured saturated zone directly above the water table. An electric resistivity tomography (ERT) survey was performed on four profiles within the site to investigate the vertical and horizontal extent of the contamination plume and to define the bottom of the landfill. The 2D electric profiles show the presence of low-resistivity (4O to 37 Ω m) anomalies that refers to the presence of accumulated hydrocarbons. From the interpretation of the GPR and ERT profile, it was possible to locate the top and bottom of the contamination plume of the waste disposal site. The radar signal penetrated deep enough and enabled the identification of a second reflector at approximately 10-m deep, interpreted as the hard basement surface which causes the strong amplitude reflection in the GPR profile. The results of GPR and ERT showed good agreement.     

Causes of the great mass extinction of marine organisms in the Late Devonian

The second of the five great mass extinctions of the Phanerozoic occurred in the Late Devonian. The number of species decreased by 70–82%. Major crises occurred at the Frasnian–Famennian and Devonian–Carboniferous boundary. The lithological and geochemical compositions of sediments, volcanic deposits, impactites, carbon and oxygen isotope ratios, evidence of climate variability, and sea level changes reflect the processes that led the critical conditions. Critical intervals are marked by layers of black shales, which were deposited in euxinic or anoxic environments. These conditions were the main direct causes of the extinctions. The Late Devonian mass extinction was determined by a combination of impact events and extensive volcanism. They produced similar effects: emissions of harmful chemical compounds and aerosols to cause greenhouse warming; darkening of the atmosphere, which prevented photosynthesis; and stagnation of oceans and development of anoxia. Food chains collapsed and biological productivity decreased. As a result, all vital processes were disturbed and a large portion of the biota became extinct.     

Main results of recent investigations into the physical mechanisms of the interaction of tropical cyclones and the ionosphere

Izvestiya, Atmospheric and Oceanic Physics - International investigations into the correlation between tropical cyclones (TCs) and the ionosphere are associated with great difficulties in proving...     

Cycles of seismic activity in the second half of the holocene in the Western Caucasus and their correlation with stages of civilization development: A case study of the upper reach of the Mzymta River

The results of comprehensive research into the area of the upper reach of the Mzymta River (Western Caucasus) are presented. The evidence of strong earthquakes that struck the study area throughout history is studied. The periods when mud flows and rockslides associated with the earthquakes are identified to fall between 3100–4000 and 700–1200 years ago. Paleoseismological results are correlated to the results of archeological excavations. As a result, it is revealed that the periods of tectonic disasters coincided with the onsets of the period when the area was uninhabited (abandoned) by people. The results of the present comprehensive research provide additional information to specify the seismic hazard and the chronology of human habitation in the region.