30 research outputs found
Understanding the origin of Cambrian marine oncoids: A petrologic, geochemical, and isotopic perspective
No full textTracing the geochemical imprints of Maastrichtian black shales in southern Tethys, Egypt: Assessing hydrocarbon source potential and environmental signatures
No full textEffect of Depositional Environment and Climate on Organic Matter Enrichment in Sediments of the Upper Miocene—Pliocene Kampungbaru Formation, Lower Kutai Basin, Indonesia
No full textThe Upper Miocene–Pliocene Kampungbaru Formation crops out in the easternmost part of the Lower Kutai Basin, Indonesia. The sedimentological analysis of seven outcrops was carried out, and a total of twenty-five samples from these outcrops was analyzed for bulk geochemistry, organic petrography, and bulk and clay mineralogy to assess the effect of the climate and depositional environment on organic matter enrichment. The Kampungbaru Formation consists of interbedded sandstone, siltstone, claystone, and thick coal beds, which were classified into eleven lithofacies. Subsequently, seven facies associations were identified, namely the fluvial-dominated distributary channel, sheet-like sandstone, tide-influenced distributary channel, mouth bar, crevasse splay, delta plain, and delta front. The coal facies generally have a high amount of total organic carbon (TOC, 5.1–16.9; avg. 10.11 wt.%), and non-coal layers range from 0.03 to 4.22 wt.% (avg. 1.54 wt.%). The dominant maceral is vitrinite, while liptinite occurs only rarely in the samples. Organic matter is inferred to have originated from terrestrial plants growing in mangrove swamps. Identified clay minerals include varying proportions of kaolinite, illite, chlorite, and mixed layer illite/smectite (I/S). Kaolinite, which commonly constitutes up to 30% of the clay volume, indicates intensive chemical weathering during a warm and humid climate. In accordance with the Köppen climate classification, the paleoclimate during the deposition of the Kampungbaru Formation is classified as type Af, which is a tropical rainforest. Tropical climate was favorable for the growth of higher plants and deposition of organic matter under anoxic conditions and led to higher amounts of TOC in the Kampungbaru Formation
Provenance Characterization of Campanian Lacustrine Organic-Rich Mudstones on the Southern Tethyan Margin, Egypt
No full textStudy of Immunoglobulin G Avidity to Herpes simplex 2 in Pregnant Egyptian Women: One Center Report
No full textBackground: Herpes simplex virus is a DNA virus. It has two types herpes simplex 1 and herpes simplex 2. Affection of pregnant women by this virus carries adverse effect to the pregnancy outcomes.Aim: The aims of the current study were to determine the HSV-2 seroprevalence associated with infection among a sample of Egyptian pregnant women, and also IgG avidity index was evaluated to detect early HSV-2 infections. Moreover, polymerase chain reaction was used to identify the presence of viremia among seropositive screened women.Material and Method: The study included 186 pregnant women in the third trimester. Blood samples were obtained for serological studies of herpes simplex 2 (HSV2) by immunoglobulin G (IgG) and immunoglobulin M (IgM) and IgG avidity test. Molecular study of HSV2 virus DNA in blood samples by polymerase chain reaction (PCR).Results: For virological markers for HSV2, the most common marker was positive IgG 26.9%, followed by PCR for HSV2 DNA15.6% and IgM 14%%.None of the patients had any other positive markers for Toxoplasma, rubella or CMV. Study of the avidity index for HSV2 IgG revealed that IgG index was <67% in 30 positive samples (60%) while 20 (40%) samples had an avidity index >67%. In women with bad obstetric history, the most common HSV2 marker was IgG (50%) followed by PCR (30.8%) and IgM. IgG validity index indicating recent infection, i.e. <67% were found in 21.8%. The virological markers for HSV2 were statistically significantly higher in women with BOH compared with women with a normal pregnancy history (P=0. 0001). There was statistically significant correlations between positive PCR results and IgM (65.5%, P=0. 0001), IgG (79.3%- P=0. 0001) and IgG index <67% (48.3%- P=0. 0001).Conclusion: The study highlights that of herpes simplex virus 2 is mundane among pregnant Egyptian women. Avidity test for IgG is valuable for laboratory diagnosis of primary herpes simplex virus in asymptomatic pregnant women. Elongated antenatal screening for herpes simplex 2 by serological markers and avidity IgG should be rigorously implanted in screening program to avert fetal complications
Middle Miocene syn-rift sequence on the central Gulf of Suez, Egypt: Depositional environment, diagenesis, and their roles in reservoir quality
No full textThe middle Miocene sediments, a key oil reservoir within the syn-rift structures of the Gulf of Suez, have received limited research attention despite their geological importance. To bridge this gap, we analyzed well cores and petrophysical data from the middle Miocene sandstone-shale sequence (Sidri Member) in the Belayim field, one of Egypt’s major oil fields, to assess the depositional and diagenetic characteristics and evaluate reservoir quality. It is subdivided into three sandstone units separated by calcareous shale interbeds. The units show distinct lateral and vertical distribution, reflecting an upward change in depositional environment, transitioning from shoreface, deltaic condition, to embayment settings, interrupted by shale deposition during transgression episodes. The sediments originated from uplifted and tilted rift margins along NW-SE trending faults. During the syn- to post-rift burial to depths exceeding 2.5 km, diagenetic processes, including compaction, dissolution, and cementation, altered the sandstones’ primary properties, resulting in significant petrophysical variations. Porosity reaches up to 30% in well-sorted, medium-grained sandstones with dissolution, corresponding to bulk density as low as 2.1 g/cm3 and permeability up to 1000 mD, while cementation reduced porosity in certain intervals, creating heterogeneity in grain density and permeability. Reservoir quality of the sandstones ranges from poor to excellent with variable oil saturation. Notably, the lower sandstone unit, located within an anticline structure, displays good to excellent quality and up to 70% oil saturation. These findings highlight the influences of syn-rift dynamics in shaping the middle Miocene sequence and the potential for optimizing hydrocarbon exploration and production strategies across the region
Maastrichtian oil shale deposition on the southern Tethys margin, Egypt: Insights into greenhouse climate and paleoceanography
No full textLate Campanian Climatic-Continental Weathering Assessment and Its Influence on Source Rocks Deposition in Southern Tethys, Egypt
No full textClimatic variability and silicate weathering are remarkable features throughout the Late Cretaceous period. Late Campanian black shale is considered the most significant silicate source rock in the southern Tethys. Here, we used mineralogical and geochemical data to evaluate the continental weathering intensity and climatic changes as well as their impact on the deposition of the Late Campanian black shale in the Western Desert of Egypt. The studied black shale has a relatively high concentration of Al, Fe, Mg, Ca, Sr, Ga, Co, Cr, and V when compared to the average Post-Archean Australian Shales (PAAS). The studied samples have elevated values of Ga/Rb, and low values of Rb/Sr, Sr/Cu, and K2O/Al2O3, supporting the deposition of Late Campanian shale under warm/humid conditions. Furthermore, the average chemical index of alteration (CIA, 78.6%), chemical index of weathering (CIW; 83.8%), C-value (1.26), Fe/Mn (408), and Mg/Ca (1.54) reveal the predominance of warm/humid climate. The chemical weathering proxies (CIA, CIW, PIA, LnAl2O3/Na2O) and ACNK diagram imply that the Late Campanian samples were exposed to a moderate grade of chemical alteration. The deposition of black shale occurred under high seawater salinity conditions based on Sr/Ba (Avg = 3.6). Additionally, the weathering indices are well correlated with paleoclimatic proxies, suggesting that weathering intensity is strongly affected by paleoclimate. However, chemical weathering during the Late Campanian has a weak influence on oceanic nutrient fluxes. No substantial impact of the paleoclimate during the deposition of Late Campanian black shale on water salinity was reported
Geochemical fingerprinting of Maastrichtian oil shales from the Central Eastern Desert, Egypt: Implications for provenance, tectonic setting, and source area weathering
No full textOccurrence Patterns and Enrichment Influencing Factors of Trace Elements in Paleogene Coal in the Fushun Basin, China
No full textThe
occurrence forms of trace elements in coal are of great significance
for the clean utilization, abnormal enrichment, and recovery of beneficial
elements in coal. The Fushun Basin in Northeast China has thick coal
deposits which provide a good opportunity for studying their geochemistry.
This study aims to estimate the element enrichment of Paleogene coal
seams and their influencing factors during deposition based on statistical
and geochemical analyses. Compared with world hard coals, coals in
the Fushun Basin feature enrichment of Ga and Sb (CC > 5), slight
enrichment of V, Cr, Co, Ni, As, Rb, Zr, Nb, and Cd (2 < CC <
5), and depletion of B, Tl, Bl, and U (CC < 0.5). The CC values
of the remaining elements (0.5 < CC < 2) are close to the average
values for world hard coals. The main carriers of Ga, Co, Rb, Mo,
As, Se, Pb, V, and Li are potassium, iron, and sulfate minerals and
those of Cd, Cr, Ni, Sb, Th, Sn, U, Hf, Zr, Cs, Ta, and Nb are clay
minerals. The CIA, Sr/Cu, Rb/Sr, and Ga/Rb values suggest that the
studied coal seam formed under humid/warm climatic conditions. The
coal seam is mainly derived from intermediate source rocks and sandstone
or mudstone source rocks which were exposed to intensive chemical
weathering and deposited in a freshwater setting. Additionally, paleoweathering,
paleoclimate, detrital input, and provenance all contributed to the
enrichment of geochemical elements in the studied Paleogene coal.
The results of this study are preliminary, and the authors will continue
to conduct mineralogical analysis
