Petroleum geological characteristics and exploration targets of the oil-rich sags in the Central and West African Rift System

Based on seismic,drilling,and source rock analysis data,the petroleum geological characteristics and future exploration direction of the oil-rich sags in the Central and West African Rift System(CWARS)are discussed.The study shows that the Central African Rift System mainly develops high-quality lacustrine source rocks in the Lower Cretaceous,and the West African Rift System mainly develops high-quality terrigenous organic matter-rich marine source rocks in the Upper Cretaceous,and the two types of source rocks provide a material basis for the enrichment of oil and gas in the CWARS.Multiple sets of reservoir rocks including fractured basement and three sets of regional cap rocks in the Lower Cretaceous,the Upper Cretaceous,and the Paleogene are developed in the CWARS.Since the Late Mesozoic,due to the geodynamic factors including the dextral strike-slip movement of the Central African Shear Zone,the basins in different directions of the CWARS differ in terms of rifting stages,intervals of regional cap rocks,trap types and accumulation models.The NE-SW trending basins have mainly preserved one stage of rifting in the Early Cretaceous,with regional cap rocks developed in the Lower Cretaceous strata,forming traps of reverse anticlines,flower-shaped structures and basement buried hill,and two types of hydrocarbon accumulation models of"source and reservoir in the same formation,and accumulation inside source rocks"and"up-source and down-reservoir,and accumulation below source rocks".The NW–SE basins are characterized by multiple rifting stages superimposition,with the development of regional cap rocks in the Upper Cretaceous and Paleogene,forming traps of draping anticlines,faulted anticlines,antithetic fault blocks and the accumulation model of"down-source and up-reservoir,and accumulation above source rocks".The combination of reservoir and cap rocks inside source rocks of basins with multiple superimposed rifting stages,as well as the lithologic reservoirs and the shale oil inside source rocks of strong inversion basins are important fields for future exploration in basins of the CWARS.

Assessment of the Physical Capabilities of Heart Failure Patients before and after Cardiovascular Rehabilitation: A Study of 125 Patients from West Africa, Dakar, Senegal

Background: Cardiac rehabilitation represents a critical therapeutic strategy for patients suffering from chronic heart failure. The physical capacity of patients with heart failure, assessed using the exercise test and the 6-minute walk test, is the measure of the patient’s overall functional ability to perform physical activities and tolerate exercise loads. The objective of this study was to assess the impact of cardiac rehabilitation on patients’ physical capabilities and to conduct a thorough comparison of data obtained via exercise testing and the 6-minute walk test before and after the rehabilitation programme. Methods: This was a descriptive and analytical cross-sectional study, conducted from 1 February 2021 to 31 June 2022. Included were heart failure patients who had participated in an outpatient cardiovascular rehabilitation programme. The collected data included anamnestic, clinical, paraclinical data, and the 6-minute walk test. Informed consent was obtained. Data analysis, word processing, and charting were performed using Microsoft Word 2016, Excel 2013, and Sphinx version 5.1.0.2. Data analysis was performed using SPSS (Statistical Package for Social Sciences) version 24.0. Any difference less than 0.05 was considered statistically significant. Results: In a Senegalese study, heart failure patients undergoing rehabilitation in a cardiac unit represented 45.59% of all cases, with a prevalence rate of 3.21%. The average participant was 57.97 years old, with those aged 61 to 70 forming the largest group (35.5%). The study noted a male predominance (sex ratio of 2.1) and identified dyslipidaemia (80.6%) and sedentarism (71%), as prevalent cardiovascular risk factors. All participants initially suffered from NYHA stage 2 or 3 dyspnoea, yet 80.65% showed no symptoms following rehabilitation. Significant improvements were recorded in resting heart rate (from 79 to 67 bpm), and the 6-minute walk test distance (from 328 m to 470 m). Enhanced exercise tolerance and walking test outcomes were particularly notable in patients with LVEF ≥ 50%, women, non-obese individuals, those initially walking less than 300 m, achieving more than 3 METs, and non-smokers. Conclusion: The findings underscore the effectiveness of cardiovascular rehabilitation in improving symptoms, physical capability, and overall quality of life for heart failure patients in Senegal.

Westerlies Affecting the Seasonal Variation of Water Vapor Transport over the Tibetan Plateau Induced by Tropical Cyclones in the Bay of Bengal

This study investigates the activity of tropical cyclones(TCs)in the Bay of Bengal(BOB)from 1979 to 2018 to discover the mechanism affecting the contribution rate to the meridional moisture budget anomaly(MMBA)over the southern boundary of the Tibetan Plateau(SBTP).May and October–December are the bimodal phases of BOB TC frequency,which decreases month by month from October to December and is relatively low in May.However,the contribution rate to the MMBA is the highest in May.The seasonal variation in the meridional position of the westerlies is the key factor affecting the contribution rate.The relatively southern(northern)position of the westerlies in November and December(May)results in a lower(higher)contribution rate to the MMBA.This mechanism is confirmed by the momentum equation.When water vapor enters the westerlies near the trough line,the resultant meridional acceleration is directed north.It follows that the farther north the trough is,and the farther north the water vapor can be transported.When water vapor enters the westerlies from the area near the ridge line,for Type-T(Type-R)TCs,water vapor enters the westerlies downstream of the trough(ridge).Consequently,the direction of the resultant meridional acceleration is directed south and the resultant zonal acceleration is directed east(west),which is not conducive to the northward transport of water vapor.This is especially the case if the trough or ridge is relatively south,as the water vapor may not cross the SBTP.

Effects of Natural Processes on Sea Level Change along the West African Coastline

Coastal hazards induced by meteo-marine forcing are exacerbated by sea level change along the West African coastline. Changes in sea level are induced by ocean processes such as ocean heat content and river discharge. However, although these processes control largely change in sea level, they remain poorly understood. This study analyzes changes in ocean heat content, river discharge, and sea level and establishes an interconnection between these parameters using several statistical methods over the 1993-2021 period. Results showed a significant correlation between sea level and ocean heat content at 2000 m depth. The yearly minimum value appears in July from Cote d’Ivoire to Benin, whilst this value appears in June in Nigeria. The temporal variability of ocean heat content, river discharge and sea level along the West African coastline exhibits three or four periods interrupted by some breakpoints with unequal duration. The results indicate that the 1993-2000 period was dominated by an increasing ocean heat content along the coastline, while the period after the 2000s exhibits mostly a decreasing trend. Positive and negative trends characterized river discharge and sea level along this coastline. The result of multiple linear regression between sea level, river discharge and ocean heat content is a good approximation of sea level trend along the West African coastline. The results of this study could be used to predict future sea level trends along the coast.

Endoscopic submucosal dissection for early gastric cancer:A major challenge for the west

Gastric cancer(GC)is the 5th most common cancer and the 3rd most common cause of cancer mortality worldwide.Two main endoscopic resective techniques exist for early GC(EGC):Endoscopic mucosal resection(EMR)and endoscopic submucosal dissection(ESD).ESD has been widely embraced in the last decade because it allows radical en bloc resections and is associated with better outcomes,as compared to EMR.However,the lack of training opportunities and flat learning curve due to low volume of EGC cases represent major obstacles to obtain proficiency on ESD in the West.As this procedure is highly efficient for the treatment of EGC,dedicated training programs with a stepwise approach and updated guidelines for ESD embracement are needed in Western countries.

Geology and S-Pb isotope geochemistry of the Hatu gold deposit in West Junggar,NW China:Insights into ore genesis and metal source

The Hatu gold deposit is the largest historical gold producer of the West Junggar,western China,with an Au reserve of about 62 t.The orebodies were controlled by NE-,EW-,and NW-trending subsidiary faults associated with the Anqi fault.This deposit exhibits characteristics typical of a fault-controlled lode system,and the orebodies consist of auriferous quartz veins and altered wall rocks within Early Carboniferous volcano-sedimentary rocks.Three stages of mineralization have been identified in the Hatu gold deposit:the early pyrite-albite-quartz stage,the middle polymetallic sulfides-ankerite-quartz stage,and late quartz-calcite stage.The sulfur isotopic values of pyrite and arsenopyrite vary in a narrow range from-0.8‰to1.3‰and an average of 0.4‰,the near-zeroδ~(34)S values implicate the thorough homogenization of the sulfur isotopes during the metamorphic dehydration of the Early Carboniferous volcano-sedimentary rocks.Lead isotopic results of pyrite and arsenopyrite(^(206)Pb/^(204)Pb=17.889-18.447,^(207)Pb/^(204)Pb=15.492-15.571,^(208)Pb/^(204)Pb=37.802-38.113)are clustered between orogenic and mantle/upper crust lines,indicating that the lead was mainly sourced from the hostrocks within the Early Carboniferous Tailegula Formation.The characteristics of S and Pb isotopes suggest that the ore-forming metals of the Hatu orogenic gold deposit are of metamorphogenic origin,associated with the continental collision between the Yili-Kazakhstan and Siberian plates during the Late Carboniferous.

Architecture and exploration target areas of the Senegal Basin,West Africa

The recent discovery of large oil and gas fields in the deep-water of the Senegal Basin has drawn global attention.Despite this,several exploration wells in this area fail,which can be primarily contributed to a lack of understanding of the basin's structures and hydrocarbon accumulation conditions.This study examines these characteristics utilizing gravity,seismic and drilling data,and finally makes a comparison with the Cote d’Ivoire Basin,a typical transform margin basin in the South Atlantic.The results suggest that the Senegal Basin,influenced by multiple transform faults and a weak Paleozoic basement,experienced three evolutionary stages:rifting,transitional,and drifting.Each stage contributed to the development of distinct depositional sequences-syn-rift sequences,sag sequences,and continental margin sequences,respectively.The Triassic-Early Jurassic rifting stage predominantly formed continental deposits,like fluvial,lacustrine,and deltaic deposits,in the syn-rift sequences.The Middle-Late Jurassic transitional stage,influenced by transform faults,witnessed the formation of marginal ridges or submarine uplift zones.These zones,in conjunction with landward high terrains,formed a restricted environment promoting the development of source rocks in the sag sequences.During the drifting stage,three types of reservoirs,namely platform carbonate rocks,deltas,and slope-floor fans were formed.Notably,large-scale hydrocarbon reservoirs have been found in the deltas and the slope-floor fans both in the Senegal Basin and the Cote d’Ivoire Basin.The Upper Jurassic-Aptian platforms exhibit thick carbonate rocks and organic reefs on their edges,suggesting substantial potential for hydrocarbon exploration in the Senegal Basin.

Could ERA5 Deliver Better Climate Services Than ERA-Interim over the West African Sahel Region?

Our paper assessed the improvement performance of the reanalysis(ERA5)compared to ERAI(ERA-Interim)both from the ECMWF(European Center for Medium-Range Weather Forecast)in representing the WAM(West African Monsoon)dynamic.Our aim is to evaluate the reliability of ERA5 to deliver better climate services than ERAI in the West African Sahel region.Two complementary observational databases namely the CRU(Climate Research Unit)and the GPCC(Global Precipitation Climatology Center)data are used to evaluate precipitation and temperature representation by the two reanalysis.Otherwise,the representation of some major features of the WAM system,such as the SHL(Saharan Heat Low),the AEJ/TEJ(African and Tropical Easterly Jets)was assessed using the two reanalysis data.The obtained results show a better representation of the seasonal accumulated precipitation and average temperature by ERA5 compared to ERAI with higher spatial correlation and lower bias relative to the observations.Furthermore,ERAI appears to be rainier than ERA5 but ERA5 produces more heavy rainfall days.During the period of intense monsoon,the frequency of the SHL is higher for ERAI which would favor intensification of monsoon inflow and depth.The lower SHL frequency observed in the ERA5 could explain the observed weakening intensity of AEJ which is favorable for moist conditions over the Sahel.These findings confirm the progress made by ERA5 compared to ERAI in representing the WAM dynamic and demonstrate its reliability for delivering better climate services over the West African Sahel.

Control of the Dust Vertical Distribution over Western Africa by Convection and Scavenging

Saharan dust represents more than 50%of the total desert dust emitted around the globe and its radiative effect significantly affects the atmospheric circulation at a continental scale.Previous studies on dust vertical distribution and the Saharan Air Layer(SAL)showed some shortcomings that could be attributed to imperfect representation of the effects of deep convection and scavenging.The authors investigate here the role of deep convective transport and scavenging on the vertical distribution of mineral dust over Western Africa.Using multi-year(2006-2010)simulations performed with the variable-resolution(zoomed)version of the LMDZ climate model.Simulations are compared with aerosol amounts recorded by the Aerosol Robotic Network(AERONET)and with vertical profiles of the Cloud-Aerosol Lidar with Orthogonal Polarization(CALIOP)measurements.LMDZ allows a thorough examination of the respective roles of deep convective transport,convective and stratiform scavenging,boundary layer transport,and advection processes on the vertical mineral dust distribution over Western Africa.The comparison of simulated dust Aerosol Optical Depth(AOD)and distribution with measurements suggest that scavenging in deep convection and subsequent re-evaporation of dusty rainfall in the lower troposphere are critical processes for explaining the vertical distribution of desert dust.These processes play a key role in maintaining a well-defined dust layer with a sharp transition at the top of the SAL and in establishing the seasonal cycle of dust distribution.This vertical distribution is further reshaped offshore in the Inter-Tropical Convergence Zone(ITCZ)over the Atlantic Ocean by marine boundary layer turbulent and convective transport and wet deposition at the surface.

Influence of Continental Atmospheric Forcing on the Decadal Variability of the West African Monsoon

The West African Monsoon (WAM) is characterized by strong decadal and multi-decadal variability and the impacts can be catastrophic for the local populations. One of the factors put forward to explain this variability involves the role of atmospheric dynamics, linked in particular to the Saharan Heat Low (SHL). This article addresses this question by comparing the sets of preindustrial control and historical simulation data from climate models carried out in the framework of the CMIP5 project and observations data over the 20th century. Through multivariate statistical analyses, it was established that decadal modes of ocean variability and decadal variability of Saharan atmospheric dynamics significantly influence decadal variability of monsoon precipitation. These results also suggest the existence of external anthropogenic forcing, which is superimposed on the decadal natural variability inducing an intensification of the signal in the historical simulations compared to preindustrial control simulations. We have also shown that decadal rainfall variability in the Sahel, once the influence of oceanic modes has been eliminated, appears to be driven mainly by the activity of the Arabian Heat Low (AHL) in the central Sahel, and by the structure of the meridional temperature gradient over the inter-tropical Atlantic in the western Sahel.

Solar cycles during the seventeenth century revealed by equatorial aurora records

Solar cycles are fundamental to astrophysics,space exploration,technological infrastructure,and Earth's climate.A better understanding of these cycles and their history can aid in risk mitigation on Earth,while also deepening our knowledge of stellar physics and solar system dynamics.Determining the solar cycles between 1600 and 1700-especially the post-1645 Maunder Minimum,characterized by significantly reduced solar activity-poses challenges to existing solar activity proxies.This study utilizes a new red equatorial auroral catalog from ancient Korean texts to establish solar cycle patterns from 1623 to 1700.Remarkably,a further reevaluation of the solar cycles between 1610 and 1755 identified a total of 13 cycles,diverging from the widely accepted record of 12 cycles during that time.This research enhances our understanding of historical solar activity,and underscores the importance of integrating diverse historical sources into modern analyses.

Analysis of Gardening Based on the Unique Zonal Water System of Slender West Lake

Yangzhou Slender West Lake is narrow in shape. It is 4.3 km in total length with the width of about 100 m. It is a typical zonal water system. Through the research of its spatial structure, space sequence and view borrowing the garden bridges of Yangzhou Slender West Lake, the unique gardening method of zonal water system was expatiated.

Primary Study on Reasons for the Growth Re-cession of Fragrant Camphor Trees at the West Lake Scenic Area and Diagnosis Procedure

Fragrant camphor tree is the city tree of Hangzhou which takes a large proportion of the ancient trees in Hangzhou City. Recently, with the free open of the attractions around the West Lake and the implementation of the comprehensive pro- ject for protecting the West Lake, a part of ancient fragrant camphor trees are fac- ing problems such as altered living conditons. Some of them are showing a decline in growth vigor or even close to death, which will produce extremely negative influ- ences on the maintaining and sustainable development of the West Lake Scenic Area if without any timely measures for the rescue and rejuvenation of the trees. Therefore, strengthening the protection and management of ancient fragrant camphor trees at the West Lake Scenic Area and carrying out researches on the procedure for diagnosing the reasons for the growth recession of the ancient fragrant camphor trees at the West Lake Scenic Area are of great significance for the future protec- tion and rejuvenation of the ancient trees around the West Lake. The factors influ- encing the growth of ancient trees and indexes for judging the growth condition were listed and the reasons for the growth recession were systematically summa- rized in this paper. In addition, measures for the rejuvenation of the ancient fragrant camphor trees were also simply discussed.

Study on Environmental Capacity and Sustainable Development Strategy of Scenic Areas ——Taking the Scenic Area of Slender West Lake in Yangzhou for an Example

Taking the scenic area of Slender West Lake in Yangzhou for an example, the quantitative evaluation model of environmental capacity and impact factors limiting sustainable development of scenic area were put forward, and targeted control measures were correspondingly proposed.

Prospects for Channel Construction of Sending Power from Westto East in the Next 10 Years

This paper describes the planned power transmission from west to east through three channels. It presents the main characteristics of these three channels and the problems need to be solved.

The Criticism of Social Realities in the Three Worlds after the Human World of The Journey to the West

The three worlds after the human world in The Journey to the West, in spite of their religious elements, their implicit moralizing, and their involved allegory, hold up a mirror to the social vices of the author's day, showing on the one hand the corruption, injustice, ava rice, lust, faction, perfidiousness and cruelty among the ruling classes, and on the other hand the miseries of the oppressed.

Canadian West Exploitation in the Context of American Threat of Annexation

America had been attempting to annex Canadian West and posed a threat to the security of the fledgling country. Therefore the antipathy towards America as well as independent-nation complex of Canadians drove Canadian government to incorporate the west exploitation into the national strategy of creating an independent country. Canadian west exploitation thus took on some distinctiveness.

The Criticism of Social Realities in the Human World of The Journey to the West

Given the descriptions of all those unworthy kings in the human world,The Journey to the West is more of a realistic work of fiction than a fantasy.Though the story comprises many superstitious elements,it is told in a very vivid and convincing way and it holds numerous indirect references to the conditions of the author's own day.The book is the author's most forceful means of criticizing the ugly appearances of the ruling classes of his time.

A Brief Analysis of the Themes of The Journey to the West

The Journey to the West has adopted a conventional theme--life is a journey;in order to deliver one's soul,one has to go on the path of salvation.The purpose of this paper is to examine what steps the author has taken to enlighten the readers as to the progress of spiritual salvation.In view of this purpose,the analysis will be focused on the preaching of religious doctrines and the criticism of social realities in the novel.

Tectonic evolution of the West Kunlun Orogenic Belt along the northern margin of the Tibetan Plateau:Implications for the assembly of the Tarim terrane to Gondwana

The West Kunlun orogenic belt(WKOB) along the northern margin of the Tibetan Plateau is important for understanding the evolution of the Proto-and Paleo-Tethys oceans. Previous investigations have focused on the igneous rocks and ophiolites distributed mostly along the Xinjiang-Tibet road and the China-Pakistan road, and have constructed a preliminary tectonic model for this orogenic belt. However, few studies have focused on the so-called Precambrian basement in this area. As a result, the tectonic affinity of the individual terranes of the WKOB and their detailed evolution process are uncertain. Here we report new field observations, zircon and monazite U-Pb ages of the "Precambrian basement" of the South Kunlun terrane(SKT) and the Tianshuihai terrane(TSHT), two major terranes in the WKOB. Based on new zircon U-Pb age data, the amphibolite-facies metamorphosed volcanosedimentary sequence within SKT was deposited during the late Neoproterozoic to Cambrian(600-500 Ma), and the flysch-affinity Tianshuihai Group, as the basement of the TSHT, was deposited during the late Neoproterozoic rather than Mesoproterozoic. The rock association of the volcano-sedimentary sequence within SKT suggests a large early Paleozoic accretionary wedge formed by the long-term lowangle southward subduction of the Proto-Tethys Ocean between Tarim and TSHT. The amphibolitefacies metamorphism in SKT occurred at ca. 440 Ma. This ca. 440 Ma metamorphism is genetically related to the closure of the Proto-Tethys Ocean between Tarim and the Tianshuihai terrane, which led to the assembly of Tarim to Eastern Gondwana and the final formation of the Gondwana. Since the late Paleozoic to early Mesozoic, the northward subduction of the Paleo-Tethys Ocean along the HongshihuQiaoertianshan belt produced the voluminous early Mesozoic arc-signature granites along the southern part of NKT-TSHT. The Paleo-Tethys ocean between TSHT and Karakorum closed at ca. 200 Ma, as demonstrated by the monazite age of the paragneiss in the Kangxiwa Group. Our study does not favor the existence of a Precambrian basement in SKT.