Geophysical datasets, namely, electrical resistivity, induced polarization, magnetic susceptibility were measured and aeromagnetic interpreted on the Subika concession of Newmont Ghana Gold Limited in order to delineate and model the zone of gold mineralization. The electrical resistivity and induced polarization results delineated the gold mineralized zone as a narrow discrete resistor (>4900 ohm m) and high chargeability (>7.2 ms) zone with a strike length of about 2 km. A strip log plots of 12 diamond drilled core samples showed the zone of mineralization with high alteration and low magnetic susceptibility. Analysis of laboratory magnetic susceptibility measured on selected samples from the pit and selected core samples from the mineralized zones showed a negative correlation between the magnetic susceptibility and gold grades with a correlation coefficient of -0.2 and -0.74, respectively. Similarly, magnetic depth slice produced from the 3D model of the aeromagnetic data depicts the zone of gold mineralization with a low magnetic signature. The zone mineralization was also observed to be striking in the north-east direction. Mineralogical analyses of rock samples revealed alteration processes such as carbonization, sericitization, silicification, chloritization and sulphidation resulting from hydrothermal alteration which accounted for the low magnetic and the magnetic susceptibility signatures of the mineralization zones. The strong resistivity and chargeability response of the mineralized zones are therefore attributed to the silicification and sulphidation alteration, respectively. The results show the effectiveness of applying integrated geophysical, petrophysical as well as mineralogical study in revealing gold mineralization potential of the Subika deposit and the Sefwi belt as a whole.
Results of analyses on localized jointing system are presented to study the link of groundwater inflow and joint orientations along the 2000 m excavation of Tunnel Boring Machine (TBM-1) site, Karak in conjunction with the construction of Pahang-Selangor Raw Water Transfer Tunnel project. Geology along the tunnel route is predominantly the Main Range Granite Batholith with a lesser extent of metasedimentary rocks of the Karak Formation. Structurally, TBM-1 is dominated by joints oriented at N-S, NW-SE, and NE-SW directions. Strike slip faults that cross-cut the intrusive Main Range Granite rocks trending faults formed the most prominent structures in the vicinity of the Karak. This section of tunnel alignment consists of 2000 meters in length of Ch.8,821.77 m to Ch.10,821.77 m; 456 joints were mapped to create anisotropic conditions of rock section. Eleven significant locations experienced stoppages, thereby affecting the TBM daily progress, and such stoppages were mainly caused by sudden high-pressure groundwater inrushes or wet joint condition. Potential leakage places are identified by three main types of joints orientations. The most permeable tunnel section is in parallel with the main lineament orientation, followed by perpendicular to the tunnel drive direction, and crossing some voids that create pocket water zones.
Figure 1Figure 21. Tell us about your work at the Swedish Museum of Natural HistoryFigure 1. Ellen Kooijman.Figure 2. In the Vegacenter.I work as a Senior Researcher in isotope geology and I am hea...
Figure 1Figure 2Figure 31. What is your background and experience? How did you get to the role that you are in today?I’m a geographer—I have a BA & PhD in geography and an MS in ecology. I’ve speci...
Santhiagu A, India Emmanuel Mawuli Abalo, Ghana Fidelis Abam, Nigeria Akbar Abbasi, Cyprus Haider Abd, Iraq Saleh Abd El-Aleem, Egypt Juman Abdeen, Sri Lanka Shehata Abdel Raheem, Saudi Arabia Abdelhakim Abdelhadi, Saudi Arabia Sbihi Abdelkader, France Oday Abdullah, Germany Dr Rozi Abdullah, Malaysia Basma Abbas Abdulmajeed, Iraq Alessandro Abena, United Kingdom Mohamed Abosaf, United Kingdom Omar Abu Arqub, Jordan Ahmed Abul’Wafa, Egypt Leonardo Acho, Spain Olusola Adesina, Nigeria Olanrewaju Adesusi, Nigeria Philip Adewuyi, Nigeria Michael Kanisuru Adeyeri, Nigeria Behnam Adhami, Islamic Republic Of Iran Hojjatollah Adibi, Islamic Republic Of Iran Daniel Adu, China George Affenzeler, United States Richard Afolabi, Nigeria Neelofar Afzal, India Pradeep Agarwal, India Aaron Agbo, Ghana Olayinka Agboola, Nigeria Stephen Agyeman, Ghana Abdalqader Ahmad, United Kingdom Muhammad Abbas Ahmad Zaini, Malaysia Syed Hassan Ahmed, China Farooq Ahmed, Pakistan Morteza Aieneravaie, Islamic Republic Of Iran Abel Airoboman, Nigeria Abiola Ajayeoba, Nigeria Priya Ak, India Ali Akbari Motlagh, Islamic Republic Of Iran Andac Akdemir, Turkey Basil Akinnuli, Nigeria Isabelle Akkerman, Germany Mudathir Akorede, Nigeria Alireza Akrami, Islamic Republic Of Iran Isam Al Zubaidi, Canada Guido Ala, Italy Ahmed Abdulamier Hussain Al-Amiery, Malaysia Alma Y. Alanis, Mexico Mohamed Al-Ashhab, Egypt Rawaa Al-Dabbagh, Iraq Alessio Alexiadis, United Kingdom Lokman Ali, Bangladesh Javed Ali, Germany M. D. S. Aliyu, Saudi Arabia Farideh Alizadeh, Malaysia Hassan Aljaberi, Malaysia Dhiya Al-Jumeily, United Kingdom Ghazaleh Allameh, Islamic Republic Of Iran Sana Almi, Algeria Karam Al-Obaidi, Malaysia Francisco Alonso, Spain Ehab Alshamaileh, Jordan Wisam Al-Shohani, United Kingdom Luis Alvarez-Icaza, Mexico Baurzhan Alzhanov, Kazakhstan Hussein Alzoubi, Jordan Amirmostafa Amirjani, Islamic Republic Of Iran Mutiu Amosa, South Africa Sanjeev Anand, India Yatheshth Anand, India Vivek Anandaan, India Parinya Anantachaisilp, Thailand Pradeep Anjana, India Sadiya Anjum, India Iyswarya Annapoorani, India Eugene Ansah, Ghana Kashif Ansari, India Mohammad Khalid Ansari, India Emmanuel Anye Ngang, United Kingdom Zoubir Aoulmi, Algeria Amir Arablouei, United States Dominique Armellini, Canada Yogendra Arya, India Tatsunori Asaoka, Japan Nestor Asiamah, Ghana Alireza Aslani, Finland Nikos Aspragathos, Greece Samuel Asumadu-Sarkodie, Ghana Abdullah Ates, Turkey Youssef Attai, Egypt Farnaz Avarzamani, Islamic Republic Of Iran Wael Awad, Jordan Hediye Aydın, Turkey Sohail Ayub, India Faieza Aziz, Malaysia Nagarajan B, India B.Chitti Babu, India Sudhakar Babu, India Senior Editors, Cogent Engineering (2018), 5: 1433607 https://doi.org/10.1080/23311916.2018.1433607
Implementation of terrestrial laser scanning creates new opportunities in the analysis of processes occurring in the environment. Terrestrial laser scanning (TLS) enables fast, precise mapping of land relief and dimensions of technical structures. TLS allows moving from traditional methods, such as point measurement, to differential analyses of a relief model. TLS allows accurate analyses of land relief changes and erosion phenomena, both in terms of the processes intensity and range, and the initial and intensifying events. The paper presents the authors' experiment with the use of the TLS technology in erosion processes monitoring and analyses. The authors present the methodology of using TLS which contributed to the acquisition of reliable results by providing optimal conditions for the research. The paper shows the effects of laser scanning in order to analyse the intensity of soil erosion in mountainous forest area with a large number of measurement stations, which resulted in a dense points cloud. Differential model method allowed to evaluate erosion phenomena in the form of rills resulting from surface flushing, which is impossible to assess by traditional methods of erosion measurements. In the paper, we showed the necessity to choose the proper coordinate system (object or scanner) for the analysis of the landslide, depending on structure and direction of the soil masses movement. The application of the object coordinate system showed greater erosion phenomena range (ca 12%) on buttress stabilizing landslide and ca 44% on natural landslide, in which the application of the object coordinate system increases the number of observations by 40%.
In regions of enhanced weathering and erosion, such as Papua New Guinea, our ability to examine a complete geological record can become compromised by the absence of in situ outcrops. In this study, we provide an example of the insights that can be gained from investigations of secondary deposits. We sampled matrix material and clasts derived from an isolated conglomerate outcrop within a landscape dominated by lowland tropical forest of the southeast Papuan Peninsula, and mapped as belonging to the Cloudy Bay Volcanics. Nine variations of volcanic rock types were identified that range from basalts to trachyandesites. Major and trace element geochemistry characterize the volcanic arc assemblage as shoshonites and provide evidence for differential magma evolution pathways with a subset of samples marked by heavy REE- and Y-depletion, indicative of high-pressure magma fractionation. Zircon U-Pb dating of the individual volcanic clasts indicates activity of the Cloudy Bay Volcanics was largely constrained to the latest Miocene, between ca. 7 and 5Ma. Of the analyzed zircons, the majority are xenocrystic zircons that provide insight into the provenance of the Papuan Peninsula with potentially significant implications for South West Pacific tectonics. Additional Hf-isotope analysis of the primary igneous zircons suggests a relatively unradiogenic crustal component contributed to magma compositions, which cannot be readily explained by current regional tectonic paradigms.
Evidence of strike-slip deformation in the Inkisi Formation was overlooked for a long time. After controversial characterization, this paper demonstrates that the Inkisi Formation underwent at least two phases of strike-slip deformation accompanied with a compressive component, which created faults that help determine paleostress. Field observations permitted to characterize NW-SE trends sinistral strike-slip faults systems and NE-SW oriented dextral strike-slip faults systems. The strike-slip faults are associated with flower structures in profile view and with damage zones along tips, wall and linking zones in plan view. Both faults systems (sinistral and dextral) initiated from joints, which show similar orientations with faults. Many kinematic indicators of slip sense or extension have enabled to determine the stress stages and the evolution of the structures. The first tectonic phase has a horizontal maximum principal compressive stress sigma(1) of 319 +/- 21,1/03, which probably have a potential correlation with far-field stress propagation which occurs during the subduction of Gondwana south margin in the Permo-Trias. The second tectonic phase with a slightly inclined maximum principal compressive stress sigma(1) of 264 degrees +/- 22,3/12 potentially results from the intraplate stress propagation, due to the opening of the Southern Atlantic Ocean.
The biggest nine well-known natural ponds in the highest elevations of Zagros thrust zone in the northeast of Erbil, Kurdistan region, Iraq, have been taken and synthesized with RS and GIS techniques to reveal the spatial and temporal distribution of the ponds, and to explore the sustainability of these ponds. ENVI 5.1 software was used to detect pond surface area and shapes in different seasons and for 33 years. RS was used to detect land surface temperature (LTS), but GIS was used for maps and calculations of pond area variation. Geology of the area is very complex; formations are different in genetics, age, thickness, and extensions. The regional tectonic forces highly deformed the succession and extension of the geologic formations. i.e. The forces that had made the mountains were very strongly affected the layers and the geologic formations, resulting in many types of folds, faults, overturning layers, thrusting, and many other highly deformed structures. Water-bearing formations are of restricted extensions due to the deformations, with limited and local productivity. The aquifers moved to face impermeable rocks or surface, discharging springs, ponds, and rivers. The ponds are sustaining permanently due to the following reasons: most of the ponds are located on semi-impermeable deposits, weather and LTS throughout the year are less than 25 degrees C, high relative humidity and low evaporation, and they are recharging by direct groundwater and snowmelts.
This paper presents the result of an experimental study on the shear behaviour of a pre-sheared clayey soil. The effect of shear rate on the residual strength of pre-sheared clays was investigated in a ring shear apparatus. A pre-sheared surface was initially developed at a slow rate of 0.1 mm/min. Fast shear rates were then applied to the pre-sheared specimens to investigate the impact of the shear rates on the results. The laboratory results show that there is an immediate tendency for the residual strength to increase with increasing shear rate. Following this, the fast residual strength continues to increase with further displacement, reaching the peak value of fast residual strength (i.e. positive rate effect). Finally, the fast residual strength drops with increasing displacement to a value less than slow residual strength (i.e. negative rate effect). Overall, the relationship between the residual strength and the fast shear rates indicates a positive and negative rate effect based on the shear rates and the shear displacement.
Abstract The study area, Odukpani is underlain by cretaceous sediments of the Calabar Flank. The main aquifers are fractured black shales that are inter-bedded with calcareous sandstones. The aquifers range from confined to unconfined. Water samples were taken from boreholes and shallow hand dug wells for chemical characterization with standard laboratory techniques. Results from the chemical analysis show that the waters are mostly alkaline with the exception of two mildly acidic samples. They depicted low electrical conductivity values and a total dissolved solids range from 13.1 to 341 mg/l which indicate fresh water. Cations levels occur in the order, Ca2+ ˃ Na+ ˃ Mg2+ ˃ K+ ˃ Fe2+ while anions occur as the following order, HCO3− ˃ SO42− ˃ Cl− ˃ CO3− ˃ NO3−. Piper trilinear and stiff plots show that Ca2+ – Na+ – HCO3− is dominant water type. The waters are supersaturated with respect to calcite in five of the samples. The rest have calcite under-saturation. Areas of calcite super-saturations are likely undergoing precipitation of carbonate minerals in the aquifer matrices. Precipitation and dissolution of carbonate minerals within the aquifers are likely contributing to the modification of flow characteristics of the aquifer. Comparison of the water chemistry with standards set by regulatory bodies indicates that the waters are of good quality.
In this study, four models were developed to predict intrinsic constants based on some simple physical parameters as well as clay mineralogy of a reconstituted clay sample. The effect of each predictor on the response was evaluated for each individual clay mineralogy. According to the results, it appears that the void ratio at liquid limit has the greatest effect on clays with a considerable amount of smectite, while the effect of the initial void ratio of such clays is the least amongst other clay minerals. The accuracy of the predictive model increases with the inclusion of clay mineralogy as an input parameter. R-2 increases from 0.978 to 0.99 and from 0.831 to 0.896 for intrinsic parameters of e*(100) and e*(1000), respectively. A simplified method is also presented to determine the virgin compression line of reconstituted clays using the initial void ratio, the void ratio at the liquid limit, and its clay mineralogy.
This study presents the advantages of detailed landscape analysis by UAV (drone hereafter) photogrammetry compared with satellite remote sensing data. First, satellite data are used for generating a coarse-scale land use/land-cover (LULC) map of the study region using conventional GIS techniques. The Advanced Land Observation Satellite-2 (ALOS-2) Phased Array L-band Synthetic Aperture Radar-2 (PALSAR-2) L-Band backscattering data are processed with a multilayer perceptron (MLP) supervised classification for generating a categorical map. The satellite-derived classification map resulted in eight general land-cover types with a ground resolution of 7.5 m, providing a moderate-resolution representation of the island landscapes. Second, the drone's image data are used to collect ground survey information and microscale information of the local site by implementing a structure from motion (SfM) technique to develop mosaicked orthorectified images of the sites. The orthophoto and digital surface model (DSM) derived from the drone-based data had resolutions of 0.05 m and 0.1 m, respectively. The SAR-based LULC map showed an overall accuracy of 78.1%, and the drone-based LULC map had an overall average accuracy of 92.3%. The subset area of the SAR map was compared with the drone-based map and showed average Kappa statistics of 0.375, demonstrating that satellite data cause challenges in correctly delineating the local land environment. The terrain information generated by the SfM method provided a good representation of the topography showing the drastic changes in the environment. The results indicate the usefulness of drone-based landscape analysis for future land-use planning at a local village scale.
1. What made you decide to be a geoscientist?I’ve always been fascinated by the atmosphere. Hurricane Bob hit the state of Rhode Island when I was 11 years old, and I was awestruck. I called our lo...
Land cover changes in the Tampa Bay watershed (Florida) over the past four decades were examined along with precipitation and wind observations to help understand causes of long-term changes in turbidity and chlorophyll concentration within the Tampa Bay estuary. Water quality showed a statistically significant relationship to land cover fraction in the watershed compared to long-term precipitation or wind stress. Redundancy Analyses with Akaike's Information Criterion and non-parametric multiple regressions determined that turbidity and chlorophyll concentration decreased bay-wide from 1974-2012 with increased developed land fraction (R-2 > 0.75, p-value < 0.05). Various segments of the estuary showed different significant responses to developed land (R-2 > 0.75, p-value < 0.05), agricultural land (R-2 > 0.93, p-value < 0.02), bare land (R-2 = 0.77, p-value = 0.001), and wind stress (R-2 = 0.91, p-value = 0.04) at different times of year.
1. What do you do at NASA?I have two major official roles at NASA: (1) doing sea ice research using satellite data and (2) serving as Project Scientist for the Earth-observing satellite named Aqua....
One of the most important applications of remote sensing is presented in mining and exploration of mineral deposits and evaluation of prospective targets. This project discusses how to use remote sensing knowledge in order to make classification and separation of surface rocks in the Dir-o-Morreh mine. The main purpose of this research is to identify the areas containing high-quality basalt. In this regard, we utilize ASTER multi-spectral satellite imagery, which has relatively good spectral and spatial resolution. At the first step, in order to achieve the correct spectral composition of the basalt spectrum, the spectral signature of basalt stone, defined by Johns Hopkins University, was used. Afterward, the basalt extraction index (BEI) was defined regarding the behavior of the ASTER satellite image bands as well as the initial data provided by the owners of the intended study area. Then, the Convolution and Morphology filter was applied over the images to extract high-quality basalt using an appropriate color composition of the images. At the next step, in order to have better visualization, different maps containing different classes were created using the Maximum Likelihood algorithm. Finally, two indices were developed regarding all research data and field investigations in order to extract basalt zones. The first index discovers basalt zones in the study area, and the second one classifies high-quality basalt and altered basalt zones.
International Ocean Discovery Program Sites U1437 and U1436, two intermediate water depth sites located near the Kuroshio Current were studied for planktonic proxies, shell weights, percent fragments, foraminifers concentrations, and benthic/planktonic ratios. Over the last 1 My, the foraminifers assemblages responded to local temperature changes. The taphonomy of these assemblages limits their usefulness as palaeoclimatic records but greatly inform qualitatively of intermediate water mass changes on each side of the Izu Rise. Carbonate dissolution (CD) is pervasive and always more intense during interglacials at the shallowest Site U1436 to the East. Carbonate preservation improved during glacials after 0.6 Ma at U1437B (West) likely signaling changes within the glacial Antarctic Intermediate Water and therefore, its source water the Glacial North Atlantic Intermediate Water from Marine Isotope Stage 16. The first occurrence of a very large Laurentide ice-sheet at the time is proposed as a potential indirect cause for this observation. Both the intensification of carbonate dissolution during each interglacials from MIS17 onwards and the better preservation during succeeding glacials after that are attributed to the increasing influence of the North Atlantic Deep Water and the Glacial North Atlantic Intermediate Water via the Antarctic Intermediate Water during Interglacial and Glacial intervals, respectively.
