Petrophysical properties of bypassed Cenozoic clastic reservoirs in the Cesar sub-basin, Colombia

The Cesar-Ranchería basin has all the necessary elements for the generation, expulsion, and migration of hydrocarbons and considerable potential for coal bed methane (CBM) in Colombia. Previous studies in the Cesar basin focused on understanding the tectonic evolution, stratigraphy, hydrocarbon generation potential, and evaluation of reservoir potential in Cretaceous calcareous units and quartzose sandstones from the Paleocene Barco Formation. These studies had confirmed the existence of an effective petroleum system, with several episodes of oil expulsion and re-emigration in the Miocene period, turning the Cenozoic clastic succession (Barco, Los Cuervos, La Loma, and Cuesta formations) into an element of significant exploratory interest to clarify the potentiality of the basin in terms of hydrocarbon accumulation. The petrophysical parameters of Cenozoic units (shale volume, porosity, water, and oil saturation) were determined by integrating wells log and core samples analyses from three stratigraphic wells. The integration of these results synthesizes the petrophysical behavior of the units. It defines intervals with clay volumes of less than 30%, effective porosity around 20%, which means favorable characteristics as reservoir rocks that need to be considered in future exploratory projects.

Coffee plantation soil characterization using a multi-method approach near the Volcano Nevado del Ruiz, Colombian Central Cordillera

The presence of iron oxides may provide a sensitive indicator of the effects of cropping practices on coffee plantations. Authors characterized the mineral phases present in soil A horizons at three different farms located in the Department of Tolima within the regions of Líbano and Villahermosa. Our analysis includes X-ray diffraction, Mössbauer spectroscopy, and remote sensing to discriminate the distribution of the different magnetic mineral phases. X-ray diffraction was used to identify the mineralogical properties of iron oxide such as hematite, goethite, and ferrihydrite (Fh), as well as tectosilicate minerals such as albite and sanidine. Mössbauer spectroscopy results for samples taken at room temperature indicate the presence of Fe2+ and Fe3+ mineral phases, which possibly correspond to ilmenite or magnetite. Finally, Sentinel-2A multi-spectral imager (MSI) data was used to map the distribution of iron oxides and study the influence of their distribution throughout the study area. A high correlation between Mössbauer spectroscopy and Sentinel-2A MSI data exists throughout the study area. The results suggest that farms close to the main Nevado del Ruíz Volcano have a more significant mineralogical variability. In contrast, more distant farms are characterized by soils with more iron oxides, the product of weathering, erosion, and human activities.

Application of life cycle assessment (LCA) methodology and economic evaluation for construction and demolition waste: a Colombian case study

The construction industry consumes more raw materials and energy than any other economic activity and generates the largest fraction of waste, known as construction and demolition waste (CDW). This waste has significant environmental implications, most notably in South American countries such as Colombia, where it is handled inappropriately. This study evaluated the management processes currently used for fractions of construction and demolition waste generated in Ibagué (Colombia). The environmental impacts of the management of 1 kg of CDW were also calculated. Other CDW management alternatives were evaluated. The percentage of the fraction of the waste and the treatment or management processes used were modified to determine its environmental and economic viability. The information was obtained through telephone interviews and visits to recycling plants, construction companies, quarries, government entities, and inert landfills. It was completed with secondary sources and the Ecoinvent v.2.2 databases. Life Cycle Assessment (LCA) methodology and the SimaPro 8 software were used to calculate the environmental impacts. An economic study of each management process and each alternative was also carried out. A comparison of the other options revealed the current choice contributes most to the environmental impacts in all categories. This study indicates that the most beneficial alternative in environmental and economic terms in Ibagué (Colombia) is where 100% of the metals are recovered, 100% of excavated earth is reused, and 100% of the stone waste is recycled (alternative 3). This alternative remained the most favorable when a sensitivity analysis was carried out with different distances (30 km and 50 km).

Petrographic and geochemical features of Gimo marble, Gole area, Kurdistan Region, Iraq: constraints on its protolith's origin and depositional environment

It is essential to identify marbles' petrographic and geochemical characteristics to determine the palaeo-environmental settings where their carbonate protoliths formed. The petrogenesis of massive Gimo marbles in the Gole area, Kurdistan Region of northeast Iraq, was investigated in this study through a combination of field mapping, petrographic, and geochemical techniques. Petrographic examination of these marbles reveals that mineral compositions are similar in all samples, with both homeoblastic and mosaic textures occurring, in addition to opaque grains that provide evidence of mineralization. Geochemical analyses show that the average calcium carbonate content of the marble is 94.96%; hence, the marble is lithologically characterized as a pure calcite marble. In most samples, the silica content was below 2 wt.%, with high values related to quartz veinlets. A range of geochemical indices and Post-Archean Australian Shale (PAAS–normalized rare earth element (REE) patterns) suggest that the limestone protolith was deposited in a shallow, near-shore marine environment on a continental margin, with very low input of detrital material. The negative Ce anomalies indicate that the protoliths of the Gimo marbles were carbonate rocks of a sedimentary origin.

A comparative soil liquefaction analysis with a Matlab® based algorithm: soiLique

Soil liquefaction is one of the ground failures induced by earthquakes. Determining the safety factor and the settlements are the most common analyses to decrease liquefaction-induced failures and hazards. Scientists have suggested numerous empirical formulas to detect and mitigate liquefaction-based hazards, and they have been used over the decades. This study aims to present a user-friendly and interactive program for deterministic soil liquefaction analyses. The algorithm presented in this study, soiLique, is the first MATLAB® program, including a graphical user interface that provides the deterministic liquefaction analysis with the computation of parameters propounded with the formulas. One of the advantages of soiLique is that it allows picking the physical property of every layer (i.e., fine or coarse), which provides dealing with liquefaction prone layer(s) directly when necessary. Not only can one calculate parameters regarding soil liquefaction with the help of this program, but one also can see graphically supported results. The robustness of soiLique is checked with another soil liquefaction analysis program, SoilEngineering, which was introduced by Ozcep (2010). Calculations were done separately using real SPT data and synthetic data such as VS measurements and CPT data. The real SPT data and synthetic VS data were used to compare soiLique and SoilEngineering (Ozcep, 2010). The present study presents an example of CPT data analysis but could not be used for comparison. Comparisons reveal that outputs of soiLique and results of SoilEngineering showed a good agreement.

Prediction of land degradation by Machine Learning Methods

In this study, three models were used to monitor and predict the GWL and the land degradation index via the IMDPA method. In all models, 70% of the data was applied for training, while 30% of data were employed for testing and validation. Monthly rainfall, TWI index, the distance of the river, Geographic location was the inputs and the level of groundwater was the output of each method. we found that ANN has the highest efficiency, which agrees with other findings. We combined the results of ANN with Ordinary Kriging and produced a groundwater condition map. According to the potential desertification map and groundwater level index, the potential of desertification had become severe since 2002 and was at a rate of 60% of land area, which, due to incorrect land management in 2016, increased to almost 98% of the land surface in the study area. Using ANN, we predicted that around 99% of the area was severely degraded for 2017. We also used latitude and longitude as input variables which improved the model. In addition to the target variable, latitude and longitude play important roles in Ordinary Kriging and decreased the total error of two combined models.

20 July 2017 Bodrum-Kos Earthquake (Mw:6.6) in southwestern Anatolia, Turkey

In the Aegean Sea, the western part of Gökova Gulf, Kos and Bodrum were struck by a 6.6 (Mw) earthquake on July 20, 2017. The fault plane solution for the main shock shows an E-W striking normal type fault with approximately N-S (N4°E) tensional axis (T-axis). Fault plane solutions of 33 aftershocks show two groups of normal type fault with E-W and NE-SW to ENE-WSW orientations. The inversion of the focal mechanisms of the aftershocks yields two different normal faulting stress regimes: one is characterized by an approximately N-S (N5°E) σ3 axis (minimum horizontal stress axis). This extension is obtained from 13 focal mechanisms of aftershocks with approximately E-W direction. The other is characterized by approximately NW-SE (N330°E) σ3 axis. The latter is calculated from 21 seismic faults of aftershocks with approximately NE-SW direction. These aftershocks occurred on relatively small-scale faults that were directed from NE-SW to ENE-WSW, and possibly contributed to expansion of the basin in the west. The 24 focal mechanisms of earthquakes which occurred since 1933 in and around Gökova Basin are introduced into the inversion analysis to obtain the stress state effective in a wider region. The inversion yields an extensional stress regime characterized by an approximately N-S (N355°E) σ3 axis. The E-W directional metric faults, measured in the central part of Gökova Fault Zone bordering the Gökova Gulf in the north, also indicate N-S extension. The NE-SW extension obtained from NE-SW aftershocks appears to be more local and is responsible for the expansion of the western part of the asymmetric Gökova Basin. This N-S extension which appears to act on a regional-scale may be attributed to the geodynamic effects related to the combined forces of the southwestward extrusion of Anatolia and the roll-back process of African subduction beneath Anatolia.

Electrical and magnetic data time series’ observations as an approach to identify the seismic activity of non-anthropic origin

In this work, the authors tried to identify a possible relationship between electromagnetic signals (EM) and seismic events in the lithospheric system in the central region of Colombia. The data, both seismic records and electromagnetic signals, were taken from the catalog of the Seismological Network of the National University of Colombia (RSUNAL) and the catalog of the National Seismological Network of Colombia (RSNC). The project included the design and instrument testing phases for recording seismic signals, electrical potential variations, and magnetic field variations to try to identify possible relationships between these signals. Possible electromagnetic precursors for seismic events were observed, mainly magnetic disturbances, but it was not possible to locate evident electrical anomalies (Seismic Electric Signals - SES). Thus, although the results are not conclusive, the magnetic disturbances identified deserve further long-term analysis.

A prediction method of regional water resources carrying capacity based on artificial neural network

To better predict the water resources carrying capacity and guide the social and economic activities, a prediction method of regional water resources carrying capacity is proposed based on an artificial neural network. Zhaozhou County is selected as the research area of water resources carrying capacity prediction, and its natural geographical characteristics, social economy, and water resources situation are explored. According to the regional water resources quantity and utilization characteristics and evaluation emphasis, the evaluation index system of water resources carrying capacity is constructed to evaluate the importance and correlation of water resource carrying capacity. The pressure degree of water resources carrying capacity is divided into five grades. According to the evaluation standard of bearing capacity, the artificial intelligence BP neural network model is constructed. Based on the main impact factors of water resources carrying capacity in this area, the water resources carrying capacity grade is obtained by weight calculation and convergence iteration by using neural network model and influence factor data to realize the prediction of water resources carrying capacity. The research results show that the network model can meet the demand for precision. The prediction results have a high degree of fit with the actual data, indicating that human intelligence can obtain accurate prediction results in water resources carrying capacity prediction.

Petrologic features of mesoproterozoic lamprophyric dykes from Montevideo (Piedra Alta terrane, South Uruguay)

Mafic dykes of lamprophyric affinity cropping out along the coastal area of Montevideo city are described. These dykes trend N75º-85º and crosscut 2.1 Ga Paleoproterozoic metamorphic units of the Rio de la Plata craton. They show mainly porphyritic textures with phlogopite and clinopyroxene macrocrysts in a groundmass composed of carbonates, phlogopite, augite, and feldspathoids. Ocellar structures filled by leucite, carbonates and fibrous alkaline amphibole are present. The mineralogical assembly allows their classification as lamprophyres (minettes), but according to their chemical nature, they can be classified as alkaline lamprophyres. A crystallization age of 1.42 Ga, by Ar-Ar method (on biotite/phlogopite) was obtained.