scholarly journals DISCOVERY OF NEW KIMBERLITE FIELDS ON THE SOUTHERN SLOPE OF THE LEONE-LIBERIAN SHIELD (Sierra Leone)

2021 ◽  
pp. 118-126
Author(s):  
Oleksandr BOBROV ◽  
Sergii KLOCHKOV ◽  
Serhiy KAKARANZA ◽  
Oleksandr KAKARANZA ◽  
Yurii FEDORISHIN ◽  
...  
Keyword(s):  
Sierra Leone ◽  
Ultramafic Rocks ◽  
Southern Slope ◽  
Rock Matrix ◽  
Geophysical Research ◽  
Optimal Sequence ◽  
Space Images ◽  
Complex Morphology ◽  
Geomorphological Analysis ◽  
Contact Part

During 2017–2018 not far from Sewafeh town, Kono province (Republic of Sierra Leone), we identified a number of previously unknown manifestations of kimberlite magmatism in the form of a system of individual veins localized at the contact of the migmatite basement and Archean ultrabasic massifs, or in the immediate vicinity of ultramafic massifs, which is part of the rocks of the greenstone belt. The optimal sequence of conducting remote sensing studies, such as interpretation of space images of various resolution, neotectonic and geomorphological analysis, SRTM modeling, and then field geological and geophysical research have facilitated this discovery. According to drilling data, kimberlites in different spots of their occurrence (Punduru 1 area) are represented by subvolcanic phlogopite-olivine (with perovskite), and olivine varieties, as well as veins of numerous intensely metasomatic altered kimberlite breccias (Yomby area). Veins of subvolcanic kimberlites are concentrated in the contact part with ultramafic massifs of magmatic and lava (metakomatiite xenoliths) genesis. Kimberlites are the youngest vein formations in the area, crossing even vein pegmatites, the generation of which was provoked by the intrusion of ultramafic rocks in the basement migmatites (Cederholm effect). Kimberlites are present in the section of wells in the form of separate veins of complex morphology and thickness from a few centimeters to 45 cm. In well P1-2 at a depth of 92 m, these are represented by micro porphyry kimberlites of the basaltoid type with microlithic groundmass, altered by secondary metasomatic processes. Porphyry inclusions are represented by pseudomorphs of carbonate-serpentine composition after olivine and rare phlogopite flakes. Olivine crystals of the second-generation act as micro porphyry inclusions. The rock matrix is carbonate. Carbonate is represented by finely crystalline calcite, or replaced by dolomite. In addition to olivine, the groundmass contains relics or pseudomorphs after phlogopite, as well as magnetite, perovskite (it can be replaced by magnetite), secondary apatite. The kimberlites of the Bambawo area are represented by sub-volcanic porphyry basaltoid kimberlites, autolithic kimberlites and kimberlite xenotuff breccias. 

The geochemistry of mafic and ultramafic from the Archaean greenstone belts of Sierra Leone

1983 ◽  
Vol 47 (344) ◽  
pp. 267-280 ◽  
Author(s):  
H. R. Rollinson
Keyword(s):  
Sierra Leone ◽  
Magma Chamber ◽  
Source Region ◽  
Double Diffusion ◽  
Ultramafic Rocks ◽  
Magma Chambers ◽  
Basaltic Rocks ◽  
Ocean Ridges ◽  
Different Depths ◽  
Greenstone Belts

AbstractThe Archaean (c. 2800 Ma) ultramafic rocks in eastern Sierra Leone cut basalt lavas and are mostly olivine-rich cumulates either iron-rich (Fo85–86) and derived from a basaltic or picritic parent, or more magnesian (Fo92–93) derived from an ultramafic melt with c. 18–25 wt. % MgO. In central Sierra Leone the ultramafic rocks are lavas predating tholeiitic basalts.The basalts show a wide variation in Zr/Y, suggesting that garnet was present in the source region of some of these rocks but not others. This implies that melting took place at different depths in the mantle. The REE evidence for basaltic rocks in the upper part of the Nimini belt succession suggests that they were derived from a mantle source region which had already suffered melt extraction. Ti/Zr ratios in the basaltic rocks are also variable and individual belts define different trends on a Ti vs. Zr plot implying that the basaltic rocks evolved in geographically distinct magma chambers. It is likely that the basaltic rocks evolved from a parental liquid with Ti/Zr = 90 via shallow level crystal fractionation. The source region for these rocks therefore had a lower than chondritic Ti/Zr.There are two possible models for the basaltic and ultramafic magmas in the Sierra Leone greenstone belts. First that the ultramafic and basaltic liquids were derived from mantle diapirs of differing size, but originating in the same region of the mantle. Ultramafic liquids were produced in small diapirs, which store large melt fractions, and basaltic liquids in larger diapirs which segregate larger melt fractions. A second model is based upon the double diffusion process suggested for magma chambers at mid-ocean ridges and involves a transient magma chamber from which basalts, derived from parental ultramafic liquids, are erupted, with ultramafic liquids rising directly to the surface when the magma chamber is frozen. The available data does not discriminate between these two models.

Geomorphological analysis of alluvial relief forms of the Kur-Araz lowland

2021 ◽  
Vol 08 (03) ◽  
pp. 24-26
Author(s):  
Ayşən Müşviq qızı Bədəlova ◽  
Keyword(s):  
Key Words ◽  
Space Images ◽  
Genetic Types ◽  
Vertical Fragmentation ◽  
Horizontal Fragmentation ◽  
Geomorphological Analysis

Based on the analysis of space images, it was determined that accumulative landforms prevail in the Kur-Araz lowland and in the foothills. Analysis of images taken at different times shows that these areas are types and subtypes of accumulative plains belonging to completely different genetic types. Key words: Arg GİS, horizontal fragmentation map, vertical fragmentation map

Complex geomorphological characteristics and relief geodynamic features of morphostructural units of the southern slope of the Greater Caucasus

2021 ◽  
Vol 07 (02) ◽  
pp. 61-63
Author(s):  
Qüdrət Tərlan oğlu Məmmədli ◽  
Keyword(s):  
Key Words ◽  
Geological Structure ◽  
Southern Slope ◽  
Greater Caucasus ◽  
River Valleys ◽  
Geomorphological Analysis

According to the modern geodynamic concept of lithosphere pans, the geological structure of the Greater Caucasus in the system of geosynclinal and platform regions is very complex. This situation, along with different conditions for the geomorphological development of the area, led to the formation of a complex and diverse relief with different ridges, massifs, inland basins, river valleys and other small morphostructures and morphosculptures. Key words: Greater Caucasus, southern part of Greater Caucasus, southern slopes, mosfostructure, geomorphological analysis, relief forms

scholarly journals Potensi Panas Bumi Gedongsongo Lereng Selatan Gunung Ungaran Jawa Tengah Berdasarkan Analisis Geosains

2018 ◽  
Vol 2 (1) ◽  
pp. 34
Author(s):  
Rena Juwita Sari
Keyword(s):  
Electric Power ◽  
Geothermal Energy ◽  
Unit Area ◽  
Magnetic Method ◽  
Southern Slope ◽  
Reservoir Temperature ◽  
Energy Potential ◽  
Geophysical Research ◽  
Central Java ◽  
Method Show

<p>Kajian tentang potensi energi panas bumi dan rekomendasi pemanfaatanya telah dilakukan di Gunung Ungaran Jawa Tengah area lokasi candi Gedongsongo. Penelitian bertujuan untuk memperkirakan potensi energi panas bumi lereng selatan Gunung Ungaran, serta membuat skema pemanfaatan energi listrik panas bumi sebagai rekomendasi untuk digunakan di daerah tersebut. Beberapa hasil penelitian yang telah dilakukan pada bidang geofisika, geologi dan geokimia di Gedongsongo lereng selatan Gunung Ungaran, didapatkan bahwa daerah tersebut merupakan daerah prospek panas bumi. Hasil penelitian geofisika dengan metode magnetik didapatkan pengontrol manifestasi panas bumi berupa sesar pada kedalaman 1050 meter – 1100 meter. Suhu reservoir yang diperoleh sebesar 230 <sup>o</sup>C, dimana masuk dalam kategori syarat potensi energi panas bumi. Hasil konversi energi panas bumi  ke listrik sebesar 15 % dari besarnya daya listrik per satuan luas adalah 2,25 MWe. Perkiraan luas prospek panas bumi Gunung Ungaran adalah 1 km<sup>2 </sup>maka daya listrik yang dapat dimanfaatkan adalah 2,25 MWe. Jika di konversi, jumlah daya listrik sebesar 2,25 MWe dapat menerangi rumah sebanyak 2500 rumah jika setiap rumahnya mempunyai daya 900 Watt.</p><p><em>Studies on the potential of geothermal energy and recommendations for its use have been carried out at Mount Ungaran, Central Java, the location of the Gedongsongo temple. The research aims to estimate the potential for geothermal energy at the southern slope of Mount Ungaran, as well as making a scheme for the utilization of geothermal electricity as a recommendation for use in the area. Some of the results of research conducted in the fields of geophysics, geology and geochemistry at Gedongsongo on the southern slope of Mount Ungaran, found that the area is a geothermal prospect area. The results of geophysical research using the magnetic method show that the controller of geothermal manifestations is faults at depths of 1050 meters - 1100 meters. The reservoir temperature obtained is 230 <sup>o</sup>C, which is included in the category of geothermal energy potential requirements. The result of the conversion of geothermal energy to electricity by 15% of the amount of electricity per unit area is 2.25 MWe. The estimated area of Mount Ungaran's geothermal prospect is 1 km<sup>2</sup>, the electric power that can be utilized is 2.25 MWe. If converted, the amount of electric power of 2.25 MWe can illuminate 2500 homes if each house has 900 Watt power.</em></p>

scholarly journals STUDYING OF THE CHANGE OF VEGETABLE COVER OF THE SOUTHERN SLOPE OF GREATER CAUCASUS ON THE BASIS OF SPACE IMAGES

2018 ◽  
Vol 63 (1) ◽  
pp. 107-112 ◽  
Author(s):  
H. H. Asadov ◽  
V. M. Novruzov ◽  
P. M. Efendiyev ◽  
I. M. Nasibov ◽  
R. H. Khalilov ◽  
...  
Keyword(s):  
Southern Slope ◽  
Space Images ◽  
Greater Caucasus

scholarly journals Konfigurasi Cekungan Tomori Berdasarkan Data Gayaberat

2019 ◽  
Vol 20 (1) ◽  
pp. 27
Author(s):  
Tatang Padmawidjaja
Keyword(s):  
Gravity Anomaly ◽  
Oil And Gas ◽  
Sedimentary Rocks ◽  
Bouguer Anomaly ◽  
Reservoir Rock ◽  
Ultramafic Rocks ◽  
Geophysical Research ◽  
Rock Density ◽  
Basin Area ◽  
Subsurface Modeling

Geophysical research in Tomori Basin, Kolonodale Bay using the gravity method was carried out to identified anticline structural trap in associated with hydrocarbon prospect. The occurence of hydrocarbon seepage in some places, indicate that hydrocarbon have been formed although its distribution is not clearly known. The gravity Bouguer anomaly resulted two groups of rock units: the group of 40 mGal up to 120 mGal gravity anomaly represent ultramafic rocks, and group of 30 mGal up to -80 mGal gravity anomaly reflected a sedimentary rocks basin. The subsurface modeling of the rock density can be grouped into three layers: the Cenozoic (2.5-2.55 gr/cm³ density), the Mesozoic (2.6-2.7 gr/cm³ density), and the Basement ( 2.8-2.9 gr/cm³ density). Elongated and vertical closure are reflected by anomaly 0-2 mGal with density 2.5 gr/cm3 to 2:55 mGal which is supposed to be oil and gas structures. The Source rock is characterized by  0  to -10 mGal anomaly  interpreted as oil kitchen at sub-basin area. Location of the reservoir rock is assumed in the Cenozoic layer on Salodik Group with density of 2.5 gr/cm³. The Basement is estimated at depth of 3.5-4 km, derived from the Group of metamorphic and volcanic rocks.Keyword: Gravity, basin, residual anomaly, fault, anticline. DOI:10.33332/jgsm.2019.v20.1.27-36

scholarly journals Neotectonic structure of the Mahe (Seychelles)

2016 ◽  
pp. 20-26
Author(s):  
L. V. Panina ◽  
V. A. Zaitsev
Keyword(s):  
Statistical Processing ◽  
Geological Data ◽  
Space Images ◽  
Instrumental Observations ◽  
Geomorphological Analysis

The carried out complex researches, including structural and geomorphological analysis, statistical processing of the space images interpretation, allowed to reveal block style of the latest structures of the Mahe island and to determine the nature of their relationship fractures in the granite’s outcrops. The results obtained were compared with the geological data and instrumental observations of the modern movements.

scholarly journals Konfigurasi Cekungan Tomori Berdasarkan Data Gayaberat

2019 ◽  
Vol 20 (1) ◽  
pp. 27
Author(s):  
Tatang Padmawidjaja
Keyword(s):  
Gravity Anomaly ◽  
Oil And Gas ◽  
Sedimentary Rocks ◽  
Bouguer Anomaly ◽  
Reservoir Rock ◽  
Ultramafic Rocks ◽  
Geophysical Research ◽  
Rock Density ◽  
Basin Area ◽  
Subsurface Modeling

Geophysical research in Tomori Basin, Kolonodale Bay using the gravity method was carried out to identified anticline structural trap in associated with hydrocarbon prospect. The occurence of hydrocarbon seepage in some places, indicate that hydrocarbon have been formed although its distribution is not clearly known. The gravity Bouguer anomaly resulted two groups of rock units: the group of 40 mGal up to 120 mGal gravity anomaly represent ultramafic rocks, and group of 30 mGal up to -80 mGal gravity anomaly reflected a sedimentary rocks basin. The subsurface modeling of the rock density can be grouped into three layers: the Cenozoic (2.5-2.55 gr/cm³ density), the Mesozoic (2.6-2.7 gr/cm³ density), and the Basement ( 2.8-2.9 gr/cm³ density). Elongated and vertical closure are reflected by anomaly 0-2 mGal with density 2.5 gr/cm3 to 2:55 mGal which is supposed to be oil and gas structures. The Source rock is characterized by  0  to -10 mGal anomaly  interpreted as oil kitchen at sub-basin area. Location of the reservoir rock is assumed in the Cenozoic layer on Salodik Group with density of 2.5 gr/cm³. The Basement is estimated at depth of 3.5-4 km, derived from the Group of metamorphic and volcanic rocks.Keyword: Gravity, basin, residual anomaly, fault, anticline.

scholarly journals Konfigurasi Cekungan Tomori Berdasarkan Data Gayaberat

2019 ◽  
Vol 20 (1) ◽  
pp. 27
Author(s):  
Tatang Padmawidjaja
Keyword(s):  
Gravity Anomaly ◽  
Oil And Gas ◽  
Sedimentary Rocks ◽  
Bouguer Anomaly ◽  
Reservoir Rock ◽  
Ultramafic Rocks ◽  
Geophysical Research ◽  
Rock Density ◽  
Basin Area ◽  
Subsurface Modeling

Geophysical research in Tomori Basin, Kolonodale Bay using the gravity method was carried out to identified anticline structural trap in associated with hydrocarbon prospect. The occurence of hydrocarbon seepage in some places, indicate that hydrocarbon have been formed although its distribution is not clearly known. The gravity Bouguer anomaly resulted two groups of rock units: the group of 40 mGal up to 120 mGal gravity anomaly represent ultramafic rocks, and group of 30 mGal up to -80 mGal gravity anomaly reflected a sedimentary rocks basin. The subsurface modeling of the rock density can be grouped into three layers: the Cenozoic (2.5-2.55 gr/cm³ density), the Mesozoic (2.6-2.7 gr/cm³ density), and the Basement ( 2.8-2.9 gr/cm³ density). Elongated and vertical closure are reflected by anomaly 0-2 mGal with density 2.5 gr/cm3 to 2:55 mGal which is supposed to be oil and gas structures. The Source rock is characterized by  0  to -10 mGal anomaly  interpreted as oil kitchen at sub-basin area. Location of the reservoir rock is assumed in the Cenozoic layer on Salodik Group with density of 2.5 gr/cm³. The Basement is estimated at depth of 3.5-4 km, derived from the Group of metamorphic and volcanic rocks.Keyword: Gravity, basin, residual anomaly, fault, anticline.

scholarly journals Konfigurasi Cekungan Tomori Berdasarkan Data Gayaberat

2019 ◽  
Vol 20 (1) ◽  
pp. 27
Author(s):  
Tatang Padmawidjaja
Keyword(s):  
Gravity Anomaly ◽  
Oil And Gas ◽  
Sedimentary Rocks ◽  
Bouguer Anomaly ◽  
Reservoir Rock ◽  
Ultramafic Rocks ◽  
Geophysical Research ◽  
Rock Density ◽  
Basin Area ◽  
Subsurface Modeling

Geophysical research in Tomori Basin, Kolonodale Bay using the gravity method was carried out to identified anticline structural trap in associated with hydrocarbon prospect. The occurence of hydrocarbon seepage in some places, indicate that hydrocarbon have been formed although its distribution is not clearly known. The gravity Bouguer anomaly resulted two groups of rock units: the group of 40 mGal up to 120 mGal gravity anomaly represent ultramafic rocks, and group of 30 mGal up to -80 mGal gravity anomaly reflected a sedimentary rocks basin. The subsurface modeling of the rock density can be grouped into three layers: the Cenozoic (2.5-2.55 gr/cm³ density), the Mesozoic (2.6-2.7 gr/cm³ density), and the Basement ( 2.8-2.9 gr/cm³ density). Elongated and vertical closure are reflected by anomaly 0-2 mGal with density 2.5 gr/cm3 to 2:55 mGal which is supposed to be oil and gas structures. The Source rock is characterized by  0  to -10 mGal anomaly  interpreted as oil kitchen at sub-basin area. Location of the reservoir rock is assumed in the Cenozoic layer on Salodik Group with density of 2.5 gr/cm³. The Basement is estimated at depth of 3.5-4 km, derived from the Group of metamorphic and volcanic rocks.Keyword: Gravity, basin, residual anomaly, fault, anticline. DOI:10.33332/jgsm.2019.v20.1.27-36

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