Many scientists used the power spectrum of the gravity anomaly to obtain the average depth of the disturbing surface or equivalently the average depth to the top of the disturbing body. The spectrum of gravity anomaly...Many scientists used the power spectrum of the gravity anomaly to obtain the average depth of the disturbing surface or equivalently the average depth to the top of the disturbing body. The spectrum of gravity anomaly due to layered source is separated into multiple segments in frequency domain that can be interpreted in terms of mean depth of the interface. The half of the slope of the segments gives the mean depth of the interfaces. This study aims to estimate the average residual depth anomalies of various regions of the northern Logone Birni sedimentary basin of Cameroon using polynomial separation of gravity anomalies, and spectral analysis along different profiles (segments). The profiles were derived from residual anomaly maps obtained by fitting the Bouguer anomalies, the interpretation used polynomial separation and depth average was done using spectral analysis. Positive and negative residual gravity anomalies were highlighted and their interpretation revealed the structural directions of the sedimentary basin (NW-SE and NE-SW), as well as an intimate relationship between the negative anomalies and the northern Logone Birni sedimentary basin. Three distinct residual anomalies were identified over the Goulfey, Tom Merifine and Tourba basin with an average depth varying between 0.24 km and 4.55 km.展开更多
Detecting the anomalies’ sources location in the vast territory such as Kouremale area is a grand challenge for geophysicists because there is a need to assess gold deposit. Therefore, this paper aims to recommend a ...Detecting the anomalies’ sources location in the vast territory such as Kouremale area is a grand challenge for geophysicists because there is a need to assess gold deposit. Therefore, this paper aims to recommend a methodological approach on applied magnetic survey and soil geochemistry to identify the location of anomalies’ sources. To that aim the study is divided into phases. In the first phase, the maps for integrated interpretation have been produced by Geosoft Oasis and ArcGIS 10.2.1. The corrected and processed magnetic data with eliminated diurnal variation have been used. Phase two consist of integrate geochemical soil map. The results of phase one identified four magnetic anomalies zones (MAZ) with their coordinates. Thus, the obtained radiometric map, showed that there is a high intensity of K and Th compared to U, which indicates a significant weathering process and there are many saprolithes in study area. The findings of phase two revealed that there is a high concentration of gold content (1500 ppm) with an average concentration of 92 ppm. The integrated interpretation map coming from the combined different maps, referring to the geological information verified on the field, led to conclude that, the target B is the best gold anomaly. The delimitation of the space of the target B from the geophysical and geochemical information confirmed the existence of limited, restricted and potential anomaly.展开更多
The gravity and magnetic survey lines of about 13,500 km were carried out in the centraland northern parts of the South China Sea from 1977 to 1978. The results obtained showthat the Bouguer gravity and magnetic anoma...The gravity and magnetic survey lines of about 13,500 km were carried out in the centraland northern parts of the South China Sea from 1977 to 1978. The results obtained showthat the Bouguer gravity and magnetic anomalies have a tendency to increase gradually theirvalues from the northern continental shelf, through the slope, to the central abyssal basin of theSouth China Sea. The change in free-air gravity anomaly values coincides to a certain degreewith the undulation of the sea-bottom topography. The primary factor determining regionalvariation of the Bouguer gravity anomayl values is the Moho depth. The main factor deter-mining the magnetic anomly values is the nature of the basement rock. The high magnetieand Bouguer gravity anomaly values observed in some fault basin areas are inferred to becaused by draping the basic and ultrabasic magma extruding along the faults on the basementof the metamorphic rock,or by intrusion of the same magma into the basement.展开更多
文摘Many scientists used the power spectrum of the gravity anomaly to obtain the average depth of the disturbing surface or equivalently the average depth to the top of the disturbing body. The spectrum of gravity anomaly due to layered source is separated into multiple segments in frequency domain that can be interpreted in terms of mean depth of the interface. The half of the slope of the segments gives the mean depth of the interfaces. This study aims to estimate the average residual depth anomalies of various regions of the northern Logone Birni sedimentary basin of Cameroon using polynomial separation of gravity anomalies, and spectral analysis along different profiles (segments). The profiles were derived from residual anomaly maps obtained by fitting the Bouguer anomalies, the interpretation used polynomial separation and depth average was done using spectral analysis. Positive and negative residual gravity anomalies were highlighted and their interpretation revealed the structural directions of the sedimentary basin (NW-SE and NE-SW), as well as an intimate relationship between the negative anomalies and the northern Logone Birni sedimentary basin. Three distinct residual anomalies were identified over the Goulfey, Tom Merifine and Tourba basin with an average depth varying between 0.24 km and 4.55 km.
文摘Detecting the anomalies’ sources location in the vast territory such as Kouremale area is a grand challenge for geophysicists because there is a need to assess gold deposit. Therefore, this paper aims to recommend a methodological approach on applied magnetic survey and soil geochemistry to identify the location of anomalies’ sources. To that aim the study is divided into phases. In the first phase, the maps for integrated interpretation have been produced by Geosoft Oasis and ArcGIS 10.2.1. The corrected and processed magnetic data with eliminated diurnal variation have been used. Phase two consist of integrate geochemical soil map. The results of phase one identified four magnetic anomalies zones (MAZ) with their coordinates. Thus, the obtained radiometric map, showed that there is a high intensity of K and Th compared to U, which indicates a significant weathering process and there are many saprolithes in study area. The findings of phase two revealed that there is a high concentration of gold content (1500 ppm) with an average concentration of 92 ppm. The integrated interpretation map coming from the combined different maps, referring to the geological information verified on the field, led to conclude that, the target B is the best gold anomaly. The delimitation of the space of the target B from the geophysical and geochemical information confirmed the existence of limited, restricted and potential anomaly.
文摘The gravity and magnetic survey lines of about 13,500 km were carried out in the centraland northern parts of the South China Sea from 1977 to 1978. The results obtained showthat the Bouguer gravity and magnetic anomalies have a tendency to increase gradually theirvalues from the northern continental shelf, through the slope, to the central abyssal basin of theSouth China Sea. The change in free-air gravity anomaly values coincides to a certain degreewith the undulation of the sea-bottom topography. The primary factor determining regionalvariation of the Bouguer gravity anomayl values is the Moho depth. The main factor deter-mining the magnetic anomly values is the nature of the basement rock. The high magnetieand Bouguer gravity anomaly values observed in some fault basin areas are inferred to becaused by draping the basic and ultrabasic magma extruding along the faults on the basementof the metamorphic rock,or by intrusion of the same magma into the basement.
