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
Gravity and magnetic data were analyzed in conjunction with available geological data to determine the origin of observed positive gravity anomaly at Waza and its possible relationship to mafic intrusions. The data an...Gravity and magnetic data were analyzed in conjunction with available geological data to determine the origin of observed positive gravity anomaly at Waza and its possible relationship to mafic intrusions. The data analysis includes the construction of a Bouguer gravity anomaly, isostatic residual gravity anomaly, total magnetic gradient and Euler solutions maps, and two and one-half dimensional gravity models. A positive gravity anomaly that occurs in Waza has amplitude of 35 mGal and can be separated into two parts. The top of the disturbing body causing the anomaly cannot be deeper than 4 km. We believe the anomaly is probably caused by a body of basaltic rocks lying at the upper surface of the Precambrian basement and originate from a self-propagating disturbance of magmatic loads on a pre-existing zone of lithospheric weakness. Melt migration might have been aided by tectonic and flexural stresses, such that the intrusion is limited in extent to the melting region of the plume and did not reach the surface. The model calculated to satisfy the observed anomaly consists of a 2.5 Km-thick slab underlain by a 10.5 km deep column. This model is interpreted to represent a sheet or saucer-like mafic intrusion that has a thick deep feeder. Detailed geophysical studies would be necessary to locate any possible economic occurrences.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Gravity and magnetic data were analyzed in conjunction with available geological data to determine the origin of observed positive gravity anomaly at Waza and its possible relationship to mafic intrusions. The data analysis includes the construction of a Bouguer gravity anomaly, isostatic residual gravity anomaly, total magnetic gradient and Euler solutions maps, and two and one-half dimensional gravity models. A positive gravity anomaly that occurs in Waza has amplitude of 35 mGal and can be separated into two parts. The top of the disturbing body causing the anomaly cannot be deeper than 4 km. We believe the anomaly is probably caused by a body of basaltic rocks lying at the upper surface of the Precambrian basement and originate from a self-propagating disturbance of magmatic loads on a pre-existing zone of lithospheric weakness. Melt migration might have been aided by tectonic and flexural stresses, such that the intrusion is limited in extent to the melting region of the plume and did not reach the surface. The model calculated to satisfy the observed anomaly consists of a 2.5 Km-thick slab underlain by a 10.5 km deep column. This model is interpreted to represent a sheet or saucer-like mafic intrusion that has a thick deep feeder. Detailed geophysical studies would be necessary to locate any possible economic occurrences.
