A. Ates et P. Kearey, A NEW METHOD FOR DETERMINING MAGNETIZATION DIRECTION FROM GRAVITY ANDMAGNETIC-ANOMALIES - APPLICATION TO THE DEEP-STRUCTURE OF THE WORCESTER GRABEN, Journal of the Geological Society, 152, 1995, pp. 561-566
The aeromagnetic field over the Worcester Graben, a major N-S-oriented
, fault-bounded sedimentary basin, shows a large positive anomaly of 1
00 nT amplitude near the town of Tetbury. A new method for the determi
nation of the magnetization direction of the causative body was employ
ed that searches for the maximum correlation between the observed grav
ity anomaly and the pseudogravity anomaly computed for a range of orie
ntations of the magnetization vector. The method suggests a vertical m
agnetization for the causative body of the Tetbury anomaly. A three-di
mensional magnetic model of the body has the form of a cone, elongated
N-S, whose base is at 6.0 km and upper surface at 3.1 km as indicated
by power spectrum analysis of the anomaly. A two-dimensional model de
rived from the gravity field and constrained by the surface geology, b
orehole data and existing density measurements cannot simulate the obs
erved anomaly over the centre of the graben. However, when the magneti
c body is included in the gravity model, the fit is much improved. The
western side of the body is probably imaged on a seismic reflection p
rofile to the north. The body magnetic model of the body has the form
of a cone, elongated N-S, whose base is at 6.0 km and upper surface at
3.1 km as indicated by power spectrum analysis of the anomaly. A two-
dimensional (sic)