Geophysical Studies of the Highbury Meteorite Impact Structure, Zimbabwe

The 20-1cm-diameter Highbury meteorite impact structure in northern Zimbabwe, centred on 30°<br>06’55’ ‘E, 17° 03 ‘53” S, is developed in Paleoproterozoic metasedimentary country rocks of the c.<br>2.0-1.8 Ga Magondi Belt [1,2) (Fig. 1). The undeformed Munwa Granophyre, believed to be an<br>impact melt-rock, intrusive info shocked, brecciated country rocks, hos a zirco U-Pb age of 1034±1 3<br>Ma (21. Ground gravity, magnetic, and resistivity studies of the Highbury structures were carried out<br>in 1995 [3). The gravity study indicates a central high (with a large offset anomaly coinciding with<br>the granophyre) surrounded by concentric gravity lows. This is interpreted to be the result of a<br>central! uplift cored by denser material from the underlying Chinhoyi greenstone belt. Magnetic<br>studies show that a prominent magnetic anomaly is centred on the Munwa Granophyre, while other<br>anomalies are due to dipping mafic dykes. Resistivity studies show the limited extend of the Munwa<br>Granophyre, and support its interpretation as a downwardly injected impact melt.