Abstract:
Data on the subsurface geography is critical as it partners varieties in the density and rock types.
Gravimetric technology describes the best geological features related to natural hazards, natural
resources and tectonic events in the upper Earth’s crust to a depth of about 20 km. Compared
to most geophysical techniques, gravimetric data acquisition, processing and interpretation are
simple and inexpensive. A particularly interesting aspect of gravimetric technology is that the
applied instrumentation and the methods of interpretation are largely independent of the scale
of examination, so that this technique can be used in various applications. Bouguer anomaly is
commonly used by applied geophysicists. The Bouguer anomaly reflects lateral variations in
the interior of the Earth. The knowledge of Bouguer anomaly can therefore be used to determine
the size and shape of the geological feature that causes it. However, there is no unique model
of causative agent for heterogeneity. This is because gravity modelling has an inherent uncertainty. However, knowing the geology of the region and other relevant information can reduce
this uncertainty to a reasonable level. The major lithotectonic units of Sri Lanka’s Precambrian
are Wanni Complex (WC), Highland Complex (HC) and Vijayan Complex (VC). In addition,
several other minor units can be identified. All of these lithotectonic units formed by a variety
of rock types and show different densities with respect to them. But the boundary between these
units is not properly identified. This research focuses to study about the boundary using gravity
data. There is a significant Bouguer anomaly variation on either side of the boundary between
the complexes. It indicates that there is a gravity variation, otherwise density variation, in the
area while delivering an idea of the nature of the complexes. When comparing gravity survey
data and modelled data, Gravity survey data can therefore reveal more accurate information.
