ABSTRACT

MODELING OF SEDIMENT BASIN IN MENGGALA

AND ITS SURROUNDINGS, LAMPUNG PROVINCE

USING GRAVITY DATA

By

KUSDINAR KARTASAPUTRA

H1C003009

Departement of Physics

Universitas Jenderal Soedirman

Geophysical survey was done with gravity method at Menggala and its surroundings, Lampung Province. A gravity meter LaCoste & Romberg type G.525 was used in this survey. Position and time was determined using Global Positioning System (GPS) Garmin, while measurement of elevation used barometer Aneroid Precission and thermometer with looping method. The purpose of this research is to know the shape and distribution of sediment basin. Gravity reduction data include read conversion of gravity meter into milligal value, drift correction, tidal correction, latitude correction, free air correction, Bouguer correction and terrain correction so that Bouguer anomaly is obtained in topography. The result of qualitative interpretation to Bouguer anomaly shows that the increasing of Bouguer anomaly value across north-south or precisely reside in part of southeast is occurred. It means that thickness of sediment decreases. The value is around 26 mGal – 76 mGal. Model of the quantitative interpretation was carried out by using Talwani 2 1/2-D method. From the model result, two type of rock are found. Sediment rock (sandstone, claystone) with density 2.46 gr/cc is found at deepness of 0-3 km and granite composition rock or rock of metamorf as bedrock (granitic or metamorphic basement) with density 2.6 gr/cc is found at deepness of surface vary until around 3 km.

Key Word : Gravity method, Menggala, sediment basin