Abstract
Bouguer gravity anomalies were studied on Ibaragi district near Osaka, Japan, with regards to emplacement structure of granitic complex intruded into the paleozoic sediments. The gravity anomalies observed seemed to finely correspond to the distribution of granitic rocks over the area. Rock facies of the complex are changed from adamellite at the central zone to quartz diorite in the marginal shell, but the most parts of it are coarse-grained granodiorite whose density is considerably smaller than the quartz diorite or paleozoic rocks, and obviously give a negative anomalous zone of gravity in the surveyed area. Gravity anomaly was analytically explained with two or three dimensional models of subsurface structures in which the complex had a light central mass under the southwestern area and extended toward northwest at the deeper horizons. Continuated gravity fields suggest that the Myoken pluton is not isolated in place, but get emplacement near the northern part of the Nose.
