Struktur kompleks melange dan asosiasi ofiolitik di dalam formasi Ciletuh Sukabumi-Jawa Barat

Field observations have generated two kinds of data, which is lithological and structural data. The lithological data were used to determine groups of rock. There are two main groups of rock in the field studied, which are Ciletuh Formation and melange. Further more, melange can be divided into three units of rock, namely breccia, serpentine and schist. Besides of the two kinds of data above, An image of Landsat TM has been used to support it. Rationing band 4 to band 3 of Landsat TM have resulted an image expressing a difference between unit of breccia, ophiolitic rock and other units (Ciletuh and Bayah Formation). This phenomenon was usefull to determine a spread of rock. In the other hand, image analyzing of band 5 that have been filtered revealed 5 of general trends of lineament, that are NOE, N40°E, N275°E, N300°E and N325°E.

Structural data analyzing included lineament show that since Lower Eocene-Middle Eocene time have occurred a changing of field stress at least three times in the field studied. Respecting Hindia-Australia plate motion and the old of rock that contents related structure enable us to determine the time of occurring of each field stress. Firstly, during Lower Eocene-Middle Eocene time, the maximum stress trending to N319°E. The stress have generated a N-S strike slip fault and gently dipping thrust faults trending to N68°E. Secondly, during Upper Eocene-Lower Oligocene time, the maximum stress trending to N355°E. The stress have generated N275°E striking thrust faults and a conjugate strike slip faults, that are N325°E strike slip faults and N40°E strike slip faults. stly, the maximum stress trending to N25°E. The stress have generated N-S strike slip faults and N300°E striking thrust faults.

Combining structural data and lithological data have revealed a conclusion that The Ciletuh's Ophiolitic have thrusted two times The first, the ophiolithic rocks have been thrusted southeastward on a plane trending to N68°E. This process occurred in a state of ductile-brittle deformation in 5-10 kms of depth. The second, the ophiolitic rocks have been thrusted southward occurring in a state of brittle deformation in 0-5 kms of depth.

Relationship between Ciletuh Formation, unit of breccia and the ophiolitic rock could be deduced from both measured cross-section and the thrusting ophiolitic processes. The Ciletuh Formation overlying on the unit of breccia conformably and both units Ciletuh Formation and unit of breccia contact to the ophiolitic rock tectonically