NEW CONSIDERATION ON THE CRETACEOUS SUBDUCTION ZONE OF CILETUH-LUK ULO-BAYAT-MERATUS: IMPLICATIONS FOR SOUTHEAST SUNDALAND PETROLEUM GEOLOGY

摘要

The history of plate convergence in southern andrnsoutheastern Sundaland recorded subduction ofrnoceanic plate during Jurassic to Late Cretaceousrnstarted from Meratus, Bantimala, Luk Ulo, tornCiletuh. The geochronology of subduction is basedrnon subduction-related high pressure to ultra/veryrnhigh pressure glaucophane schists and eclogites.rnSubduction chased in Bantimala and Meratusrntrenches in mid-Cretaceous due to docking of WestrnSulawesi and Paternoster-Kangean microcontinents,rnrespectively. During the Late Cretaceous,rnsubduction migrated to Paternoster trench resultingrnin volcanic and magmatic rocks as well as forearcrnsediments in Meratus and Bantimala. In Paleogenerntime, Meratus and Bantimala separated by thernopening of the Makassar Straits, sitting onrnPaternoster and West Sulawesi microcontinents.rnSubduction in Ciletuh and Luk Ulo continued intornthe Late Cretaceous, but possibly with differentrncharacters of subduction compared to that of EarlyrnCretaceous due to the absence of Late Cretaceousrnsubduction-related metamorphic rocks. Jiwo Hills,rnBayat which has been considered as therncontinuation of Luk Ulo, is considered not torncompose the subduction zone due to the absence ofrnsubduction-related rock assemblage. The mid-rnCretaceous glaucophane schist of Bayat may relaternwith docking of SE Java microcontinent in this area.rnEocene shallow marine Wungkal-Gampingrncarbonate shows that Bayat is different with LukrnUlo and Ciletuh which in Eocene wererncharacterized by slope trench olistostromal depositsrnof Karangsambung and Ciletuh Formations,rnrespectively.rnConfiguration of plate convergence during thernCretaceous implies petroleum possibilities ofrnsoutheastern Sundaland related to the presence ofrnsome Australian-origin microcontinents. Newlyrnacquired deep seismic data in south offshorernEast Java, eastern East Java Sea, and South Makassar Straits show the presence of Mesozoic-rnPaleozoic bedded horizons typical NW Shelf ofrnAustralia which are proven to be productive or otherrnproven prolific Australoid microcontinents likernBintuni, Seram, or Buton. Pre-Tertiary petroleumrnsystem may develop in southeastern Sundaland.