MULTILAYER TERRANE MODELS FOR GLOBAL MINERAL RESOURCE ASSESSMENT: A CASE STUDY IN THE NW CIRCUM PACIFIC AND SE ASIA REGIONS

A geodynamic framework was developed for porphyry copper assessments of East Asia from Kamchatka to Indonesia, with a focus on reconstruction of arc systems that unify coeval magmatic belts and accretionary complexes. Unraveling magmatic arcs in accretionary orogens of Paleozoic Central Asia and the Meso-Cenozoic western Circum Pacific region is complex; the latter consist of short-lived arcs, diachronous collisional belts, oroclines, and triple junctions that have all been complicated by structural patterns. The tectonic history from the Cretaceous to the present is illustrated in time slice maps for NE and SE Asia that correspond to the main pulses of arc magmatism, along with basement terrane maps. Major periods of reorganization of NE Asia arc systems are related to (a) docking of the Okhotsk Sea block to the East Asia continental arc at ~80 Ma, (b) arc-continent collisions in Sakhalin and Kamchatka at ~45 Ma, and (c) diachronous docking of the Kronotskiy arc to east Kamchatka at ~30–15 Ma. Cretaceous evolution of the Indonesian region was controlled by a SE Asia continental arc and the Halmahera oceanic arc in the East Philippines. Lack of 70–50 Ma arc magmatism implies that there was no subduction at that time. Initiation of several arcs in the Eocene may reflect global reorganization of lithospheric plates due to onset of the Indostan collision. Since ~50 Ma, the region was dominated by 4 large arc systems: (1) Kalimantan- North Luzon, (2) Sunda-Central Philippines, (3) East Philippines-Halmahera, and (4) Izu-Bonin-Mariana. Diachronous collisions of former arcs with microcontinents and SE Asia and Australian margins produced the complex patterns of present day Indonesia.

Multilayer terrane models facilitate visualization of the tectonic history of the western Circum Pacific region, delineate basement terranes, reconstruct overlapping arcs through time, determine arc polarities, and establish links between accretionary episodes and reorganization of arc systems.