Baguio Mineral District: An oceanic arc witness to the geological evolution of northern Luzon, Philippines

Abstract

The Baguio Mineral District exposes rock formations that evince the geological and tectonic evolution of this district from a subduction-related marginal basin to an island arc setting. Available onshore and offshore data are consistent with an Early (onset phase) to Middle (developed phase) Miocene arc polarity reversal from the east (termination of subduction along the proto-East Luzon Trough) to the west (initiation of subduction along the Manila Trench). Geophysical modeling and geochemical data calculation showed a 30 Ϯ 5 km crustal thickness for the mineral district. Subduction-related multiple arc magmatism and ophiolite accretion contributed to crustal thickening. Recent information on the Oligo-Miocene Zigzag and Klondyke formations in the mineral district reveal that the marginal basin, where these rocks were deposited, has received eroded materials from adjacent terrains characterized by siliceous lithologies. Furthermore, adakitic rocks, high permeable zones and extensional zones which are exploration markers applied to identify possible mineralization targets, are prevalent in the mineral district. The geological evolution that the district had undergone mimics the evolution of island arcs worldwide in general and northern Luzon in particular.

Geochemistry and geochronology of intrusive units in the Suyoc epithermal deposit: Constraints on magma fertility in the Mankayan Mineral District, Philippines

“…Meanwhile, the calc-alkaline tonalite-granodiorite of the Bagon Intrusive Complex represents a subduction-related magmatic event in the Late Eocene. The recognition of a Late Eocene intrusive in Mankayan supports tectonic models indicating Eocene subduction along the proto-East Luzon Trench beneath Luzon, which later experienced arc reversal that resulted in subduction at the Manila Trench [15]. The calc-alkaline hornblende quartz diorite represents an adakitic pulse of magmatism in the Pliocene.…”

Unlocking clues on the provenance of the Zigzag Formation in Mountain Province, Northern Luzon, Philippines using sedimentary geochemistry

“…Northern Luzon records magmatic pulses that occurred in the Eocene to Oligocene, resulting from subduction along the proto-East Luzon Trough in the eastern portion of Luzon [8]. In the Central Cordillera, the region is floored by Cretaceous to Eocene ophiolitic rocks formed in a subduction-related marginal basin [8][9][10]. Progressive uplift and erosion of the basement unit resulted in the deposition of Late Oligocene to Early Miocene clastic sequences in a deep marine setting [10].…”

“…In the Central Cordillera, the region is floored by Cretaceous to Eocene ophiolitic rocks formed in a subduction-related marginal basin [8][9][10]. Progressive uplift and erosion of the basement unit resulted in the deposition of Late Oligocene to Early Miocene clastic sequences in a deep marine setting [10]. During the Late Miocene to Middle Miocene, an arc reversal shifted the subduction zone along the Manila Trench to the west [1][3].…”

Interpretation of ground magnetic data in Suyoc, Mankayan Mineral District, Philippines

“…The Luzon Central Cordillera is an uplifted magmatic arc that formed as a result of the Middle Miocene subduction of the South China Sea plate along the Manila Trench. Mineralization in the Cordillera is linked to magmatism along this arc (e.g., Bellon and Yumul Jr., 2000; Yumul Jr. et al ., 2008). The MMD is underlain by an Upper Cretaceous to Eocene basement rocks, Upper Oligocene to Middle Miocene clastic‐volcaniclastic sequence, Pliocene mineralized dacitic rocks, Pleistocene unmineralized dacitic porphyritic rocks and pyroclastic units (e.g., Chang et al ., 2011).…”