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Regional tectonic setting of the Philippines (data from openly sourced General Bathymetric Chart of the Oceans (GEBCO), 2019 Grid dataset).
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Tectonic reconstruction models of Southeast Asia all invoke in the early Cenozoic the collision of Mesozoic oceanic plates, which have been fragmented, consumed along subduction zones or emplaced onto the overriding plate. However, with marked variations in these models, we reinvestigate the tectonic evolutionary landscape of Southeast Asia through...
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... Philippine archipelago has been the locus of plate interaction between various plates. The present-day tectonics of the arc involves the convergence between the South China Sea of the Sunda Plate, and the West Philippine Basin of the Philippine Sea Plate (Fig. 1). While the setting is seemingly easy to comprehend, a different perspective can be said about the Philippine arc's early evolution. More recent plate reconstruction models based on regional geology, computer-based reconstructions, mantle tomography and slab unfolding suggest involvement of the proto-Philippine Sea, the proto-South ...
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... this work, the Bangui Formation was observed in several localities in Cagayan and Ilocos Norte. The base of the formation consists of interbeds of green sandstones and red siltstones that conformably overlie the pillow basalts ( Fig. 5A1-A2). This is best observed along the coast of Claveria, Cagayan. The sandstone beds are a few centimeters to a meter-thick. Most of the sandstones grade normally to siltstones and are parallel and/or convolute laminated. On the other hand, the pillow basalts are commonly porphyritic and amygdaloidal. They extend for about 200 m along the ...
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... higher stratigraphic levels, the formation is dominated by polymictic conglomerates that are best exposed in Ilocos Norte ( Fig. 5B1-B2). Most of the conglomerates are massive with a maximum thickness of 100 m. The conglomerates contain pebble-to cobble-sized andesitic to basaltic clasts and minor red siliceous mudstones embedded in a tuffaceous, sandy matrix. Occasionally, the conglomerates are associated with sandstone and siltstone interbeds. Along the national road ...
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... Pandan Formation is best observed in eastern-central Cebu where the stratigraphic unit is well-exposed. The approximately 150-m thick succession includes interbedded sandstone and siltstone and normally graded conglomerates (Fig. 10A-B). The interbedded sandstone-siltstone makes up the lower part of the succession. This consists of moderately weathered, interbedded gray fine-grained sandstone and gray to greenish siltstone. The sandstone beds (~0.02-0.5 m) are often thicker than the siltstone beds (0.01-0.2 m). Some sandstone beds contain parallel lamination and/or ...
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... formation of marginal basins now surrounding the archipelago (e.g. Mitchell et al., 1986;Faure et al., 1989;Encarnacion et al. 1993;Dimalanta and Yumul, 2006;Queaño et al., 2008). Mapping of these units suggests that these are mainly products of submarine mass transport processes that commonly involve turbidity currents, slumping and debris flows (Fig. 11). The stacking and repetition of the different facies (e.g., channelized and unchannelized facies) clearly reflect multiple depositional events that are consequential to the arc's interaction with plates now consumed under the Philippine arc and the rest of SE Asia. Lateral juxtaposition of similar facies (e.g., channel-fill sequences) ...
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... This would have an important implication on their basinal sources and plate affinity (see Section 5.2). As in the case of the Caraballo Formation in the NSM and the Bangui Formation in the northern portion of the Luzon Central Cordillera, these deposits are associated with pillow basalts that represent the early stages of island arc development (Fig. 11). The geochemistry of the pillow basalts from the two formations reflecting similar arc affinity for these rocks provides additional evidence (Fig. ...
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... et al., 2020). Regardless of how we should call this Mesozoic plate, the development of the West Philippine Basin within this Mesozoic plate, coupled with oblique subduction along the Philippine arc, should account for the tectonic features (accreted Mesozoic ophiolites along the Philippine arc; Eocene arc rocks) that we see in this region (Fig. 12). Previous workers (Karig, 1983;Pubellier et al., 2004) suggested that oblique subduction of the bounding plates has been affecting the Philippine arc throughout much of its Cenozoic history. This event induced strain partitioning and development of wrench faulting which also provided a mechanism for the docking of ophiolite in eastern ...
Citations
... According to our tomographic model, we infer that the detachment of the Pacific slab occurred in two stages (Figures 6i-6k, 7a-7h, and 10). At the first stage, the detached Pacific slab lied beneath the West Philippine Basin between 15° and 25°N (Figures 6i-6k and 7a-7h), concordant with the paleolatitudinal location of the Shikoku and Parece-Vela basins when they initiated at ∼30 Ma (Sdrolias et al., 2004) as suggested by reconstruction models (e.g., Queaño et al., 2020;Wu et al., 2016). At the second stage, the detached Pacific slab was suited between 16° and 20°N under the northern Mariana Trough (Figures 6i-6k and 7a-7h). ...
Formation and evolution of the Philippine Sea Plate (PSP) are still highly debated, mainly because the PSP has been surrounded by subduction zones since its inception. Therefore, it is vital to determine a new tomographic model with higher resolution to precisely portray the subducted slabs beneath and around the PSP, in particular, the subducted Pacific slab that has played an essential role in the PSP formation and evolution. In this study, an updated tomographic model is obtained by inverting a large number of P‐wave arrival times of local and regional earthquakes in and around the PSP. Our tomography reveals a detached piece of the Pacific slab in the mantle transition zone beneath the middle PSP, which may be mainly related to the PSP clockwise rotation and transform or strike‐slip faults in this region. The detached Pacific slab may promote the formation and evolution of the Shikoku and Parece‐Vela basins and the Mariana Trough by inducing hot mantle upwelling. Our tomography also reveals isolated high‐velocity anomalies beneath the southernmost PSP, which may reflect remnants of the subducted slab at the beginning of the PSP formation. A high‐velocity gap appears beneath the southern PSP, which may reflect the influence of a mantle plume.
... It is possible that the subducted slab composition was preserved in the Eocene volcaniclastics (i.e., Caraballo and its Eocene equivalents). Previous studies found that these units were the result of the magmatism in Luzon during the Early Cenozoic (e.g., [21,22]). Also, the sharp contrast between the data trends suggests that a different subducted slab must have influenced the Acoje. ...
The Angat Ophiolitic Complex, located north-northeast of Manila, Luzon is perhaps one of Luzon’s most fundamental suspect terranes. The definite age of the ophiolite is not well-established, with various authors having different claims. Encarnacion et al. (1993) conducted a U-Pb age dating for the Angat wherein the Angat Ophiolite was found to have an Early Middle Eocene age (48 Ma), close to the ZOC age - leading to the assumption that the two ophiolites are related and underlie most of Central Luzon. Hence, this paper aims to collect samples from the Eocene and Cretaceous Angat Ophiolite for petrographic and geochemical analyses, identify the relationship between the separated basalt units from the basalts in the main ophiolite body, and compare the geochemistry of the Eocene and Cretaceous units of the Angat Ophiolite with the other well-known ophiolites from the literature. Field investigations were conducted in five important localities wherein 15 samples were obtained. The results highlighted that the major mineral phases in the samples collected are plagioclase and augite, with some samples having hornblende and olivine. All samples appear to have undergone low-grade greenschist facies metamorphism, which may be attributed to hydrothermal alteration. Chloritization of pyroxene minerals is also evident, along with the hydrothermal alteration products of plagioclase and pyroxenes. The relationship between the EAO, MOC, and separated basalt patch in Marilaque Highway is identified. The Coto Block of the Zambales Ophiolite and the Angat Ophiolite may be related and formed over a mantle initially enriched by a subduction component.
... Uranium-lead (U-Pb) dating of olivine gabbro and syenite floats yielded a minimum age of Early Cretaceous (Heuret and Lallemand 2005). The extents of tectonic features are from Queaño et al. (2020). (b) Geologic map of the CPO modified from MMAJ-JICA (1990), Aurelio et al. (2014), and Dycoco et al. (2021). ...
... However, results of our model indicate that the two basins were once connected due to their similar formation ages and basement composition, but the connection initiated 10 Myrs earlier based on the plate motion trajectory (Figure 2). This is more consistent with the study illustrating the initial overlapping spreading time and the geographical affinity at ∼30 Ma of two basins (Queaño et al., 2020). ...
Insight into the evolution of Philippine Sea‐South China Sea (SCS) plate motions helps reveal the driving mechanisms of the long‐term tectonic complexity in Southeast Asia. Here, based on the integration of the most recent geological and seismic data, we present a new plate reconstruction model for this region characterized by back‐arc extension and subduction since the Eocene. We suggest that the western boundary of the Philippine Sea Plate was a constant sinistral strike‐slip fault at 55–22 Ma with a clockwise self‐rotation. The connection between the SCS and Shikoku Ridges possibly initiates at 30 Ma, when their spreading times overlapped indicating an affinitive origin and magma source. Regional‐scale geodynamic simulations interfaced with our reconstructed plate motion indicate that the seismic high‐velocity body under the SCS is likely to be the leading edge of the Pacific Slab.
... The Philippine Sea Plate is uniquely located among the Eurasian, Pacific, and Indo-Australian plates, and is of great importance to fundamental plate tectonic theory and global tectonic evolution (Hall, 2002;Reagan et al., 2010;Wu et al., 2016;Maunder et al., 2020;Sibuet et al., 2021). The Philippine Sea Plate is not only a natural laboratory for the study of plate tectonics on aspects of initial subduction, arc rifting, and back-arc spreading (Reagan et al., 2010;Arculus et al., 2015;Maunder et al., 2020;Chen et al., 2021;Li et al., 2021) but is also significant for the tectonic reconstruction of the West Pacific and East Asia (Hall, 2002;Zahirovic et al., 2014;Lallemand, 2016;Wu et al., 2016;Ma et al., 2019;Queaño et al., 2020;Liu et al., 2021;Sibuet et al., 2021). ...
The Ocean Drilling Program Site 1177 recovered the oldest (∼23 Ma) sedimentary records in the Shikoku Basin, northeastern part of the Philippine Sea Plate. Changes in sediment provenances bear important implications for the tectonic evolution of the Philippine Sea Plate, but existing data are still controversial for the early Miocene. By integrating Sr-Nd isotopes, rock-magnetic parameters, diffuse reflectance spectroscopy, and the previous data on the detrital zircons and clay minerals from Site 1177, we found that a significant provenance shift occurred at ∼16.5 Ma. The sediments of Site 1177 before ∼16.5 Ma were mainly sourced from the Pearl River and Izu-Bonin Arc, but changed to the Yangtze River and Izu-Bonin Arc sources after that. This provenance shift was strongly linked with the northward motion and clockwise rotation of the Shikoku Basin in the Miocene, which marked the final time of separation between the Shikoku Basin and the South China Sea.
... However, recent data constrained from zircon grains extracted from xenoliths of the Cansi Volcanics and younger volcano-plutonic units in central Cebu suggests that these zircons were derived from the Eastern Indochina (Gong et al., 2021). Related studies regarding the overlying Late Cretaceous Pandan Formation also imply initiation of Cebu Island arc in a continental margin setting (e.g., oceanic leading edge of the Australian plate margin) (Rodrigo et al., 2020;Queaño et al., 2020). ...
... However, these two models did not involve in the geographical affinity between the SCS and the Eastern PSP. Recently, Queaño et al. (2020) implicitly suggested that the SCS and the eastern PSP were geographically close to each other at ∼30 Ma but did not consider the possible dynamic linkage between the SCS and the eastern PSP. ...
The Philippine Sea Plate (PSP) and the South China Sea (SCS), located at the intersection of the Eurasian, Pacific, and Indo-Australian plates, are key areas for global plate reconstruction. However, the relationships between the PSP and the SCS are still elusive. Here we report a new paleolatitude determination (16.0° ± 4.5°N at ~20 Ma) from the Ocean Drilling Program (ODP) Site 1177 in the Shikoku Basin (SB) within the eastern PSP. The new results indicate that the SB had a geographical affinity with the SCS in the early Miocene. Furthermore, the similarity in the U-Pb zircon age spectra of early Miocene turbidites from SB Site 1177 and SCS Site X28 implies that the two sites might receive similar materials in the early Miocene. Based on the new paleolatitude, provenance results, and other constraints, we suggest that the eastern PSP might be coupled dynamically to the SCS in the early Miocene.
Southeast Asia has great potential for mineral exploration, and this region is well-known to host huge economic ore deposits located in complex tectonic terranes. Amongst these ore deposits, the Ni(Co) laterite deposits are mainly distributed in Indonesia, the Philippines, and Myanmar. There are two main types of Ni(Co) laterite deposits consisting of hydrous Mg silicate (or garnierite) and oxide ores, with limited development of clay silicate type. These deposits are influenced and controlled by the lithology of ultramafic bedrock, topography, climate, weathering, structures, and tectonic environment. The degree of bedrock serpentinization has an important influence on the grade of Ni laterite ore. Given the growing demand of modern society for Ni(Co) ore resources, deep research should be focused on a better understanding of the genesis of this laterite deposit and geological features of Ni(Co) ore, as well as its exploration applications in southeastern Asia. Improving current research and exploration methods by means of cutting-edge technologies can enhance the understanding of the Ni(Co) enrichment mechanism in weathered laterite and lead to the discovery of new deposits in Southeast Asia. Ni(Co) laterite deposits from this region, especially Indonesia and the Philippines, have the potential to be a source of scandium, rare earth elements, and platinum group elements.
The plate tectonic history of the Junction Region, which separated the Panthalassa and Tethys
realms, is notoriously challenging to reconstruct. The region has been dominated by intraoceanic
subduction zones, which has led to a sparsely preserved geological record because not
only the down-going plates but also the overriding plates were lost to subduction. Even though
most lithosphere that was present in the Junction Region during the Mesozoic has been lost to
subduction, orogenic records preserve sparse geological data that provide information for a
plate tectonic reconstruction. Here we present a kinematic reconstruction of the Junction
Region back to the Jurassic, based on the present-day geological record of the circum-Philippine
Sea Plate and Australasian regions, and sparse paleomagnetic data. We provide a
comprehensive review of orogenic and oceanic architecture from Japan to the SW Pacific region
and use a systematic reconstruction protocol for a plate kinematic restoration back to the
Jurassic. Based on our reconstruction, we propose that the Molucca Sea Plate formed as an
Eocene back-arc basin behind a north-dipping subduction zone that consumed Australian
oceanic lithosphere. We find that the Jurassic oceanic lithosphere preserved in the Philippines
originated from the northern Australian margin when a back-arc basin formed. By placing our
reconstruction in mantle reference frames, we identify multiple cases of slab dragging and
suggest that the lithospheric collapse that led to Izu-Bonin Mariana forearc extension may have
been a trigger for the absolute plate motion change of the Pacific Plate that formed the Hawaii-
Emperor Bend. Finally, we show that there is no need for spontaneous subduction initiation at
the Izu-Bonin Mariana trench. Instead, subduction initiation was more likely forced through a
change in Pacific-Australia relative plate motion around 62 Ma. Subduction started along a preexisting
Mesozoic subduction zone that had accommodated mostly transform motion since
about 85 Ma.
The occurrence of long wavelength Moho undulations in continental and oceanic lithospheres is attributed to lithospheric buckling. This has been reported for Cretaceous or older lithospheres under compressional regimes. However, there is very limited data on lithospheric buckling of oceanic island arcs. The region where the Cretaceous Cebu arc is under compression due to the impingement of the Palawan micro-Continental Block (PCB) to the Philippine Mobile Belt (PMB). The configuration of the inferred buckled Cretaceous Cebu arc lithosphere is derived from geologic and combined onshore and airborne gravity and magnetics datasets. Subsurface modeling using gravity data revealed the presence of mantle upwelling beneath Central Cebu. This could be considered as one of the crests of long-wavelength Moho undulations commonly attributed to a buckled lithosphere. The oceanic basement was also modelled to determine its configuration. Euler solutions derived from magnetic data showed that the contact between the arc crustal units of the Cansi Volcanics and Pandan Formation is affected by short wavelength folding with wavelengths ranging from 5 to 15 km. The younger arc crustal units are affected by tighter folding with wavelengths ranging from 1 to 5 km. The occurrence of a buckled arc lithosphere is being considered for the first time in this area. The consistent NE-SW folding axes inferred for the folding events strongly suggest that these are consequences of the Middle Miocene collision involving the Philippine Mobile Belt and the Palawan micro-Continental Block.
