DIVERSITY OF ISLAND ARCS: JAPAN, PHILIPPINES, NORTHERN MOLUCCAS

1973 ◽  
Vol 13 (1) ◽  
pp. 19
Author(s):  
Richard W. Murphy
Keyword(s):  
Late Cretaceous ◽  
Subduction Zones ◽  
The Philippines ◽  
Island Arc ◽  
Late Oligocene ◽  
Island Arcs ◽  
Isostatic Gravity ◽  
Formed Part ◽  
Northeast Asian ◽  
Surface Geology

Modern bathymetric, geophysical, and volcanic studies have revealed a remarkably consistent principal profile for island arcs of the Western Pacific. Examination of surface geology, however, suggests great diversity in the geological development of island arcs. Three island arc complexes show the diversity well: Japan, the Philippines, and the Northern Moluccas.Although Japan appears to have been an island arc in roughly its present configuration only since Early Miocene time, the surface geology indicates that Japan has formed part of the continental margin of Asia at least since Permian and probably Devonian time. Subduction polarity, as displayed in paired metamorphic belts; juxtaposition of continental rise prisms with contemporaneous oceanic suites; and overall tectonic fabric strongly supports belief in the existence of the Pacific Ocean since the Devonian. Hokkaido is a reversed island arc segment which together with Sakhalin is probably a relatively recent addition to the northeast Asian continental perimeter.The Philippines were formed by the Late Oligocene coalescence of at least four island arc-subduction zone complexes into a single archipelagic basin which has remained more or less coherent throughout Neogene time. Although the oldest Philippine fossils are Permian, the island arcs probably did not start to form until Late Cretaceous time. Neogene volcanism, intrusion and sedimentation are thought to be creating a new small continent out of materials that were originally entirely oceanic.Island arc systems flanking the Molucca Sea were born in Late Cretaceous time and now appear to be in a stage of coalescence similar to that of the Philippines in Late Oligocene time. The convergence of two west-dipping and one east-dipping Benioff zones, the existence of a very large negative isostatic gravity anomaly, the outcrop of fossil subduction zones and the existence of short topographic trench segments indicate an active, youthful region of crustal construction.

Subduction-related magmatic imprint of most Philippine ophiolites: implications on the early geodynamic evolution of the Philippine archipelago

2004 ◽  
Vol 175 (5) ◽  
pp. 443-460 ◽  
Author(s):  
Rodolfo A. Tamayo* ◽  
René C. Maury* ◽  
Graciano P. Yumul ◽  
Mireille Polvé ◽  
Joseph Cotten ◽  
...  
Keyword(s):  
Partial Melting ◽  
Subduction Zone ◽  
Volcanic Rocks ◽  
The Philippines ◽  
Island Arc ◽  
Island Arcs ◽  
Geodynamic Evolution ◽  
Wide Range ◽  
Opening And Closing ◽  
Back Arc

Abstract The basement complexes of the Philippine archipelago include at least 20 ophiolites and ophiolitic complexes. These complexes are characterised by volcanic sequences displaying geochemical compositions similar to those observed in MORB, transitional MORB-island arc tholeiites and arc volcanic rocks originating from modern Pacific-type oceans, back-arc basins and island arcs. Ocean island basalt-like rocks are rarely encountered in the volcanic sequences. The gabbros from the ophiolites contain clinopyroxenes and plagioclases showing a wide range of XMg and An values, respectively. Some of these gabbros exhibit mineral chemistries suggesting their derivation from basaltic liquids formed from mantle sources that underwent either high degrees of partial melting or several partial melting episodes. Moreover, some of the gabbros display a crystallization sequence where orthopyroxene and clinopyroxene appeared before plagioclase. The major element compositions of coexisting orthopyroxenes and olivines from the mantle peridotites are consistent with low to high degrees of partial melting. Accessory spinels in these peridotites display a wide range of XCr values as well with some of them above the empirical upper limit of 0.6 often observed in most modern mid-oceanic ridge (MOR) mantle rocks. Co-existing olivines and spinels from the peridotites also exhibit compositions suggesting that they lastly equilibrated under oxidizing mantle conditions. The juxtaposition of volcanic rocks showing affinities with modern MOR and island arc environments suggests that most of the volcanic sequences in Philippine ophiolites formed in subduction-related geodynamic settings. Similarly, their associated gabbros and peridotites display mineralogical characteristics and mineral chemistries consistent with their derivation from modern supra-subduction zone-like environments. Alternatively, these rocks could have, in part, evolved in a supra-subduction zone even though they originated from a MOR-like setting. A simplified scenario regarding the early geodynamic evolution of the Philippines is proposed on the basis of the geochemical signatures of the ophiolites, their ages of formation and the ages and origins of the oceanic basins actually bounding the archipelago, including basins presumed to be now totally consumed. This scenario envisages the early development of the archipelago to be largely dominated by the opening and closing of oceanic basins. Fragments of these basins provided the substratum on top of which the Cretaceous to Recent volcanic arcs of the Philippines were emplaced.

scholarly journals Understanding the Geology of the Philippines through Gravity Anomalies

2021 ◽  
Author(s):  
Mel Anthony Asis Casulla ◽  
Hideki Mizunaga ◽  
Toshiaki Tanaka ◽  
Carla Dimalanta
Keyword(s):  
Gravity Anomaly ◽  
Gravity Anomalies ◽  
Sedimentary Basins ◽  
The Philippines ◽  
Island Arc ◽  
Gravity Gradient ◽  
Mobile Belt ◽  
Upward Continuation ◽  
Basement Rocks ◽  
Isostatic Gravity

Abstract The Philippine Archipelago is a complex island arc system, where many regions still lack geopotential studies. This study aims to present a general discussion of the Philippine gravity anomaly distribution. The high-resolution isostatic anomaly digital grid from the World Gravity Map (WGM) was processed and correlated with the Philippines’ established geology and tectonics. This study also investigated the gravity signatures that correspond to the regional features, e.g., geology, structures, sedimentary basins, and basement rocks of the study area. Upward continuation, high-pass, and gradient filters (i.e., first vertical derivative, horizontal gradient) were applied using the Geosoft Oasis Montaj software. The interpreted gravity maps’ results highlighted the known geologic features (e.g., trench manifestation, ophiolite distribution, basin thickness). They revealed new gravity anomalies with tectonic significance (e.g., basement characterization). The isostatic gravity anomaly map delineates the negative zones. These zones represent the thick sedimentary accumulations along the trenches surrounding the Philippine Mobile Belt (PMB). The Philippine island arc system is characterized by different gravity anomaly signatures, which signify the density contrast of subsurface geology. The negative anomalies (< 0 mGal) represent the thick sedimentary basins, and the moderate signatures (0 to 80 mGal) correspond to the metamorphic belts. The distinct very high gravity anomalies (> 80 mGal) typify the ophiolitic basement rocks. The gravity data’s upward continuation revealed contrasting deep gravity signatures; the central Philippines of continental affinity (20 – 35 mGal) was distinguished from the remaining regions of oceanic affinity (45 – 200 mGal). Local geologic features (e.g., limestone, ophiolitic rocks) and structures (e.g., North Bohol Fault, East Bohol Fault) were also delineated downward continuation and gravity gradient maps of Bohol Island. The WGM dataset’s effectiveness for geologic investigation was achieved by comparing the established geologic features and interpreted gravity anomalies. The processed gravity digital grids provided an efficient and innovative way of investigating the Philippines’ regional geology and tectonics.

Deportation of “Undesirable” Chinese in the Philippines, 1837–1882

2021 ◽  
Vol 15 (2) ◽  
pp. 214-246
Author(s):  
Jely Agamao Galang
Keyword(s):  
Nineteenth Century ◽  
Labor Supply ◽  
The Philippines ◽  
The State ◽  
Spanish Empire ◽  
Spanish Colonial ◽  
Formed Part ◽  
Colonial Government ◽  
Primary Materials

Abstract Between 1837 and 1882, the Spanish colonial government in the Philippines deported “undesirable” Chinese—vagrants, drunkards, unemployed, idlers, pickpockets, undocumented, and the “suspicious”—to various parts of the archipelago. Deportation, in this context, refers to the transportation or banishment of individuals deemed “dangerous” by the state to different far-flung areas of the islands or outside the colony but still within the Spanish empire. Deportation primarily served as a form of punishment and a means to rehabilitate and improve the wayward lives of “criminals.” This paper examines the deportation of “undesirable” Chinese in the nineteenth-century Philippines. Using underutilized primary materials from various archives in Manila and Madrid, it interrogates the actors, institutions and processes involved in banishing such individuals. It argues that while deportation served its punitive and reformative functions, Spanish authorities also used it to advance their colonial project in the islands. Chinese deportees formed part of the labor supply the state used to populate the colony’s frontier areas and strengthen its control over its newly-acquired territories.

scholarly journals Breeding Temperate Japonica Rice Varieties Adaptable to Tropical Regions: Progress and Prospects

Agronomy ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2253
Author(s):  
Myrish Pacleb ◽  
O-Young Jeong ◽  
Jeom-Sig Lee ◽  
Thelma Padolina ◽  
Rustum Braceros ◽  
...  
Keyword(s):  
The Philippines ◽  
Tropical Region ◽  
Japonica Rice ◽  
Rice Varieties ◽  
Temperate Japonica ◽  
Tropical Regions ◽  
Tropical Environments ◽  
Increasing Demand ◽  
Northeast Asian ◽  
The Tropics

Temperate japonica rice is mainly cultivated in temperate regions. Many temperate japonica varieties have a superior grain quality that is preferred in Northeast Asian countries such as Japan, Korea, and China. The changes in consumers’ preferences in Southeast Asia and Western countries has contributed to increasing the demand for temperate japonica. Most temperate japonica varieties developed in temperate regions typically exhibit extra-early flowering under the short-day conditions in the tropics, which usually results in severely reduced yields. Since 1992, we have been developing temperate japonica varieties that can adapt to tropical environments to meet the increasing demand for temperate japonica rice, having released six varieties in the Philippines. Especially, the yield of one of the temperate japonica varieties, Japonica 7, was comparable to the yields of leading indica varieties in the Philippines. Here, we discuss the current breeding initiatives and future plans for the development of tropical-region-bred temperate japonica rice.

scholarly journals Tectonic reconstruction of Uda-Murgal arc and the Late Jurassic and Early Cretaceous convergent margin of Northeast Asia–Northwest Pacific

2009 ◽  
Vol 4 ◽  
pp. 273-288 ◽  
Author(s):  
S. D. Sokolov ◽  
G. Ye. Bondarenko ◽  
A. K. Khudoley ◽  
O. L. Morozov ◽  
M. V. Luchitskaya ◽  
...  
Keyword(s):  
Northeast Asia ◽  
Upper Jurassic ◽  
Island Arc ◽  
Passive Margin ◽  
Northwest Pacific ◽  
Island Arcs ◽  
The South ◽  
Convergent Margin ◽  
Tectonic Zone ◽  
The North

Abstract. A long tectonic zone composed of Upper Jurassic to Lower Cretaceous volcanic and sedimentary rocks is recognized along the Asian continent margin from the Mongol-Okhotsk fold and thrust belt on the south to the Chukotka Peninsula on the north. This belt represents the Uda-Murgal arc, which was developed along the convergent margin between Northeast Asia and Northwest Meso-Pacific. Several segments are identified in this arc based upon the volcanic and sedimentary rock assemblages, their respective compositions and basement structures. The southern and central parts of the Uda-Murgal arc were a continental margin belt with heterogeneous basement represented by metamorphic rocks of the Siberian craton, the Verkhoyansk terrigenous complex of Siberian passive margin and the Koni-Taigonos Late Paleozoic to Early Mesozoic island arc with accreted oceanic terranes. At the present day latitude of the Pekulney and Chukotka segments there was an ensimatic island arc with relicts of the South Anyui oceanic basin in a backarc basin. Accretionary prisms of the Uda-Murgal arc and accreted terranes contain fragments of Permian, Triassic to Jurassic and Jurassic to Cretaceous (Tithonian–Valanginian) oceanic crust and Jurassic ensimatic island arcs. Paleomagnetic and faunal data show significant displacement of these oceanic complexes and the terranes of the Taigonos Peninsula were originally parts of the Izanagi oceanic plate.

Seismic Structure and Tectonic Evolution of Borneo and Sulawesi

2021 ◽  
Author(s):  
Harry Telajan Linang ◽  
Amy Gilligan ◽  
Jennifer Jenkins ◽  
Tim Greenfield ◽  
Felix Tongkul ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Receiver Function ◽  
Leading Edge ◽  
Sedimentary Basins ◽  
Crustal Thickness ◽  
The Philippines ◽  
Seismic Structure ◽  
Eurasian Plate ◽  
Seismic Stations ◽  
Preliminary Results

&lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;p&gt;Borneo is located at the centre of Southeast Asia, which is one of the most active tectonic regions on Earth due to the subduction of the Indo-Australian plate in the south and the Philippines Sea plate in the east. Borneo resides on the leading edge of the Sundaland block of the Eurasian plate and exhibits lower rates of seismicity when compared to the surrounding regions due to its intraplate setting. Sulawesi, an island which lies just southeast of Borneo, is characterised by intense seismicity due to multiple subduction zones in its vicinity. The tectonic relationship between the two islands is poorly understood, including the provenance of their respective lithospheres, which may have Eurasian and/or East Gondwana origin.&lt;/p&gt; &lt;p&gt;Here, we present recent receiver function (RF) results from temporary and permanent broadband seismic stations in the region, which can be used to help improve our understanding of the crust and mantle lithosphere beneath Borneo and Sulawesi. We applied H-K stacking, receiver function migration and inversion to obtain reliable estimates of the crustal thickness beneath the seismic stations. Our preliminary results indicate that the crust beneath Sabah (in northern Borneo), which is a post-subduction setting, appears to be much more complex and is overall thicker (more than 35 km) than the rest of the island. In addition, we find that crustal thickness varies between different tectonic blocks defined from previous surface mapping, with the thinnest crust (23 to 25 km) occurring beneath Sarawak in the west-northwest as well as in the east of Kalimantan.&lt;/p&gt; &lt;p&gt;We also present preliminary results from Virtual Deep Seismic Sounding (VDSS) in northern Borneo, where from the RF results we know that there is thick and complex crust. VDSS is able to produce well constrained crustal thickness results in regions where the RF analysis has difficulty recovering the Moho, likely due to complexities such as thick sedimentary basins and obducted ophiolite sequences.&lt;/p&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt;

Geology, petrology and tectonomagmatic evolution of the plutonic crustal rocks of the Sabzevar ophiolite, NE Iran

2013 ◽  
Vol 150 (5) ◽  
pp. 862-884 ◽  
Author(s):  
MORTEZA KHALATBARI JAFARI ◽  
HASSAN A. BABAIE ◽  
MOJTABA MIRZAIE
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Island Arc ◽  
Magma Chambers ◽  
Northern Margin ◽  
Crustal Rocks ◽  
Microscopic Studies ◽  
Element Enrichment ◽  
Spider Diagrams ◽  
Ocean Ridge

AbstractThe plutonic crustal sequence exposed northeast of Sabzevar is part of the ophiolitic belt of Sabzevar that occurs along the northern margin of the Central Iran micro-continent. The sequence includes olivine and pyroxene gabbro with cumulate characteristics, isotropic gabbro, foliated gabbro and a diabase sheeted dyke complex cut by wehrlite and olivine websterite intrusions, and pegmatite gabbro and plagiogranite as small intrusions and dykes. The sequence is comparable to gabbros in known ophiolite complexes. Microscopic studies show an abundance of the mesocumulate and heteradcumulate textures that represent open system magma chambers, which are common in supra-subduction zones. The olivine → plagioclase → clinopyroxene → ± orthopyroxene → amphibole trend of mineralization in the gabbros, similar to mid-ocean ridge basalt (MORB), and olivine → clinopyroxene → ± orthopyroxene → plagioclase → amphibole, similar to arc rocks, indicate the diversity in the formation of these rocks, and represent petrographic evidence of their formation in a supra-subduction zone. The rocks have calc-alkaline to tholeiitic affinities, and niobium depletion in the spider diagrams of diabase that matches the patterns of island arc magma. These patterns, and the light rare earth element enrichment of the diabase and plagiogranite, suggest the effect and introduction of the fluids, originating from the subducting slab, beneath the mantle wedge. The low titanium compositions, matching those of arc diabase and plagiogranite, plot in the island arc to MORB tectonomagmatic fields, and suggest formation of the Sabzevar ophiolitic plutonic crustal sequence in a supra-subduction zone during Late Cretaceous time.

scholarly journals Tectonic denudation of a Late Cretaceous–Tertiary collisional belt: regionally symmetric cooling patterns and their relation to extensional faults in the Anatolide belt of western Turkey

2003 ◽  
Vol 140 (4) ◽  
pp. 421-441 ◽  
Author(s):  
UWE RING ◽  
CHRISTOPHER JOHNSON ◽  
RALF HETZEL ◽  
KLAUS GESSNER
Keyword(s):  
Late Cretaceous ◽  
Metamorphic Core Complex ◽  
Early Miocene ◽  
Second Phase ◽  
Late Oligocene ◽  
Core Complex ◽  
Cooling History ◽  
Western Turkey ◽  
Structural Levels ◽  
Metamorphic Core

Thermochronological data reveal that the Late Cretaceous–Tertiary nappe pile of the Anatolide belt of western Turkey displays a two-stage cooling history. Three crustal segments differing in structure and cooling history have been identified. The Central Menderes metamorphic core complex represents an ‘inner’ axial segment of the Anatolide belt and exposes the lowest structural levels of the nappe pile, whereas the two ‘outer’ submassifs, the Gördes submassif to the north and the Çine submassif to the south, represent higher levels of the nappe pile. A regionally significant phase of cooling in the Late Oligocene and Early Miocene affected the outer two submassifs and the upper structural levels of the Central Menderes metamorphic core complex. In the northern part of the Gördes submassif, cooling was related to top-to-the-NNE movement on the Simav detachment, as the apatite fission-track ages show a northward-younging trend in the direction of movement on this detachment. In the Çine submassif, relatively rapid cooling in Late Oligocene and Early Miocene times may have been related to top-to-the-S extensional reactivation of the basal thrust of the overlying Lycian nappes. The second phase of cooling in the Anatolide belt is related to Pliocene to Recent extension resulting in the formation of the Central Menderes metamorphic core complex in the inner part of the Anatolide belt. Core-complex development caused the formation of supra-detachment graben, which document the ongoing separation of the Central Menderes metamorphic core complex from the outer submassifs.

Lithogeochemistry of volcano-plutonic assemblages of the southern Hanson Lake Block and southeastern Glennie Domain, Trans-Hudson Orogen: evidence for a single island arc complex

1999 ◽  
Vol 36 (2) ◽  
pp. 209-225 ◽  
Author(s):  
Ralf O Maxeiner ◽  
Tom II Sibbald ◽  
William L Slimmon ◽  
Larry M Heaman ◽  
Brian R Watters
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Oceanic Island ◽  
Island Arc ◽  
Island Arcs ◽  
Calc Alkaline ◽  
East Central ◽  
South Central ◽  
Volcaniclastic Rocks ◽  
Flin Flon

This paper describes the geology, geochemistry, and age of two amphibolite facies volcano-plutonic assemblages in the southern Hanson Lake Block and southeastern Glennie Domain of the Paleoproterozoic Trans-Hudson Orogen of east-central Saskatchewan. The Hanson Lake assemblage comprises a mixed suite of subaqueous to subaerial dacitic to rhyolitic (ca. 1875 Ma) and intercalated minor mafic volcanic rocks, overlain by greywackes. Similarly with modern oceanic island arcs, the Hanson Lake assemblage shows evolution from primitive arc tholeiites to evolved calc-alkaline arc rocks. It is intruded by younger subvolcanic alkaline porphyries (ca. 1861 Ma), synvolcanic granitic plutons (ca. 1873 Ma), and the younger Hanson Lake Pluton (ca. 1844 Ma). Rocks of the Northern Lights assemblage are stratigraphically equivalent to the lower portion of the Hanson Lake assemblage and comprise tholeiitic arc pillowed mafic flows and felsic to intermediate volcaniclastic rocks and greywackes, which can be traced as far west as Wapawekka Lake in the south-central part of the Glennie Domain. The Hanson Lake volcanic belt, comprising the Northern Lights and Hanson Lake assemblages, shows strong lithological, geochemical, and geochronological similarities to lithotectonic assemblages of the Flin Flon Domain (Amisk Collage), suggesting that all of these areas may have been part of a more or less continuous island arc complex, extending from Snow Lake to Flin Flon, across the Sturgeon-Weir shear zone into the Hanson Lake Block and across the Tabbernor fault zone into the Glennie Domain.

Sign in / Sign up

Export Citation Format

Share Document