Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
... Fusion de la croute oceanique dans les zones de subduction/collision recentes; l'exemple... more ... Fusion de la croute oceanique dans les zones de subduction/collision recentes; l'exemple deMindanao (Philippines). Rene C. Maury, Fernando G. Sajona, Manuel Pubellier, Herve Bellon, and Marc J. Defant Univ. Bretagne Occident., Dep. Sci. Terre, Brest, France. ...
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Leg 124 of the Ocean Drilling Project drilled Sites 767 and 770 in the northern Celebes Sea, reac... more Leg 124 of the Ocean Drilling Project drilled Sites 767 and 770 in the northern Celebes Sea, reaching late middle Eocene basaltic basement at both sites. Major shifts in sediment provenance record the changing tectonic setting of the basin. From late middle Eocene into early Miocene time pelagic sedimentation prevailed, with little influence from continental or volcanic arc sources. A major continental influence is first documented in middle Miocene time as a thick sequence of quartzose, mud-rich turbidites accumulated on the deeper basin floor, possibly in response to middle Miocene orogeny in northern Borneo. Terrigenous turbidite deposition waned during the late Miocene as active arc volcanism began to contribute significant amounts of hemipelagic sediment and ash layers, which have remained the dominant basinal sediment to the present. Although the Celebes Sea is now nearly surrounded by volcanic arc terranes, the absence of volcaniclastic sediment in the Eocene to early Miocene section suggests that the basin did not form by back-arc spreading.
Holes were drilled at three Sites in the Sulu Sea on Ocean Drilling Program Leg 124. Site 768 lie... more Holes were drilled at three Sites in the Sulu Sea on Ocean Drilling Program Leg 124. Site 768 lies in the deeper part of the SE sub-basin and Sites 769 and 771 lie on the flanks of the Cagayan ridge. The results indicate that the Sulu Basin originated in the late early Miocene (c.18.8 Ma) in a backarc setting. The Cagayan Ridge was a site of early to early middle Miocene arc volcanism with the deposition of a thick sequence of andesitic to basaltic volcaniclastic deposits. In the basin center an early Miocene pelagic sequence is interrupted by a thick unit of rhyolitic to dacitic pyroclastic flows. Middle to late Miocene sedimentation is more continental in character with thick quartz-rich turbidites in the basin center. Only the hemipelagic claystone related to these terrigenous turbidites were deposited on the Cagayan Ridge. A decrease in the supply of clastic detritus from arc and continental sources and a change in the level of the carbonate compensation depth in the upper Pliocene resulted in pelagic carbonate deposition throughout the late Pliocene and Pleistocene.
Central Mindanao was the locus of a Pliocene (45 Ma old) arc-arc collision event followed by bas... more Central Mindanao was the locus of a Pliocene (45 Ma old) arc-arc collision event followed by basaltic to dacitic magmatism starting at 2.3 Ma, representing the most voluminous volcanic field in the Philippines. Lava compositions range from calc-alkaline to shoshonitic ...
Abstract Mindanao, the largest island in the southern Philippine archipelago, is a composite of a... more Abstract Mindanao, the largest island in the southern Philippine archipelago, is a composite of at least two terranes; one with Eurasian affinity (western Mindanao) and the other belonging to the Philippine Mobile Belt (eastern Mindanao), of Philippine Sea plate affinity ...
... Claveria (1998, 2001) on the other hand, identified two episodes of sulfide mineraliza-tion s... more ... Claveria (1998, 2001) on the other hand, identified two episodes of sulfide mineraliza-tion separated by a brecciation event. ... From one wall rock, a zone of discretely banded miner-als consisting of early crystalline sulfides (sphalerite±gale-na±chalcopyrite) deposited directly ...
Abstract The PliocenePleistocene magmatic activity of the Zamboanga are is linked to the southwa... more Abstract The PliocenePleistocene magmatic activity of the Zamboanga are is linked to the southward subduction of the OligoceneMio-cene Sulu Sea back-are basin along the Sulu Trench. The magmatic products include small amounts of adakites dated from 3.8 to 0.7 ...
... Fernando G. Sajona * , , Hervé Bellon , René C. Maury , Manuel Pubellier , Ramon D. Q... more ... Fernando G. Sajona * , , Hervé Bellon , René C. Maury , Manuel Pubellier , Ramon D. Quebral * , , Joseph Cotten , Francis Edward Bayon § , Ericson ... In: DE Hayes, Editor, The Tectonic and Geologic Evolution of Southeast Asian Seas and Islands, AGU Monograph 23 ...
... Table 1. Geochemical analyses of adakites, NEB and NEBA from Philippines. ... Th, U, Ta, Zr a... more ... Table 1. Geochemical analyses of adakites, NEB and NEBA from Philippines. ... Th, U, Ta, Zr and Hf have been obtained by INAA (CEN Saclay). NEB, Nb-enriched basalts; NEBA; Nb-enriched basaltic andesites. Major elements measured as wt%, trace elements in ppm. ...
ABSTRACT Abstract Two new cases of association of adakites with ‘normal’ island arc lavas and tra... more ABSTRACT Abstract Two new cases of association of adakites with ‘normal’ island arc lavas and transitional adakites are recognized in the islands of Batan and Negros in northern and central Philippines, respectively. The Batan lavas are related to the subduction of the middle Miocene portion of the South China Sea basin along the Manila trench; those of Negros come from the almost aseismic subduction of the middle Miocene Sulu Sea crust along the Negros trench. The occurrence of the Batan adakites is consistent with previous findings showing adakitic glass inclusions within minerals of mantle xenoliths associated with Batan arc lavas. The similarity of adakite ages (1.09 Ma) and that of the metasomatized xenoliths (1 Ma) suggests that both are linked to the same slab-melting and metasomatic event. Earlier Sr, Pb and Nd-isotopic studies, however, also reveal the presence of an important sediment contribution to the Batan lava geochemistry. Thus, the role played by slab melts, assumed to have mid-ocean ridge basalts-like (MORB) isotopic characteristics, in enriching the Batan subarc mantle is largely masked by the sediment input. The Negros adakites are present only in Mount Cuernos, the volcanic center nearest to the Negros trench. Batch partial melting calculations show that the Negros adakites could be derived from a garnet amphibolitic source with normal-MORB (N-MORB) geochemistry. This is supported by the MORB-like isotopic characteristics of the Mount Cuernos lavas. The volcanic rocks from the other volcanoes consist of normal arc and transitional adakitic lavas that have slightly higher Sr- and Pb-isotopic ratios, probably due to slight sediment input. Mixing of adakites and normal arc lavas to produce transitional adakites is only partly supported by trace element geochemistry and not by field evidence. The transitional adakites can be modeled as partial melts of an adakite-enriched mantle. Trace element enrichment of non-adakitic lavas could reflect the interaction of their mantle source with uprising slab melts, as metasomatic mantle minerals scavenge certain trace elements from the adakitic fluids. Therefore, in arcs beneath which thick (up to 2 km) continent-derived detrital sediments are involved in subduction, like in Batan, the sediment signature can overwhelm the slab melt input. In arcs like Negros where slow subduction could cause a more efficient scraping of thinner (approximately 1 km) detrital sediments, the contribution of slab melts is easier to detect.
... Hidetoshi Shibuya. Department of Earth Sciences, University of Osaka Prefecture, Sakai, Japan... more ... Hidetoshi Shibuya. Department of Earth Sciences, University of Osaka Prefecture, Sakai, Japan. Jih‐Ping Shyu. Department of Oceanography, Texas A&M University. Renato U. Solidum. Philippine Institute of Volcanology and Seismology, Quezon City, Philippines. Piera Spadea ...
Holes were drilled at three Sites in the Sulu Sea on Ocean Drilling Program Leg 124. Site 768 lie... more Holes were drilled at three Sites in the Sulu Sea on Ocean Drilling Program Leg 124. Site 768 lies in the deeper part of the SE sub-basin and Sites 769 and 771 lie on the flanks of the Cagayan ridge. The results indicate that the Sulu Basin originated in the late early Miocene (c.18.8 Ma) in a backarc setting. The
Initiation of subduction and the generation of slab melts in western and eastern Mindanao, Philip... more Initiation of subduction and the generation of slab melts in western and eastern Mindanao, Philippines Unité de Recherche Associée 1278, Université de Bretagne Occidentale, BP 452, 29275 Brest, France Fernando G. Sajona René C. Maury Hervé Bellon Joseph Cotten Marc ...
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
... Fusion de la croute oceanique dans les zones de subduction/collision recentes; l'exemple... more ... Fusion de la croute oceanique dans les zones de subduction/collision recentes; l'exemple deMindanao (Philippines). Rene C. Maury, Fernando G. Sajona, Manuel Pubellier, Herve Bellon, and Marc J. Defant Univ. Bretagne Occident., Dep. Sci. Terre, Brest, France. ...
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Leg 124 of the Ocean Drilling Project drilled Sites 767 and 770 in the northern Celebes Sea, reac... more Leg 124 of the Ocean Drilling Project drilled Sites 767 and 770 in the northern Celebes Sea, reaching late middle Eocene basaltic basement at both sites. Major shifts in sediment provenance record the changing tectonic setting of the basin. From late middle Eocene into early Miocene time pelagic sedimentation prevailed, with little influence from continental or volcanic arc sources. A major continental influence is first documented in middle Miocene time as a thick sequence of quartzose, mud-rich turbidites accumulated on the deeper basin floor, possibly in response to middle Miocene orogeny in northern Borneo. Terrigenous turbidite deposition waned during the late Miocene as active arc volcanism began to contribute significant amounts of hemipelagic sediment and ash layers, which have remained the dominant basinal sediment to the present. Although the Celebes Sea is now nearly surrounded by volcanic arc terranes, the absence of volcaniclastic sediment in the Eocene to early Miocene section suggests that the basin did not form by back-arc spreading.
Holes were drilled at three Sites in the Sulu Sea on Ocean Drilling Program Leg 124. Site 768 lie... more Holes were drilled at three Sites in the Sulu Sea on Ocean Drilling Program Leg 124. Site 768 lies in the deeper part of the SE sub-basin and Sites 769 and 771 lie on the flanks of the Cagayan ridge. The results indicate that the Sulu Basin originated in the late early Miocene (c.18.8 Ma) in a backarc setting. The Cagayan Ridge was a site of early to early middle Miocene arc volcanism with the deposition of a thick sequence of andesitic to basaltic volcaniclastic deposits. In the basin center an early Miocene pelagic sequence is interrupted by a thick unit of rhyolitic to dacitic pyroclastic flows. Middle to late Miocene sedimentation is more continental in character with thick quartz-rich turbidites in the basin center. Only the hemipelagic claystone related to these terrigenous turbidites were deposited on the Cagayan Ridge. A decrease in the supply of clastic detritus from arc and continental sources and a change in the level of the carbonate compensation depth in the upper Pliocene resulted in pelagic carbonate deposition throughout the late Pliocene and Pleistocene.
Central Mindanao was the locus of a Pliocene (45 Ma old) arc-arc collision event followed by bas... more Central Mindanao was the locus of a Pliocene (45 Ma old) arc-arc collision event followed by basaltic to dacitic magmatism starting at 2.3 Ma, representing the most voluminous volcanic field in the Philippines. Lava compositions range from calc-alkaline to shoshonitic ...
Abstract Mindanao, the largest island in the southern Philippine archipelago, is a composite of a... more Abstract Mindanao, the largest island in the southern Philippine archipelago, is a composite of at least two terranes; one with Eurasian affinity (western Mindanao) and the other belonging to the Philippine Mobile Belt (eastern Mindanao), of Philippine Sea plate affinity ...
... Claveria (1998, 2001) on the other hand, identified two episodes of sulfide mineraliza-tion s... more ... Claveria (1998, 2001) on the other hand, identified two episodes of sulfide mineraliza-tion separated by a brecciation event. ... From one wall rock, a zone of discretely banded miner-als consisting of early crystalline sulfides (sphalerite±gale-na±chalcopyrite) deposited directly ...
Abstract The PliocenePleistocene magmatic activity of the Zamboanga are is linked to the southwa... more Abstract The PliocenePleistocene magmatic activity of the Zamboanga are is linked to the southward subduction of the OligoceneMio-cene Sulu Sea back-are basin along the Sulu Trench. The magmatic products include small amounts of adakites dated from 3.8 to 0.7 ...
... Fernando G. Sajona * , , Hervé Bellon , René C. Maury , Manuel Pubellier , Ramon D. Q... more ... Fernando G. Sajona * , , Hervé Bellon , René C. Maury , Manuel Pubellier , Ramon D. Quebral * , , Joseph Cotten , Francis Edward Bayon § , Ericson ... In: DE Hayes, Editor, The Tectonic and Geologic Evolution of Southeast Asian Seas and Islands, AGU Monograph 23 ...
... Table 1. Geochemical analyses of adakites, NEB and NEBA from Philippines. ... Th, U, Ta, Zr a... more ... Table 1. Geochemical analyses of adakites, NEB and NEBA from Philippines. ... Th, U, Ta, Zr and Hf have been obtained by INAA (CEN Saclay). NEB, Nb-enriched basalts; NEBA; Nb-enriched basaltic andesites. Major elements measured as wt%, trace elements in ppm. ...
ABSTRACT Abstract Two new cases of association of adakites with ‘normal’ island arc lavas and tra... more ABSTRACT Abstract Two new cases of association of adakites with ‘normal’ island arc lavas and transitional adakites are recognized in the islands of Batan and Negros in northern and central Philippines, respectively. The Batan lavas are related to the subduction of the middle Miocene portion of the South China Sea basin along the Manila trench; those of Negros come from the almost aseismic subduction of the middle Miocene Sulu Sea crust along the Negros trench. The occurrence of the Batan adakites is consistent with previous findings showing adakitic glass inclusions within minerals of mantle xenoliths associated with Batan arc lavas. The similarity of adakite ages (1.09 Ma) and that of the metasomatized xenoliths (1 Ma) suggests that both are linked to the same slab-melting and metasomatic event. Earlier Sr, Pb and Nd-isotopic studies, however, also reveal the presence of an important sediment contribution to the Batan lava geochemistry. Thus, the role played by slab melts, assumed to have mid-ocean ridge basalts-like (MORB) isotopic characteristics, in enriching the Batan subarc mantle is largely masked by the sediment input. The Negros adakites are present only in Mount Cuernos, the volcanic center nearest to the Negros trench. Batch partial melting calculations show that the Negros adakites could be derived from a garnet amphibolitic source with normal-MORB (N-MORB) geochemistry. This is supported by the MORB-like isotopic characteristics of the Mount Cuernos lavas. The volcanic rocks from the other volcanoes consist of normal arc and transitional adakitic lavas that have slightly higher Sr- and Pb-isotopic ratios, probably due to slight sediment input. Mixing of adakites and normal arc lavas to produce transitional adakites is only partly supported by trace element geochemistry and not by field evidence. The transitional adakites can be modeled as partial melts of an adakite-enriched mantle. Trace element enrichment of non-adakitic lavas could reflect the interaction of their mantle source with uprising slab melts, as metasomatic mantle minerals scavenge certain trace elements from the adakitic fluids. Therefore, in arcs beneath which thick (up to 2 km) continent-derived detrital sediments are involved in subduction, like in Batan, the sediment signature can overwhelm the slab melt input. In arcs like Negros where slow subduction could cause a more efficient scraping of thinner (approximately 1 km) detrital sediments, the contribution of slab melts is easier to detect.
... Hidetoshi Shibuya. Department of Earth Sciences, University of Osaka Prefecture, Sakai, Japan... more ... Hidetoshi Shibuya. Department of Earth Sciences, University of Osaka Prefecture, Sakai, Japan. Jih‐Ping Shyu. Department of Oceanography, Texas A&M University. Renato U. Solidum. Philippine Institute of Volcanology and Seismology, Quezon City, Philippines. Piera Spadea ...
Holes were drilled at three Sites in the Sulu Sea on Ocean Drilling Program Leg 124. Site 768 lie... more Holes were drilled at three Sites in the Sulu Sea on Ocean Drilling Program Leg 124. Site 768 lies in the deeper part of the SE sub-basin and Sites 769 and 771 lie on the flanks of the Cagayan ridge. The results indicate that the Sulu Basin originated in the late early Miocene (c.18.8 Ma) in a backarc setting. The
Initiation of subduction and the generation of slab melts in western and eastern Mindanao, Philip... more Initiation of subduction and the generation of slab melts in western and eastern Mindanao, Philippines Unité de Recherche Associée 1278, Université de Bretagne Occidentale, BP 452, 29275 Brest, France Fernando G. Sajona René C. Maury Hervé Bellon Joseph Cotten Marc ...
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