Batan Island Research Articles

Origin of fine-grained peridotite xenoliths from Iraya volcano of Batan Island, Philippines: deserpentinization or metasomatism at the wedge mantle beneath an incipient arc?

Origin of fine-grained peridotite xenoliths from Iraya volcano of Batan Island, Philippines: deserpentinization or metasomatism at the wedge mantle beneath an incipient arc?

Primitive CaO‐rich, silica‐undersaturated melts in island arcs: Evidence for the involvement of clinopyroxene‐rich lithologies in the petrogenesis of arc magmas

On the basis of the study of olivine‐hosted melt inclusions in a calc‐alkaline basalt from Batan Island (Philippines) we define a distinctive type of primitive, nepheline‐normative island arc magma characterized by unusually high CaO contents (up to 19.0 wt %) that cannot be simply explained by melting of the metasomatized peridotitic mantle wedge above subducting oceanic lithosphere. CaO‐rich melt inclusions with these characteristics are preserved in Fo85–90 olivine, and compositional variations among the inclusions are interpreted to reflect mixing between melts such as those found in the most CaO‐rich inclusions (present in Fo90 olivine) and melts similar to primitive “normal” island arc magmas (trapped in Fo85 olivine). Compilation of primitive island arc magmas from the literature shows that whole rocks and olivine‐hosted melt inclusions with CaO contents >13 wt % are found in many arc volcanoes from all over the world in addition to Batan. These inclusions occur in lavas ranging from CaO‐rich ankaramites to basaltic andesites with low‐CaO contents (i.e., <13 wt %). The globally occurring CaO‐rich inclusions and whole rocks comprise a group that although defined on the basis of their CaO contents is compositionally distinctive when compared to island arc lavas that have lower CaO contents; for example, they have lower FeO at a given SiO2 content than most arc lavas, and they are all nepheline normative, with normative nepheline contents positively correlated with CaO contents. Variations in CaO content and normative compositions of experimental partial melts of lherzolite related to changes of pressure, temperature, and source composition suggest that there are no conditions under which partial melting of peridotite can generate melts having CaO contents and other properties comparable to those observed for the primitive, CaO‐rich arc‐derived melts identified here. Although melting of peridotite at high pressure in the presence of CO2 can produce CaO‐rich, silica‐poor liquids, we consider it unlikely that this is responsible for producing the CaO‐rich, silica‐undersaturated melts considered in this study because there are significant differences in nearly all other compositional characteristics between the CaO‐rich arc magmas and melts known or thought to be produced by melting of carbonated peridotite. Model major element compositions of partial melts of clinopyroxene‐rich lithologies (mantle pyroxenites, lower crustal pyroxenites, and eclogites) calculated using the MELTS algorithm suggest that the most CaO‐rich, nepheline‐normative melt inclusions and whole rocks identified here could represent intermediate to high degree (∼10–40 wt %) partial melts of pyroxenites at lower crustal to upper mantle pressures. Such a hypothesis is supported by the comparison between the trace element compositions of model pyroxenite sources of the Batan CaO‐rich melt inclusions and naturally occurring pyroxenites. The most likely source of the primitive CaO‐rich, silica‐undersaturated arc melts identified here is lower crustal and shallow upper mantle pyroxene‐rich cumulates from arc environments because these cumulates have CaO concentrations at the upper end of the range observed for mantle pyroxenites. They are therefore more likely to yield partial melts with the restricted range of remarkably high CaO contents of the most CaO‐rich inclusions and whole rocks identified here. Moreover, these cumulates often contain amphibole, which would lower their solidus temperatures relative to the anhydrous pyroxenite equivalents to values more consistent with those expected in deep crustal or shallow subarc environments.

A new specics ofLycodonfrom the Philippines, with a key to the genus (Reptilia Serpentes Colubridae)

A new species of Lycodon, L. ferroni, from Samar Island, central-eastern Philippines, is described. This species is most similar to L. dumerili, from which it differs in having: 10 supralabials (IV-VI entering eye) instead of 9 (IV-V); dorsals reducing to 15 at the level of ventral 119 instead of at ventrals 131–145; body and tail with dark annuii instead of dark cross-bands. Lycodon contains about 25 species, 8 of which are endemic to the Philippines: alcalai (Batan Island, Batan Group), bibonius (Camiguin Island, Babuyan Group), chrysoprateros (Dalupiri Island, Babuyan Group), dumerili (Basilan, Mindanao), ferroni (Samar), muelleri (Batan, Luzon, Mindoro, Polillo), solivagus (Luzon), and tessellatus (Luzon); the 2 non-endemic species, L. subcinctus (SE Asia) and especially L. aulicus (S Asia), seem to be anthropophilous and likely to have reached the Philippines through human agency. An extensive review strongly suggests that L. striatus nordicus Deranivagala 1955 is a synonym of L. striatus bicolor (Ni...

Transfer of sulfur in subduction settings: an example from Batan Island (Luzon volcanic arc, Philippines)

Sulfur abundances have been determined in silicic and basaltic melt inclusions in olivines from harzburgitic xenoliths and a basaltic lava sample, all from Batan Island. In mantle xenoliths, olivines (Fo 80–91) are present as neoblasts or in finely recrystallized patches. The most magnesian olivines (Fo 89.7–91, CaO < 0.1 wt%) contain primary silicic melt inclusions (SiO 2 = 63.5–60 wt%) with high sulfur concentrations (1440–2540 ppm S), associated with MSS (Monosulfide Solide Solution) globules. The occurrence of both S-rich silicic melts saturated with respect to sulfur, at fO 2 close to Ni–NiO buffer, and multiphase fluid inclusions composed of an S–H 2O-rich vapor phase, a sulfide globule and casual anhydrite strongly suggests high fS 2. The melt and the composite inclusions are interpreted as resulting from the immiscibility between hydrous S-rich silicic melt, sulfide melt, and H 2O–S rich vapor. The S-rich fluid inclusions also indicate the possible existence of an exsolved fluid phase containing sulfur at depth. The moderately silicic melt inclusions (SiO 2 = 62–56.6 wt%) in the Fe-rich olivine (Fo 88.6–80) are depleted with respect to sulfur (S = 430 to 790 ppm), the concentration of which is controlled by the vapor phase. Because the silicic melt inclusions have been previously interpreted as produced by variable extent of melting of the subducted oceanic crust, sulfur in the silicic melts, in the sulfide globules and in the H 2O-rich phase, should therefore be inherited and recycled from the subducted slab through S–H 2O-silicate rich fluids or supercritical fluids (or melts). In the calc-alkaline basalt sample, the olivine phenocrysts (Fo > 85, CaO = 0.25 wt%) and their melt inclusions (CaO/Al 2O 3 from 0.8 to 1.15) have recorded early stages of crystallization. The sulfur concentrations for these calc-alkaline basaltic melts are estimated between 1720 and 3200 ppm, with a mean value at 2550 ppm (1 σ=390) and S/Cl ratio at nearly 1. This is in agreement with the idea that arc basaltic melts may contain high concentrations of sulfur (S > 2000 ppm), at 1200°C. However, the heterogeneous distribution of S and its partitioning between silicate melts, H 2O-rich vapor and S-bearing solid phases as illustrated by the Batan mantle xenoliths would result in highly variable sulfur concentrations in island arc basaltic magmas, mostly controlled by fO 2 and fS 2.

Petrology and geochemistry of Camiguin Island, southern Philippines: insights to the source of adakites and other lavas in a complex arc setting

Camiguin is a small volcanic island located 12 km north of Mindanao Island in southern Philippines. The island consists of four volcanic centers which have erupted basaltic to rhyolitic calcalkaline lavas during the last ∼400 ka. Major element, trace element and Sr, Nd and Pb isotopic data indicate that the volcanic centers have produced a single lava series from a common mantle source. Modeling results indicate that Camiguin lavas were produced by periodic injection of a parental magma into shallow magma chambers allowing assimilation and fractional crystallization (AFC) processes to take place. The chemical and isotopic composition of Camiguin lavas bears strong resemblance to the majority of lavas from the central Mindanao volcanic field confirming that Camiguin is an extension of the tectonically complex Central Mindanao Arc (CMA). The most likely source of Camiguin and most CMA magmas is the mantle wedge metasomatized by fluids dehydrated from a subducted slab. Some Camiguin high-silica lavas are similar to high-silica lavas from Mindanao, which have been identified as “adakites” derived from direct melting of a subducted basaltic crust. More detailed comparison of Camiguin and Mindanao adakites with silicic slab-derived melts and magnesian andesites from the western Aleutians, southernmost Chile and Batan Island in northern Philippines indicates that the Mindanao adakites are not pure slab melts. Rather, the CMA adakites are similar to Camiguin high-silica lavas which are products of an AFC process and have negligible connection to melting of subducted basaltic crust.

Mantle metasomatic enrichment versus arc crust contamination in the Philippines: Oxygen isotope study of Batan ultramafic nodules and northern Luzon arc lavas

Fifty new oxygen isotopic analyses have been obtained on metasomatized peridotite nodules from Batan Island (Philippines) as well as on their host lavas and other upper Tertiary and Quaternary volcanic rocks from the northern part of the Luzon arc. They are used to investigate the possible mechanisms of the crustal component contribution which were previously considered in this arc on the basis of trace-element and SrNdPbTh isotopic variations observed on the same samples. Namely, they allow to distinguish mantle metasomatism by fluids carrying a sedimentary component from wall-rock contamination during magma ascent or storage. Ultramafic nodules display MORB-type δ 18O-values (+ 5.4 to + 6.1‰). Their OSr and ONd isotopic patterns are consistent with enrichment of a highly depleted-type mantle source by <3% bulk sediments. Their host lavas display grossly similar isotopic features, although some slightly higher δ 18O-values (up to + 6.8‰) may have resulted from minor crustal contamination or fluid exchange. For other lavas in the northern Luzon arc, combined Sr, Nd and O data indicate that both source and crustal contamination are involved to various degrees along the different sections of the arc, varying with local geodynamic conditions. As a whole, the chemical budget of the northern Luzon arc is dominated by source metasomatic enrichment processes, but the effects of crustal contamination are detectable both in its northern part (collision regime) and southern part (subduction of relatively young oceanic crust, presumably devoid of an important sedimentary cover). The precise nature of the sedimentary components involved in mantle enrichment processes is difficult to identify. It is suggested that the imprint of pelagic sediments might have been stored in the mantle source as a result of previous Tertiary subduction stages, before the recent addition of bulk terrigenous sediment. Such a two-stage process may explain the peculiar NdSrO signatures of northern Luzon ultramafic nodules and host lavas.

Four New Species of Lycodon (Serpentes: Colubridae) from the Northern Philippines

Four new species of the genus Lycodon (L. alcalai, L. bibonius, L. chrysoprateros, and L. solivagus) are described from Batan, Camiguin, Dalupiri, and Luzon islands of the northern Philippines. These species are similar to L. dumerili and L. muelleri but distinct from other Philippine congeners by having a slightly arched maxilla, medially divided nasal, and an entire anal shield. Lycodon alcalai and L. chrysoprateros differ from all other Philippine species of Lycodon in lacking transverse light bands on all of the body and tail. Lycodon alcalai differs from L. chrysoprateros in having more than 200 ventral scales (less than 195 in L. chrysoprateros). Lycodon bibonius is distinct from other Lycodon species in the Philippines in having 22-25 and 16-21 pale bands on the body and tail, respectively; L. solivagus is characterized by 13-14 pale bands occurring only on the anterior three-fourths of the body.

Two New Species of the Triplefin Fish Genus Helcogramma (Tripterygiidae) from the Western Pacific Ocean

Two new species of Helcogramma are described and compared with other members of the H.fuscopinna species complex, a monophyletic group comprising two distinct sub-groups: a pale-bodied sub-group that includes H. aquila (n. sp., Batan Islands), H. sp. 1 (Papua New Guinea), H. sp. 2 (Rotuma Island, Fiji), and H. sp. 3 (Vatoa Island, Fiji); and a dark-bodied sub-group that includes H. habena (n. sp., Batan Islands to Taiwan), H. fuscopinna (western Indian Ocean), H. sp. 4 (Philippines), and H. sp. 5 (Flores Island, Indonesia). Zoogeographic implications of the geographic distribution patterns are briefly discussed.

Mantle metasomatism above subduction zones: Trace-element and radiogenic isotope characteristics of peridotite xenoliths from Batan Island (Philippines)

Trace-element abundances and radiogenic isotope ratios have been determined for a suite of upper mantle-derived xenoliths collected from Pliocene-Quaternary andesitic lavas on Batan Island, northernmost Philippines. The xenoliths exhibit mineralogical changes and large ion lithophile enrichment indicative of metasomatism involving H2O-rich fluids. Strontium and neodymium isotopes in the xenoliths are not totally consistent with those in host lavas, but a common signature is indicated by the fact that all samples plot below the mantle array. The flux of fluids in the mantle wedge probably occurred over a long period of time. The flux induced large but variable changes in mineral and trace and isotopic compositions, and ultimately resulted in the melting of the peridotites and production of island-arc lavas.

A New Species of Enoplometopus (Thalassinidea: Axiidae) from the Northern Philippines

ABSTRACT Enoplometopuschacei is described from a single male taken from shallow water at Batan Island in the Philippines. The species, a member of the subgenus Enoplometopus, is characterized primarily by the possession of an overall orange-red integumental pigment with few color spots on the ventrolateral carapace, as well as by several more subtle features of the appendages.

A NEW SPECIES OF ENOPLOMETOPUS (THALASSINIDEA: AXIIDAE) FROM THE NORTHERN PHILIPPINES

ABSTRACT Enoplometopuschacei is described from a single male taken from shallow water at Batan Island in the Philippines. The species, a member of the subgenus Enoplometopus, is characterized primarily by the possession of an overall orange-red integumental pigment with few color spots on the ventrolateral carapace, as well as by several more subtle features of the appendages.

Principal Events that Happened in the Batanes Islands from 1898 to 1899

Principal Events that Happened in the Batanes Islands from 1898 to 1899

穀類における貯蔵でんぷんのうるち―もち性とその地理的分布

Cereals with waxy (i. e, glutinous) endosperm, such as rice, foxtail millet and common millet, are staples commonly found not only in Japan but also in various countries of East Asia. In the present article the geographical distributions of the waxy endosperm of seven species of cereals and their ethnobotanical significance are discussed. Based on recent findings and analyses of waxy and non-waxy perisperms in Anraranthus hypochondriacus collected in Nepal, the origin and dispersal of waxy perisperm of this species are also reported. Waxy endosperm is found in Oryza sativa (rice), Zea nays (maize), Hordeum vulgare (barley), Coix lacryma-jobi var, nta-yuen (Job's tears), Setaria italica (foxtail millet), Panicum uniliaceum (common millet) and Sorghum bicolor (sorghum). Cryza sativa: The waxy endosperm of Oryza sativa was first reported by Gris in 1860. After examining many indigenous varieties to nine geographical regions ranging from India to Japan, Iizuka et al. (1977) concluded that (1) in India, Sri Lanka and Nepal there were almost no waxy forms, (2) waxy varieties were abundant in samples from Indochina, Thailand and Burma, whereas (3) rather high frequencies were observed for non-waxy varieties from Japan and northern China. Watabe (1967) indicated that glutinous rice cultivation in Southeast Asia appears to center in northern and northeastern Thailand and Laos spreading to the surrounding regions of Burma, Yunnan, Vietnam and Cambodia. Zea mays: Waxy maize was found by Collins (1909) in a collection of specimens from China. This type of maize has generally been reported from northern Burma, Assam, China, Korea and Japan. Maize was domesticated first in the New World, but the waxy variety clearly originated from East Asia having developed after the introduction of maize from the New World. Hordeum vulagre: The waxy form of barley is found only in China, Korea and Japan. In Japan it was found sporadically in areas facing the Seto Inland Sea and in northern Kyushu. According to Nakao (1950), this form can be classified into three varieties which have in common naked and purple-colored grains. Coix lacryna jobi var. ma-yuen: Kempton (1921) observed both waxy and non-waxy forms of Job's tears in samples from Burma, India, the Philippines and China. However, in East Asia, only the waxy form is commonly grown. Setaria italica: Of the 406 samples collected by the author at various locations ranging from Europe to East Asia, 221 had waxy endosperm (54.4%) and 185 had non-waxy endosperm (45.6%). The former was found in Japan, Korea, China, Formosa, Luzon Island (the Philip-pines) and Thailand, but only the non-waxy form was isolated in samples from the Batan Islands (the Philippines), Halmahera Island (Indonesia), Nepal, India, Afghanistan, Central Asia and Europe. The obvious gaps in the geographical distribution of the waxy form of foxtail millet have been recognized in two places. One is the Bashi Channel between Formosa (includ-ing the Lan Yi Islands) and the Batan Islands. The other seems to be between Nepal-India and Assam. It is assumed that the gap at the Bashi Channel is related to the importance of the waxy variety in the ritual life of the native tribes inhabiting the Formosan mountains and the Lan Yu Islands. No reasonable explanation, however, of the other can be given at present. Panicum miliaceum: In spite of the wide occurrence of this species in Eurasia, studies of the geographical distribution of its waxy varieties have not been made. To the extent that could be examined by this study, the waxy form was detected only in specimens from Japan, Korea and China. The small number of samples from Afghanistan, Central Asia and Europe included only the non-waxy form. Sorghum bicolor: The waxy form of this species has been reported from Java, India, the Philippines, China and Japan. According to the present survey, the waxy form is very common in Korea and Japan. However,

On Eliciting Process of Covert Categories : A Commentary Note on Folk Bio-taxonomy of Batan Island, Philippines

On Eliciting Process of Covert Categories : A Commentary Note on Folk Bio-taxonomy of Batan Island, Philippines

Butterflies from Batan Island, the northern frontier of the Philippines

Butterflies from Batan Island, the northern frontier of the Philippines

Some Aspects of the Society on Batan Island, Philippines

Some Aspects of the Society on Batan Island, Philippines

Some Cultivated Plants of the Formosan Aborigines, and their Relation of the Ethnic History of Formosa

Plant geography often occupies an important position in the study of ethnology, and it is not rare that studies of cultivated plants furnish the answers to certain questions of racial migration, cultural contact, etc. In such cases, it is obvious that care must be taken to ascertain whether such plant grows wild or whether it was introduced. In the present state of our scanty knowledge concerning the ethnic history of the Formosan aborigines, it may be useful to consider the original homes and migration routes of some of the Formosan cultivated plants that seem to have some relation to the ethnic history of Formosa. The present paper concerns the following plants:(1) Artocarpus communis, (2) Pometia pinnata, (3) Semecarpus vernicifera, (4) Musa texitilis, (5) Acacia confusa, and (6) Dioscorea fasciculata. of these six kinds of cultivated plants, (1) to (4) are found cultivated by the Ami and Kuvalan tribes, inhabiting the plain on the eastern coast of Formosa. Plants, (5) and (6) are restricted to a narrow area occupied by the Paiwan tribe, S. Formosa.It is believed that the ethnic groups of southern and eastern Formosa comprise a mixture of a number of tribes from various places, so that it is very difficult to pick out each single element. Upon examining the original localities of these cultivated plants, the writer is led to conclude that, at least, the following three routes of cultural migration from the south existed in the southern and eastern parts of Formosa.1. That from the Batanes Islands to Botel Tobago (Kotosho), in which the Yami tribe is concerned.2. That from somewhere in the Philippines to more than one centre on the eastern coast of Formosa, in which some groups of the Ami and Kuvalan tribes are concerned.3. That from the northeastern coast of Luzon to the southern extremity of Formosa, in which a member of the Paiwan tribe is concerned.

Some Problems Concerning the Biogeography of Kôtôsyo [3

Botel Tobago, or Kotosho, which is a small island situated about 40 nautical miles southeast of Formosa, presents certain interesting characteristics from the standpoint of animal and, plant distribution. The author, who has visited the island five times since 1927, investigated the local fauna and flora, spending about 200 days in collecting material. The present paper deals with certain problems concerning the biogeography of the island, examines the nature of the fauna, flora, and vegetation, and discusses in some detail the origin and migration of life there. The main points treated therein may be summarized as follows: 1. Geologically speaking, from the fact that Kotosho, together with Kashoto, shows marked affinity with the Batanes and Babuyanes islands of the Philippines rather than with the mainland of Formosa itself, these islands are regarded as a northern extension of the Philippines. 2. Climatologically, both Kotosho and Kashoto are properly included in the same climatographical province as the Batanes and Babuyanes islands of the Philippines. 3. Judged from its fauna, Kotosho undoubtedly belongs to the Orientalregion, consisting of a mixture of forms belonging to the Indochinese, Indomalayan, and the Philippine subregions, of which the last element is clearly predominant. 4. Faunally, Kotosho clearly resembles the Batanes islands more than any other neighbouring region. 5. The flora of Kotosho, with its pronounced Philippine characters, is in striking contrast to that of the mainland of Formosa. 6. In vegetation types, Kotosho is totally defferent from those of the Formosan mainland, showing remarkable relations to the Philippines. 7. When dividing the regions adjacent to Formosa into biogeographical provinces, Kotosho, together with Kashoto, should be included in the Batanes-Babuyanes province. 8. The northern part of the Neo-Wallace line as modified by Merrill and Dickerson should be revised and made to pass between the two islands (Kotosho and Kashoto) and the mainland of Formosa. 9. The extreme end of the Neo-Wallace line ought to be drawn between the Bonin and the Micronesian islands, should Dr. Kuroda's opinion that the line, instead of stopping in the neighbourhood of Formosa, ought to be extended still farther, be accepted. 10. If the Neo-Wallace line runs between the Bonin Islands and Micronesia, Weber's line is then properly drawn between Micronesia and New Guinea. 11. The most potent agency acting on the present distribution of life in Kotosho is without doubt ecological, among which the climatological conditions should mostly be taken into account. 12. Besides the present ecological environments of Kotosho, the existence of a land bridge fomerly connecting Formosa via Kotosho and the Batanes islands with Luzon is also an important key to the solution of present life distribution, through which passage, Kotosho received intermigration of life from both north and south. 13. This hypothetical land bridge broke off between Kotosho and Formosa after the southward migration of Formosan forms had ended, the water becoming a barrier to the northward migration of Philippine forms to the mainland of Formosa. 14. The land bridge here postulated is supposed to have existed in late Pliocene or early Pleistocene, migration of life by this route having been accelerated by climatic changes during the Ice-age. 15. The temperate-zone types of animals and plants in the high altitudes of N. Luzon came from the north, not by the Oligoceneearly Miocene land connection as erroneously suggested by Merrill and Dickerson, but by the land-bridge of geologically recent times as just mentioned.

III.—The Coal Deposits of Batan Island, with Notes on the General and Economic Geology of the adjacent region. By Warben D. Smith, B.S., M.A., Geologist, Mining Bureau. Bulletin No. 5, Department of the Interior: The Mining Bureau, Manila. 8vo; pp. 56, and 21 plates (maps, sections, photomicrographs of rocks and fossils). (Manila: Bureau of Printing, 1905.)

III.—The Coal Deposits of Batan Island, with Notes on the General and Economic Geology of the adjacent region. By Warben D. Smith, B.S., M.A., Geologist, Mining Bureau. Bulletin No. 5, Department of the Interior: The Mining Bureau, Manila. 8vo; pp. 56, and 21 plates (maps, sections, photomicrographs of rocks and fossils). (Manila: Bureau of Printing, 1905.)