Abhay Mudholkar | National Institute of Oceanography (original) (raw)

Papers by Abhay Mudholkar

Chemical Geology, 2012

Mineralogy and geochemistry of the ferromanganese oxides collected from two seamounts in the Anda... more Mineralogy and geochemistry of the ferromanganese oxides collected from two seamounts in the Andaman Sea have been investigated with special reference to the solid phase partitioning behavior of rare earth elements (REEs). Bulk elemental compositions indicate that the oxides from a volcanic cratered seamount, CSM, are hydrothermal while those from another seamount, SM2, are hydrogenous in origin. The distributions of REEs and yttrium in four geochemical phases (viz. easily exchangeable, Mn-oxide, Fe-oxyhydroxide and residual) of CSM-oxides were distinctly different from that of SM2oxides. In CSM-oxides, the REEs and yttrium are mainly associated with Fe-oxyhydroxide phase while in SM2-oxides, both Mn-oxide and Fe-oxyhydroxide phases contain the major fraction of these elements. The exchangeable and residual phases of both hydrothermal and hydrogenous oxides have extremely low REE-content. The shale normalized negative Ce-anomalies and relative enrichment of heavy REE, characteristic of hydrothermal oxides, are retained in Fe-oxyhydroxide phase. In hydrogenous oxides, the positive Ce-anomalies occurred in both Fe and Mn-oxide phases while negative Y-anomalies were found only in Fe-oxyhydroxide phase. The phase distribution of REEs and yttrium in hydrothermal oxides is described in terms of co-precipitation and adsorption of their halide complexes and available free ions in hydrothermal solutions. Instead, adsorption of major carbonate species from seawater primarily regulates the partitioning of REEs among the co-existing phases of hydrogenous oxides.

10th International Congress of the Brazilian Geophysical Society & EXPOGEF 2007, Rio de Janeiro, Brazil, 19-23 November 2007, 2007

The PLURIEL cruise (Marion Dufresne II, 19 September 31 October 2006) had as main objective the s... more The PLURIEL cruise (Marion Dufresne II, 19 September 31 October 2006) had as main objective the study of the temporal evolution of the interaction between the St Paul-Amsterdam hotspot (SPA) and the Southeast Indian Ridge (SEIR) over the last 15 m.y.. The SPA-SEIR system is an ideal target to study the transition of hotspot activity from an intraplate to an axial context. North-east of the SPA plateau, which corresponds to the axial activity of the hotspot, a chain of volcanoes possibly marks its intraplate activity. The most recent volcanic activity is located east of the Amsterdam island, very close to the ridge axis. The first results of the cruise show that the time evolution of this ridge-hotspot interaction is very complex.

Sedimentary Geology, 1988

... J. Earth Sci. 11 (1974), pp. 1594–1605. NVBS Dutt, The Bhima Group of ... 1–12. SV Joshi and ... more ... J. Earth Sci. 11 (1974), pp. 1594–1605. NVBS Dutt, The Bhima Group of ... 1–12. SV Joshi and VV Peshwa, Occurrence, morphology and probable mode of formation of glauconite from Ladlapur, Shahabad District, Karnataka State, Glauconite: Form and Function, Curr. ...

Current Science, 2012

Abstract: Finding of stone anchors in the onshore and offshore regions of India points to maritim... more Abstract: Finding of stone anchors in the onshore and offshore regions of India points to maritime contacts with neighbouring countries. This communication reports a new Indo-Arabian type stone anchor recovered from a depth of 53 m off the coast of Gulf of Kachchh, Gujarat, India. The anchor stone is composed of sharp angular quartz and feldspar grains floating in a ferruginous matrix with point contacts between them as seen under a microscope. SEM–EDS studies showed few and isolated zircon and apatite grains as ...

Quaternary International, 2013

Pumice clasts, partially and fully coated with ferro-manganese oxide from the Central Indian Ocea... more Pumice clasts, partially and fully coated with ferro-manganese oxide from the Central Indian Ocean Basin (CIOB) were analysed for major, trace and rare earth elements; and glass and mineral grain chemistry to assess their possible source. These pumice clasts have ~ 95 % glassy matrix with ~ 5% of plagioclase, ortho-pyroxene, amphibole and spinel mineral grains. Pumice is rhyolitic, with high content of silica and total alkalis and show strong light rare earth element enrichment, with La ~ 100 times enriched compared to chondritic abundance and exhibits a pronounced negative Eu-anomaly. Both the partially and fully coated pumice clasts have a similar composition, but this, and their, glass and mineral (orthopyroxene) chemistry differs from all tuffs known to have erupted from the Toba Caldera Complex. The partial to complete Fe-Mn oxide coating suggests pumice probably predate activity from the Toba caldera. Their general composition is consistent with a volcanic arc origin, and show similarities to rhyolitic eruptives from Sumatra. The distribution of partially and fully coated pumice in the CIOB overlaps with that of uncoated pumice from the voluminous YTT eruption, suggesting that other large rhyolitic calderas active in Sumatra/Indonesia. Similarities in composition to ash layers from the CIOB suggest a possible Late Miocene-Late Pleistocene age for these pumices.

Surveys to explore the slow to medium spreading Carlsberg Ridge, which acts as a plate boundary b... more Surveys to explore the slow to medium spreading Carlsberg Ridge, which acts as a plate boundary between the Indian and African plates in the northern Arabian Sea, have been ongoing since 1996. A ~ 100 km long section of the Carlsberg ridge was surveyed with multi-beam bathymetry, gravity and magnetics and seabed sampling during the cruise on board OR/V Sagar Kanya (SK-114) in June-July 1996. In July-August 2000, a cruise (SK-154) was undertaken to augment the earlier data, and an area of ~ 17,000 km2 was covered with the multi-beam

Episodes

This study reports new petrological and geochemical data of submarine volcanic rocks dredged from... more This study reports new petrological and geochemical data of submarine volcanic rocks dredged from the Andaman arc, northeastern Indian Ocean and evaluates their petrogenetic and tectonic implications. The studied samples exhibit wide range of compositions including basalts, andesites, dacites and rhyolites depicting BADR trend of magmatic differentiation. The basalts are porphyritic and composed of calcic plagioclase phenocrysts embedded in the groundmass consisting of plagioclase, clinopyroxene and volcanic glass. Andesite and dacites comprise clusters of plagioclase are phenocrysts embedded in glassy ground mass depicting glomeroporphyritic and vitrophyric textures. Plagioclase microlites in andesites show primary flow texture. Rhyolites from the study area porphyritic in nature predominantly consisting K-feldspar, quartz and plagioclase phenocrysts embedded in a silica rich merocrystalline groundmass of quartz, K-feldspar, biotite, opaque and glass. Plagioclase compositions in basalts and rhyolites correspond to An76-78 and An5-8 respectively. Geochemical and tectonic attributes marked by uniform LILE-LREE enriched, HFSE depleted trends corroborate (i) Mariana-type subduction of old, cold, thick and dense Indian Ocean lithosphere (ii) slabdehydration, variable slab-mantle interaction, metasomatism and flux melting of mantle wedge and (iii) magma underplating and melting of lower oceanic crust resulting into calc-alkaline magmatism of B-AD -R compositional spectra.

Geo Marine Letters, Aug 1, 1999

Petrography, petrochemistry, and mineral chemistry of basalts from the Woodlark, Manus, and Lau b... more Petrography, petrochemistry, and mineral chemistry of basalts from the Woodlark, Manus, and Lau basins from the southwest Paci"c, have been studied to understand their magmatic evolution. Basalt from the western Woodlark Basin (Dobu Seamount) indicates mixing of a near-primitive magma with fractionated basaltic melt in shallow magma chambers. Basalts from Manus Basin and Central Lau Spreading Center (Lau Basin) are typical N-MORBs, and they exhibit olivine fractionation under high oxidizing conditions while basalts from Mangatolu Triple Junction (Lau Basin) are enriched in Al O , K O, and Zr indicative of a contribution from a subducting plate. #ank. This ridge extends for about 3 km and has an

Marine Geology, Jul 1, 2008

Marine Geology, Jun 1, 1995

The occurrence of pumice in the Central Indian Basin (CIB) has been a controversy. Some are of th... more The occurrence of pumice in the Central Indian Basin (CIB) has been a controversy. Some are of the opinion that these pumices are erupted from a volcano along the Ninetyeast ridge while others suggest the Indonesian arc volcanism as their probable source. Recently, it is also suggested that the pumice are the products of in-situ silicic volcanism in the CIB. This study was initiated in order to resolve this controversy about the origin of the fresh pumice from the CIB. The fresh pumice pieces of different sizes and shapes were collected from the surficial sediments of the CIB from an average depth of about 5000 m (12"S, 76"E). Glass is the main phase comprising about 95% (volume) and resembles the matrix glass in Krakatau 1883 dacitic pumice which is also very poor (< 5%) in the modal mineral composition. The mineral and glass analyses were carried out with the help of the electron microprobe. The orthopyroxenes, clinopyroxenes, plagioclases and spinels are the mineral phases present in these pumices. The pyroxenes have similar wo, en and fs components to those previously reported from the 1883 Krakatau eruption products. Geochemically, these fresh pumices have a high SiO, content (71%) and high total alkali content (8%) similar to 1883 eruption products of Krakatau. Thus based on the similarities in mineralogy and glass chemical composition it is inferred that these fresh pumices are the products of the fierce 1883 eruption of the Krakatau volcano in the Sunda Strait of the Indonesian arc.

AbStRAct Sparse and non-availability of high resolution geophysical data hindered the delineation... more AbStRAct Sparse and non-availability of high resolution geophysical data hindered the delineation of accurate morphology, structural configuration, tectonism and spreading history of Carlsberg Ridge (CR) and Central Indian Ridges (CIR) in the Indian Ocean between Owen fracture zone at about 10 o N, and the Rodriguez Triple Junction at ~25 o S. Analysis of available multibeam bathymetry, magnetic, gravity, seabed sampling on the ridge crest, and selected water column data suggest that even with similar slow spreading history the segmentation significantly differ over the CR and CIR ridge systems. Topography, magnetic and gravity signatures indicate non-transform discontinuity over CR and suggest that it has relatively slower spreading history than CIR. Magmatic and less magmatic events characterize CR and CIR respectively and well defined oceanic core complex (OCC) are confined only to segments of the CIR. The mantle Bouguer anomaly signatures over the ridges suggest crustal accretio...

Surveys to explore the slow to medium spreading Carlsberg Ridge, which acts as a plate boundary b... more Surveys to explore the slow to medium spreading Carlsberg Ridge, which acts as a plate boundary between the Indian and African plates in the northern Arabian Sea, have been ongoing since 1996. A ~ 100 km long section of the Carlsberg ridge was surveyed with multi-beam bathymetry, gravity and magnetics and seabed sampling during the cruise on board

ABSTRACT Fourteen glassy selvages from ocean floor pillow basalts were analysed in situ by a comb... more ABSTRACT Fourteen glassy selvages from ocean floor pillow basalts were analysed in situ by a combination of Electron Probe Micro Analysis (EPMA) and Laser Ablation- Inductively Coupled Plasma Mass Spectrometry (LAM-ICPMS) for major and trace element geochemistry respectively. These samples were collected from the 4°06&#39; 3°50&#39;N segment of the Carlsberg Ridge (CR), Indian Ocean during the SK194 cruise. The glasses are dark to light brown in colour and show patches of devitrification to microcrystalline plagioclase, olivine, clinopyroxene and rare spinel + pyrite grains with drip-like protrusions and micro vesicles. However, here we present a discussion exclusively on analyses carried out on carefully selected pure glassy domains. The glasses were mounted on 25 mm epoxy blocks and were sectioned and polished using new polishing pads to avoid contamination. This ensured exposure of the central portions of the glasses and selection of fresh areas for analysis. The CR glass compositions when compared with similar samples of Mid Oceanic Ridge Basalts (MORB) from elsewhere, show peculiar major and trace element patterns. Major element chemistry of the glasses are characterized by an average of 50.49 (wt.%) SiO , low CaO/Al O (0.73) and a range of Mg# (Mg/Mg+Fe) 2 2 3 from 41-53 similar to other N-MORB compositions. In contrast, the trace element compositions show a combination of both N-MORB and E-MORB signatures. LILE elements mimic typical N-MORB compositions whereas other trace elements show E-MORB signatures. N-MORB-normalised trace element concentrations show variable U, Pb and Nb anomalies suggesting a source that is depleted in highly incompatible elements similar to that of the glasses from Axial and Woodlark spreading centers. 54 2005, NIO, GOA Inter Ridge Workshop on Tectonic &amp; Oceanic Processes Along the Indian Ocean Ridge System 19-21 January, 2005 S2-MT-09P

Chemical Geology, 2012

Mineralogy and geochemistry of the ferromanganese oxides collected from two seamounts in the Anda... more Mineralogy and geochemistry of the ferromanganese oxides collected from two seamounts in the Andaman Sea have been investigated with special reference to the solid phase partitioning behavior of rare earth elements (REEs). Bulk elemental compositions indicate that the oxides from a volcanic cratered seamount, CSM, are hydrothermal while those from another seamount, SM2, are hydrogenous in origin. The distributions of REEs and yttrium in four geochemical phases (viz. easily exchangeable, Mn-oxide, Fe-oxyhydroxide and residual) of CSM-oxides were distinctly different from that of SM2oxides. In CSM-oxides, the REEs and yttrium are mainly associated with Fe-oxyhydroxide phase while in SM2-oxides, both Mn-oxide and Fe-oxyhydroxide phases contain the major fraction of these elements. The exchangeable and residual phases of both hydrothermal and hydrogenous oxides have extremely low REE-content. The shale normalized negative Ce-anomalies and relative enrichment of heavy REE, characteristic of hydrothermal oxides, are retained in Fe-oxyhydroxide phase. In hydrogenous oxides, the positive Ce-anomalies occurred in both Fe and Mn-oxide phases while negative Y-anomalies were found only in Fe-oxyhydroxide phase. The phase distribution of REEs and yttrium in hydrothermal oxides is described in terms of co-precipitation and adsorption of their halide complexes and available free ions in hydrothermal solutions. Instead, adsorption of major carbonate species from seawater primarily regulates the partitioning of REEs among the co-existing phases of hydrogenous oxides.

10th International Congress of the Brazilian Geophysical Society & EXPOGEF 2007, Rio de Janeiro, Brazil, 19-23 November 2007, 2007

The PLURIEL cruise (Marion Dufresne II, 19 September 31 October 2006) had as main objective the s... more The PLURIEL cruise (Marion Dufresne II, 19 September 31 October 2006) had as main objective the study of the temporal evolution of the interaction between the St Paul-Amsterdam hotspot (SPA) and the Southeast Indian Ridge (SEIR) over the last 15 m.y.. The SPA-SEIR system is an ideal target to study the transition of hotspot activity from an intraplate to an axial context. North-east of the SPA plateau, which corresponds to the axial activity of the hotspot, a chain of volcanoes possibly marks its intraplate activity. The most recent volcanic activity is located east of the Amsterdam island, very close to the ridge axis. The first results of the cruise show that the time evolution of this ridge-hotspot interaction is very complex.

Sedimentary Geology, 1988

... J. Earth Sci. 11 (1974), pp. 1594–1605. NVBS Dutt, The Bhima Group of ... 1–12. SV Joshi and ... more ... J. Earth Sci. 11 (1974), pp. 1594–1605. NVBS Dutt, The Bhima Group of ... 1–12. SV Joshi and VV Peshwa, Occurrence, morphology and probable mode of formation of glauconite from Ladlapur, Shahabad District, Karnataka State, Glauconite: Form and Function, Curr. ...

Current Science, 2012

Abstract: Finding of stone anchors in the onshore and offshore regions of India points to maritim... more Abstract: Finding of stone anchors in the onshore and offshore regions of India points to maritime contacts with neighbouring countries. This communication reports a new Indo-Arabian type stone anchor recovered from a depth of 53 m off the coast of Gulf of Kachchh, Gujarat, India. The anchor stone is composed of sharp angular quartz and feldspar grains floating in a ferruginous matrix with point contacts between them as seen under a microscope. SEM–EDS studies showed few and isolated zircon and apatite grains as ...

Quaternary International, 2013

Pumice clasts, partially and fully coated with ferro-manganese oxide from the Central Indian Ocea... more Pumice clasts, partially and fully coated with ferro-manganese oxide from the Central Indian Ocean Basin (CIOB) were analysed for major, trace and rare earth elements; and glass and mineral grain chemistry to assess their possible source. These pumice clasts have ~ 95 % glassy matrix with ~ 5% of plagioclase, ortho-pyroxene, amphibole and spinel mineral grains. Pumice is rhyolitic, with high content of silica and total alkalis and show strong light rare earth element enrichment, with La ~ 100 times enriched compared to chondritic abundance and exhibits a pronounced negative Eu-anomaly. Both the partially and fully coated pumice clasts have a similar composition, but this, and their, glass and mineral (orthopyroxene) chemistry differs from all tuffs known to have erupted from the Toba Caldera Complex. The partial to complete Fe-Mn oxide coating suggests pumice probably predate activity from the Toba caldera. Their general composition is consistent with a volcanic arc origin, and show similarities to rhyolitic eruptives from Sumatra. The distribution of partially and fully coated pumice in the CIOB overlaps with that of uncoated pumice from the voluminous YTT eruption, suggesting that other large rhyolitic calderas active in Sumatra/Indonesia. Similarities in composition to ash layers from the CIOB suggest a possible Late Miocene-Late Pleistocene age for these pumices.

Surveys to explore the slow to medium spreading Carlsberg Ridge, which acts as a plate boundary b... more Surveys to explore the slow to medium spreading Carlsberg Ridge, which acts as a plate boundary between the Indian and African plates in the northern Arabian Sea, have been ongoing since 1996. A ~ 100 km long section of the Carlsberg ridge was surveyed with multi-beam bathymetry, gravity and magnetics and seabed sampling during the cruise on board OR/V Sagar Kanya (SK-114) in June-July 1996. In July-August 2000, a cruise (SK-154) was undertaken to augment the earlier data, and an area of ~ 17,000 km2 was covered with the multi-beam

Episodes

This study reports new petrological and geochemical data of submarine volcanic rocks dredged from... more This study reports new petrological and geochemical data of submarine volcanic rocks dredged from the Andaman arc, northeastern Indian Ocean and evaluates their petrogenetic and tectonic implications. The studied samples exhibit wide range of compositions including basalts, andesites, dacites and rhyolites depicting BADR trend of magmatic differentiation. The basalts are porphyritic and composed of calcic plagioclase phenocrysts embedded in the groundmass consisting of plagioclase, clinopyroxene and volcanic glass. Andesite and dacites comprise clusters of plagioclase are phenocrysts embedded in glassy ground mass depicting glomeroporphyritic and vitrophyric textures. Plagioclase microlites in andesites show primary flow texture. Rhyolites from the study area porphyritic in nature predominantly consisting K-feldspar, quartz and plagioclase phenocrysts embedded in a silica rich merocrystalline groundmass of quartz, K-feldspar, biotite, opaque and glass. Plagioclase compositions in basalts and rhyolites correspond to An76-78 and An5-8 respectively. Geochemical and tectonic attributes marked by uniform LILE-LREE enriched, HFSE depleted trends corroborate (i) Mariana-type subduction of old, cold, thick and dense Indian Ocean lithosphere (ii) slabdehydration, variable slab-mantle interaction, metasomatism and flux melting of mantle wedge and (iii) magma underplating and melting of lower oceanic crust resulting into calc-alkaline magmatism of B-AD -R compositional spectra.

Geo Marine Letters, Aug 1, 1999

Petrography, petrochemistry, and mineral chemistry of basalts from the Woodlark, Manus, and Lau b... more Petrography, petrochemistry, and mineral chemistry of basalts from the Woodlark, Manus, and Lau basins from the southwest Paci"c, have been studied to understand their magmatic evolution. Basalt from the western Woodlark Basin (Dobu Seamount) indicates mixing of a near-primitive magma with fractionated basaltic melt in shallow magma chambers. Basalts from Manus Basin and Central Lau Spreading Center (Lau Basin) are typical N-MORBs, and they exhibit olivine fractionation under high oxidizing conditions while basalts from Mangatolu Triple Junction (Lau Basin) are enriched in Al O , K O, and Zr indicative of a contribution from a subducting plate. #ank. This ridge extends for about 3 km and has an

Marine Geology, Jul 1, 2008

Marine Geology, Jun 1, 1995

The occurrence of pumice in the Central Indian Basin (CIB) has been a controversy. Some are of th... more The occurrence of pumice in the Central Indian Basin (CIB) has been a controversy. Some are of the opinion that these pumices are erupted from a volcano along the Ninetyeast ridge while others suggest the Indonesian arc volcanism as their probable source. Recently, it is also suggested that the pumice are the products of in-situ silicic volcanism in the CIB. This study was initiated in order to resolve this controversy about the origin of the fresh pumice from the CIB. The fresh pumice pieces of different sizes and shapes were collected from the surficial sediments of the CIB from an average depth of about 5000 m (12"S, 76"E). Glass is the main phase comprising about 95% (volume) and resembles the matrix glass in Krakatau 1883 dacitic pumice which is also very poor (< 5%) in the modal mineral composition. The mineral and glass analyses were carried out with the help of the electron microprobe. The orthopyroxenes, clinopyroxenes, plagioclases and spinels are the mineral phases present in these pumices. The pyroxenes have similar wo, en and fs components to those previously reported from the 1883 Krakatau eruption products. Geochemically, these fresh pumices have a high SiO, content (71%) and high total alkali content (8%) similar to 1883 eruption products of Krakatau. Thus based on the similarities in mineralogy and glass chemical composition it is inferred that these fresh pumices are the products of the fierce 1883 eruption of the Krakatau volcano in the Sunda Strait of the Indonesian arc.

AbStRAct Sparse and non-availability of high resolution geophysical data hindered the delineation... more AbStRAct Sparse and non-availability of high resolution geophysical data hindered the delineation of accurate morphology, structural configuration, tectonism and spreading history of Carlsberg Ridge (CR) and Central Indian Ridges (CIR) in the Indian Ocean between Owen fracture zone at about 10 o N, and the Rodriguez Triple Junction at ~25 o S. Analysis of available multibeam bathymetry, magnetic, gravity, seabed sampling on the ridge crest, and selected water column data suggest that even with similar slow spreading history the segmentation significantly differ over the CR and CIR ridge systems. Topography, magnetic and gravity signatures indicate non-transform discontinuity over CR and suggest that it has relatively slower spreading history than CIR. Magmatic and less magmatic events characterize CR and CIR respectively and well defined oceanic core complex (OCC) are confined only to segments of the CIR. The mantle Bouguer anomaly signatures over the ridges suggest crustal accretio...

Surveys to explore the slow to medium spreading Carlsberg Ridge, which acts as a plate boundary b... more Surveys to explore the slow to medium spreading Carlsberg Ridge, which acts as a plate boundary between the Indian and African plates in the northern Arabian Sea, have been ongoing since 1996. A ~ 100 km long section of the Carlsberg ridge was surveyed with multi-beam bathymetry, gravity and magnetics and seabed sampling during the cruise on board

ABSTRACT Fourteen glassy selvages from ocean floor pillow basalts were analysed in situ by a comb... more ABSTRACT Fourteen glassy selvages from ocean floor pillow basalts were analysed in situ by a combination of Electron Probe Micro Analysis (EPMA) and Laser Ablation- Inductively Coupled Plasma Mass Spectrometry (LAM-ICPMS) for major and trace element geochemistry respectively. These samples were collected from the 4°06&#39; 3°50&#39;N segment of the Carlsberg Ridge (CR), Indian Ocean during the SK194 cruise. The glasses are dark to light brown in colour and show patches of devitrification to microcrystalline plagioclase, olivine, clinopyroxene and rare spinel + pyrite grains with drip-like protrusions and micro vesicles. However, here we present a discussion exclusively on analyses carried out on carefully selected pure glassy domains. The glasses were mounted on 25 mm epoxy blocks and were sectioned and polished using new polishing pads to avoid contamination. This ensured exposure of the central portions of the glasses and selection of fresh areas for analysis. The CR glass compositions when compared with similar samples of Mid Oceanic Ridge Basalts (MORB) from elsewhere, show peculiar major and trace element patterns. Major element chemistry of the glasses are characterized by an average of 50.49 (wt.%) SiO , low CaO/Al O (0.73) and a range of Mg# (Mg/Mg+Fe) 2 2 3 from 41-53 similar to other N-MORB compositions. In contrast, the trace element compositions show a combination of both N-MORB and E-MORB signatures. LILE elements mimic typical N-MORB compositions whereas other trace elements show E-MORB signatures. N-MORB-normalised trace element concentrations show variable U, Pb and Nb anomalies suggesting a source that is depleted in highly incompatible elements similar to that of the glasses from Axial and Woodlark spreading centers. 54 2005, NIO, GOA Inter Ridge Workshop on Tectonic &amp; Oceanic Processes Along the Indian Ocean Ridge System 19-21 January, 2005 S2-MT-09P