1 10 2 https://theses.otagogeology.org.nz/files/original/0365a07b8afd3f780d4b60021c6f1e2f.pdf 2d352518c71f6d3a458a0867ebabeca0 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format POLYGON ((163.184684990983726 -77.004224674025849,163.332660983376911 -77.081152379097816,163.394226518531099 -77.112870112136449,163.402256698733765 -77.116994784092427,163.490879044486917 -77.162326972036595,163.59980123093996 -77.217573808142902,163.669309860408248 -77.252562070896957,163.735767946975415 -77.285821862858015,163.791314848680287 -77.31347744139606,163.935743462084076 -77.384779968177227,163.957015544151858 -77.395208506100673,163.996806338550499 -77.414665704807604,164.003085985126177 -77.41773042870058,164.048192239690195 -77.439696689411718,164.616271439963697 -77.709388945869776,164.664958486730171 -77.731918731860972,164.700671752835575 -77.748387806526921,164.700151275948144 -77.776300262808675,164.698992552648804 -77.837993399512357,164.695775949569594 -78.006079615959351,164.69277005797116 -78.159067598202824,164.690106032397154 -78.291475107198579,164.690106036297237 -78.291475174387074,164.689788549228609 -78.307060446426647,164.557982328973821 -78.368215768190026,164.55322246620895 -78.370411333527542,164.476436720779219 -78.405706718185257,164.459226862968251 -78.413585690543954,164.370725610088954 -78.453920997092183,164.343728304506641 -78.466164917794814,164.237731084494385 -78.51396672300352,164.226820859117112 -78.518862605037171,164.138736791028975 -78.558224730296871,164.059085671554016 -78.593567530867062,163.877291943318255 -78.673352994510182,163.840415464971329 -78.68938977455737,163.541157617841435 -78.817727764777345,163.098249149913499 -79.00195791217277,162.7998833172405 -79.122374233387504,162.58742894019025 -79.206372686142174,162.42164414809298 -79.270936730235562,159.66027579076362 -79.24490118471013,159.704301191911156 -79.126357204783488,159.810095172874924 -78.830649952258071,159.815275017275212 -78.815763006727124,159.941518882926516 -78.783260124630303,160.228524357893349 -78.708470446592003,160.455576076954685 -78.648406365778825,160.550735279900834 -78.622993460720011,161.42795976482833 -78.381844145189675,161.439738442065391 -78.331718593851335,161.48921834210617 -78.116404401405788,161.490209012932013 -78.112013360469049,161.497397507886575 -78.080055046342409,161.515140540943889 -78.000443418646455,161.52536465975632 -77.954090347333164,161.531059537761678 -77.928123124147461,161.321945332845615 -77.852287030835001,161.254014668217422 -77.829920108827011,161.187485882623236 -77.816551583703969,161.145690122503538 -77.808129970911509,161.137701176121539 -77.806518219132926,161.12603445560481 -77.804163316044523,161.099882392755319 -77.798879533679909,161.079362605873825 -77.794728811589664,160.857521895441522 -77.749579112128515,160.745786082554957 -77.726645606640204,160.719616552025002 -77.721255580417164,160.671714288238093 -77.711370808764244,160.680526643571739 -77.668981242093452,160.680861813615678 -77.667363302372848,160.683591891348499 -77.654168974590235,160.686524417612503 -77.639965150271848,160.686669235036589 -77.639262893878723,160.472097268278105 -77.565317678911995,160.361907665308365 -77.24508434456051,160.463265720341724 -76.951841082443337,161.110754371935684 -76.926448199750055,161.550425820804179 -77.001486652438913,161.697868653902077 -77.001725441471038,161.737731827573697 -77.001775587283902,161.854699325938498 -77.001887489977591,161.955243292230449 -77.001941673254194,161.997167812697967 -77.001952794306959,162.352799900627332 -77.001775569852995,162.430004611660365 -77.001672909089649,162.830551004176186 -77.000772673481094,162.926049329750157 -77.000467020922969,162.991125506021632 -77.000238655414861,163.010951387428719 -77.000165847198346,163.010986568013379 -77.000165716572695,163.032111822790341 -77.000086471925115,163.17566302551981 -76.999502540245956,163.184684990983726 -77.004224674025849)) Author last name Last name of the Author Cook Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Craw, Dave Abstract The Abstract for this thesis South Victoria Land basement consists of Neoproterozoic metasediments and metavolcanic rocks which make up the Skelton Group. The Skelton Group was intruded by mafic and felsic plutons and dykes of the Granite Harbour Intrusives during the Ross Orogeny. Ages of plutonic rocks indicate that the Ross orogeny lasted from at least 550Ma (latest Neoproterozoic) to 477Ma (Ordovician) The metasediments of the Skelton Group are now metamorphosed and deformed but originally included intraformational conglomerates, greywacke, siltstone, mudstone, limestone and impure limestone. Coeval with sedimentation was intrusion and extrusion of basaltic plugs, sills and pillow lavas with P- and TMORB chemistry, and trachyte and rhyolite extrusives. These igneous rocks have an origin involving crustal contamination and indicate that the Skelton Group formed in a continental rift environment younger than 680Ma and probably younger than 630Ma. There has been variable deformation and metamorphism of the Skelton Group between lower green schist and upper amphibolite facies. Lithostratigraphic mapping of south Victoria Land is not possible due to extensive disruption and reconstitution of the Skelton Group during the Ross Orogeny. The Lower Baronick Formation (conglomerate and bimodal volcanics) is the only formation that is recognised and is sufficiently undeformed that bedding can be recognised. For mapping purposes, south Victoria Land is sub-divided into fault bounded sub-blocks (c.l-20km in size) each of which has had a relatively coherent geological history during the Ross Orogeny. These sub-blocks are grouped into one of four main structural blocks. Some of these four main blocks contain rocks with a wide range of structures and metamorphic grade. The southernmost block is the Skelton Block which covers 1400km2 and consists of 9 recognisable sub-blocks. Some of the sub-blocks, including Lower Baronick Formation, are relatively undeformed whereas others are totally reconstituted. The Skelton Block contains the least deformed rocks which yield the most information on the origin of the Skelton Group. The Koettlitz Block (290km2) contains two greenschist facies sub-blocks which are relatively unstrained, but very little is known about this block due to limited exposure. The Walcott Block (730km2) is made up of 5 sub-blocks. The sub-blocks include greenschist facies rocks preserving clastic textures, mid to upper amphibolite facies schists and migmatites and there are some high strain gradients between less deformed and more deformed rocks. The Walcott Block underwent extensional tectonics during the Ross Orogeny. The northernmost Dry Valleys Block (4600km2) consists of thoroughly transposed and reconstituted upper amphibolite facies schists and no sub-blocks have been recognised. Dry Valleys Block underwent extensional, compressional and strike slip tectonics during the Ross Orogeny. The boundaries between structural blocks appear to be steeply dipping NW striking faults. Only one of these faults, the Frio Shear Zone, is exposed and forms the boundary between Walcott Block and Dry Valleys Block. Frio Shear Zone has had a complex structural history of reactivation throughout the Ross Orogeny and the latest movement along which uplift of the Dry Valleys Block occurred is sinistralnormal. Some block boundaries are cut by Granite Harbour Intrusives whereas other block boundaries cut Granite Harbour Intrusives. The geological histories of the four main blocks indicate that compressional and extensional tectonics were probably coeval during the Ross Orogeny. The geological histories also reveal that uplift of the four structural blocks may have occurred at different periods during the Ross Orogeny resulting in a complex interrelation between plutonism and deformation of the Skelton Group. Structural blocks of the type mapped in south Victoria Land can be mapped in north Victoria Land and elsewhere in the Transantarctic Mountains. These blocks preserve results of Ross Orogenic processes at different times and places and at different crustal levels throughout the Transantarctic Mountains. A series of NW striking faults are recognised in north Victoria Land which are related to the same tectonic regime as those NW striking faults identified in south Victoria Land and indicate offset of the Ross Orogen in the Victoria L~nd segment of Antarctica. Neoproterozoic continental rifting in south Victoria Land is younger than that of Windermere rift related metasediments in North America and is not a direct temporal correlative has been suggested in association with the SWEAT hypothesis. Correlation with possible rift events near the Cambrian-Precambrian boundary in North America is also plausible. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/3573">http://hdl.handle.net/10523/3573</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. South Victoria Land Antarctica Thesis description Number of pages, maps, CDs, etc. 502 p. : ill. (some col.), maps (some col.) ; 30 cm. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 1997Cook Creator An entity primarily responsible for making the resource Cook, Yvonne Anne, 1967- Date A point or period of time associated with an event in the lifecycle of the resource 1997 Title A name given to the resource The Skelton Group and the Ross Orogeny : late Neoproterozoic to early Ordovician evolution of South Victoria Land, Antarctica Subject The topic of the resource Map Geochemistry Volcanology geochemistry Ross Orogeny Skelton Group South Victoria Land Volcanology https://theses.otagogeology.org.nz/files/original/ebd563d93c3670ff35c2b981e04d24ac.pdf 99533612e2e0257b0a1270caa9920ce1 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Author last name Last name of the Author Purbawinata Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Coombs, D.S. Abstract The Abstract for this thesis The Guntur-Gandapura Volcanic Complex is part of a cluster of active volcanoes forming a chain in the southern part of West Java, regionally belonging to the western part of the Sunda arc. The Complex, 60 km southeast of Bandung, rises from 700 meters above sea level with Masigit center (2,249 m) being the highest peak and Guntur cone (1,950 m) the most active and the youngest cone of the Complex. The Complex includes the products of fourteen main eruptive centers which have been identified. Geologic evidence from the GGVC suggests that it is very young in age. Eight out of twenty samples analysed for K-Ar dating have usable ages ranging from 0.33±0.02 Ma (Gandapura center) to 0.07±0.03 Ma (Pasir Laku center). Indications related to the K-Ar dating point to the GGVC being younger than 1 Ma, and the initiation of volcanism at the Complex might have occurred no earlier than about 400,000 years ago. Two suites, tholeiitic and calc-alkaline, are represented among the rocks of the Complex. In volume, calc-alkaline andesites are dominant, followed by tholeiitic basalts. Dacites are relatively rare. High-Mg basaltic andesites have the highest magnesium numbers (73-68) among the rocks in the Complex and thus are candidates for primary mantle-derived magmas. There is no definite relationship between the order of eruption and the tholeiitic or calc-alkaline affinities. Eruptions began with either high-Al low-K tholeiites or andesites at the centers which have both tholeiitic and calcalkaline rock types. Texturally, tholeiitic lavas are porphyritic. Plagioclase (An₈₉-An₆₄) phenocrysts are abundant. Olivine and clinopyroxene are less abundant but very significant. Most of the tholeiitic rocks have a typically non-vesicular intergranular groundmass, and some of the rocks have a typically vesicular intersertal groundmass. Tholeiitic scoria of the Complex has a typical vesicular-hypocrystalline groundmass. Texturally, calc-alkaline lavas are porphyritic with abundant plagioclase (An₈₇-An₄₄) and less abundant clinopyroxene, orthopyroxene, olivine, magnetite, and amphibole. Volume of phenocrysts is usually lower than the volume of the groundmass. High-Mg basaltic andesites are less porphyritic with less abundant plagioclase (An₈₀-An₄₅) compared with the 'normal' basaltic andesite (An₈₇-An₆₀). The clinopyroxene from all analysed lavas includes a few clinopyroxenes which have a composition within the diopside field and relatively high Al, especially in the tholeiite lavas. Rims of pigeonite and orthopyroxene surrounding the olivine phenocrysts in tholeiite and basaltic andesite, respectively, suggest that there is a reaction relationship between olivine and liquid producing these Ca-poor pyroxenes. A reconnaissance study of the pyroxene geothermometry shows that if equilibrium were achieved, certain augites in both the high-Mg basaltic andesite and the normal basaltic andesite could have crystallised at temperatures as high as 1150° C. Olivine phenocrysts of high-Mg basaltic andesites are normally zoned from Fo₈₈-₈₉ in the core to Fo₈₄-₈₇ in the rim. It suggests that the phenocryst cores formed by near-liquidus crystallisation with very little or no subsequent fractionation of crystals from the calculated equilibrium liquid, while the olivine phenocryst rims formed by removal of Mg and / or with little subsequent fractionation of crystals from such a liquid. Thus, the olivine of high-Mg basaltic andesites, is of a composition very similar to mantle olivine, and the addition of only 10% of Fo₈₈ or Fo₈₉ will give a total rock composition compatible with direct mantle derivation. On the other hand, the Mg/Mg+Fe²⁺ ratios of the observed tholeiite and normal basaltic andesite might result from cumulus origin from melts of more evolved composition, or partial re-equilibrium of the grains with late-stage liquids having lower Mg/Mg+Fe²⁺ ratios than the bulk rocks. So, it seems unlikely that either of the two olivine-bearing rocks represent unfractionated liquid compositions. The calculated olivine (Fo₈₈) equilibrium temperature for the high-Mg basaltic andesite is about 1208° C. The compositional ulvöspinel components in the titanomagnetite of the tholeiitic lavas are restricted (Usp₃₂-Usp₄₁). Titanomagnetites of basaltic andesites have a wider range of ulvöspinel components from Usp₂₅ to Usp₄₆. Titanomagnetites of andesites and high-Mg basaltic andesites are rather richer in ulvöspinel, 33-56% and 37-46%, respectively, than those of the tholeiite and of most normal basaltic andesites. Magnesian hastingistic hornblende is found in some lavas from the Complex, especially the normal basaltic andesites. The high-Mg basaltic andesites contain both 'microphenocrysts' and inclusions of Cr-rich spinel in olivine. A general absence of the Cr-spinel in the pyroxene or other phases suggests that its crystallisation may have been terminated, or at least restricted, by the time of appearance of the pyroxene phases in the system. Glasses in some tholeiites and basaltic andesites contain micrometer diameter droplets of immiscible high RI, presumably high-Fe glass. The clear high-silica glasses closely resemble the end products of classical magmatic differentiation by crystal fractionation, but intermediate- and low-silica glasses are variable and similar to early silicate melt inclusions in olivines of lunar samples. Petrographic observations suggest that the low-silica glasses are of late origin. These glasses are much lower in iron and are more moderate in silica content than immiscible high-iron glasses from lunar rocks. They have not reached the immiscibility volume where split into silica-rich and iron-rich liquids would normally occur. The Mg-numbers of the tholeiites are mostly too low to be compatible with direct derivation from water-saturated peridotite mantle source, and the trend between silica and Mg-number argues against derivation of the magmas by melting of oceanic basalt sources. The tholeiitic rocks show relatively unfractionated patterns of chondrite-normalised REE with flat patterns of LREE and slightly positive slopes for their HREE. The observed tholeiitic REE patterns and the calculated primary magmas are matched satisfactorily by melting models based on spinel-bearing peridotite sources at approximately twice or three times chondrite levels, provided that degress of partial melting are 10-18%. Fractionation of plagioclase and lesser amounts of olivine and titanomagnetite, with fractionation or addition of clinopyroxene, is capable of explaining the major element variation within the tholeiites of the Complex and can also account for a transition from these to a higher silica basaltic andesite. The geochemistry of the calc-alkaline rocks shows a wide range of composition from 52 to 65% SiO₂, and is more variable in alumina than the tholeiites. The high-Mg basaltic andesites are distinctive in having lower Al₂O₃ than any other rock types in the Complex. The basaltic andesite and andesite are slightly and substantially more enriched, respectively, in their chondrite-normalised LREE. The chondrite-normalised REE patterns of dacites are within the upper range of the andesite patterns. The observed patterns for the Complex calc-alkaline high-Mg basaltic andesite are consistent with 10% melting of amphibole-bearing lherzolite at approximately 4 to 5 times chondrite levels. The andesites and dacites have steeper REE patterns than the basaltic andesites, and are parallel to model curves for 8% melting of amphibole-bearing lherzolite. Source for normal basaltic andesite, andesite, and dacite requires 3 to 4 times chondrite abundances. Fractionation is a possible mechanism in the calc-alkaline magma series to derive the more evolved rocks from the high-Mg basaltic andesite composition. However, the low-K tholeiites cannot be parental to basaltic andesite of the calc-alkaline series. Spidergram analyses for the tholeiitic rocks show that approximately 80% of Ba, Th, and Rb, 60% of Ta and K, 59% and 55% of Sr and Ce, respectively, come from a subduction and/or other additional origin. There is no significant contribution from the subduction zone for Nb, Hf, Zr, Sm, Y, and Yb, and Ti tends to be depleted. Spidergram analyses of the andesites-dacites indicate that large contributions of Th, Rb, Ba, K, Ce, and Ta are of subduction origin. Zr, Hf, and Sm show a small contribution of subduction components. There is no enrichment of P, Y, and Yb, and Ti shows much more depleted patterns than the other incompatible elements. Pre-Guntur tholeiites are relatively low in ⁸⁷Sr/⁸⁶Sr (0.70397 and 0.70392), while the tholeiites of the Guntur cone are slightly higher (0.70417 and 0.70422). These values are higher than typical Indian MORB at an average of 0.70273. The calc-alkaline lavas are higher and have greater variability in ⁸⁷Sr/⁸⁶Sr ratios than the tholeiites. High-Mg basaltic andesites have ⁸⁷Sr/⁸⁶Sr ratios of 0.70436 and 0.70445. Three andesites have ⁸⁷Sr/⁸⁶Sr ratios 0.70433, 0.70456, and 0.70438, and a dacite has 0.70452. The tholeiites of the GGVC might have a similar mantle source to those of the eastern Indian oceanic-floor tholeiites modified by small involvement of the components from the subducted slab. The subducted slab components probably account for the high ⁸⁷Sr/⁸⁶Sr ratios of the more evolved rocks of the Complex. A combination of petrogenetic processes is suggested involving dehydration of the subducted oceanic lithosphere, formation and drag-mechanism of hydrous upper mantle peridotite, enrichment in LIL elements derived from the subducted slab, fractionation, and some magma and crystal re-mixing. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/4536">http://hdl.handle.net/10523/4536 </a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Java Thesis description Number of pages, maps, CDs, etc. vii, 346 p. : col. ill., maps ; 30 cm. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 1990Purbawinata Creator An entity primarily responsible for making the resource Purbawinata, Mas Atje, 1951- Date A point or period of time associated with an event in the lifecycle of the resource 1990 Title A name given to the resource Petrology and geochemistry of the Guntur-Gandapura volcanic complex, West Java, Indonesia Subject The topic of the resource Petrology Guntur Volcano Igneous petrology Indonesia Volcanology