M.S. - Geology and Geophysics

Permanent URI for this collectionhttps://hdl.handle.net/10125/2068

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Petrology, geochemistry, and ages of volcanic rocks from the Line Islands, Central Pacific Ocean
(University of Hawaii at Manoa, 1986) Davis, Geoffrey Trevor; Geology and Geophysics (Volcanology, Petrology and Geochemistry)
The Line Islands chain is a major linear volcanic feature on the Pacific plate which, when combined with the Tuamotu Archipelago and the Gambier Islands, extends for over 6000 km from the Mid-Pacific Mountains southeast to Pitcairn Island, a recently acti
Hydrogeochemistry of a small limestone-island: Laura, Majuro Atoll, Marshall Islands
(University of Hawaii at Manoa, 1987) Anthony, Stephen S.; Geology and Geophysics
The isolated atoll of Majuro is an ideal location to apply a hydrogeochemical approach to the occurrence and movement of groundwater in an island aquifer system. Majuro is typical of many atolls throughout the Pacific. It exhibits calcareous atoll geology
Petrology of the phosphates on Tuvuca, Fiji
(University of Hawaii at Manoa, 1982) Lee, Annabelle Inn Ngue; Geology and Geophysics
Phosphatic pelletal packstones and grainstones were collected from Tuvuca, Fiji, an island in the northern section of the Lau Islands. The deposits occur within cavities and fractures in the limestone, which is Futuna Limestone of middle Miocene to possib
A magnetotelluric investigation of the electrical conductivity of the upper mantle beneath Midway Island
(University of Hawaii at Manoa, 1981) Thomas, Tommie Lee; Geology and Geophysics
The magnetotelluric response functions for one month of data from Midway Island have been modelled by one-dimensional structures of varying complexity after removal of the island effect. These models reveal an anomalous zone of conductivity between .8 and
Crustal structure of the Mariana Trough from seismic refraction data
(University of Hawaii at Manoa, 1980) Ambos, Elizabeth L.; Geology and Geophysics
Three seismic refraction profiles were shot in the Mariana Trough in the vicinity of the proposed axial rift spreading center. One long east-west trending line was shot across the axial high region, the elevated portion of the Trough associated with the r
Crustal structure of the Mariana Island arc system and old Pacific plate from seismic refraction data
(University of Hawaii at Manoa, 1978) LaTraille, Sharon L.; Geology and Geophysics
Twenty-six new explosion refraction profiles from the Mariana island arc system and old Pacific plate along a 750 km east-west line at about 18°N latitude are analyzed to determine crustal structure across the Mariana basin (old Pacific plate ), arc-trench gap, Mariana ridge and Mariana trough. The Pacific plate east of the Mariana trench has a crustal thickness of 6.8 km, similar to that of average Pacific ocean crust, but has thicker than average layers 2A and 2B. This is most likely due to lower velocity material introduced by local seamount volcanism. Large scale vertical faulting in the arc-trench gap is supported by the data in this study, while plate accretion is not. Thick sequences of low-velocity material are also found in the arc-trench gap, and no mantle velocities are found. Crustal structure on the Mariana ridge is roughly similar to that of the arc-trench gap. There is evidence here of arrivals from a relatively high velocity body under the ridge, possibly a volcanic plug or sill. In the Mariana trough, an average crustal thickness of S km is found, with evidence of crustal thinning toward the center of the trough. These data, together with depth-age and depth-heat flow relationships, indicate crustal formation in the Mariana marginal basin differs considerably from that at mid-ocean ridges. Crust which forms in the marginal basin is thinner, cools faster and sinks more quickly than oceanic crust.
The accuracy of charted port positions in the Pacific as defined by satellite determined positions using multiple observations
(University of Hawaii at Manoa, 1977) Hanna, Valerie M.; Geology and Geophysics
As a by-product of the marine scientific program on the oceanographic cruises of the University of Hawaii's research vessels, positions for 34 dock or anchorage sites in and around the Pacific basin were determined using the Magnavox 702 CA (MX 702/hp) Satellite Navigator as a fixed point positioning device. While it is apparent that not all positions were determined to the same accuracy, a significant number represent improvements of 15 seconds or more in the charted positions of islands, ports and harbors in the Pacific basin. Thus this work may prove to be of considerable benefit by establishing a network of well known and well surveyed Doppler determined positions in the Pacific which may serve as geodetic position references. More fundamentally, this study will contribute to the safety of navigation in making land approaches by providing more modern and accurate positional information than can be obtained from charts.
The structure of the Mariana arc as inferred from gravity and seismic data
(University of Hawaii at Manoa, 1979) Sager, W. W.; Geology and Geophysics
A two dimensional gravity model of the lithosphere was constructed along a seismic refraction line, 800 km in length, across the Mariana arc near l8°N latitude. Included in the model are crustal layers constrained by seismic refraction results, an estimat
A seismic study of the crustal structure of the Ontong Java Plateau and Nauru Basin
(University of Hawaii at Manoa, 1978) Halada, Richard S.; Geology and Geophysics
In May, 1976 seismic refraction measurements were made across the northern Ontong Java Plateau and Nauru Basin by the R/V KANA KEOKI. Forty sonobuoys were deployed and data were obtained along a 930 km line. The purpose of this study was to better define
Ita Mai Tai Guyot: a comparative geophysical study of western Pacific seamounts
(University of Hawaii at Manoa, 1985) Wedgeworth, Bruce Steven; Geology and Geophysics
Ita Mai Tai is a large, uncompensated seamount on the eastern edge of the East Mariana Basin. A large positive gravity anomaly of 254 mgal characterizes the summit and a low of -69 mgal, the surrounding moat. Using polygonal prisms to approximate the bath
Sedimentation processes in the northern Melanesian borderland
(University of Hawaii at Manoa, 1983) Wirasantosa, Sugiarta; Geology and Geophysics
Sediment distribution and sedimentation processes in the northern Melanesian borderland were studied using 3.5 kHz echograms, seismic reflection profiles, unreversed sonobuoy seismic refraction profiles, and core samples. A sediment isopach map shows thic
Petrology and tectonic evolution of seamounts and banks of the Northern Melanesian Borderland, Southwest Pacific
(University of Hawaii at Manoa, 1983) Johnson, Kevin Todd Michael; Geology and Geophysics
Petrologic study of volcanic rocks dredged from seamounts, banks, and islands of the Northern Melanesian Borderland (NMB) reveals several distinct provinces. Taviuni-Field, Lalla Rookh, and Combe Banks l ie on an azimuth approximately paral lel to Paci f
Geology of the eastern Central Pacific Basin
(University of Hawaii at Manoa, 1975) Orwig, Thedore L.; Geology and Geophysics
A geological investigation of the eastern Central Pacific Basin, and its eastern boundary, the Line Islands Ridge, has been completed. Detailed analysis of bathymetric, magnetic, and continuous seismic reflection data was supplemented by piston core studi
Foraminiferal isotopic and assemblage analysis across the Epoch 6 Carbon Shift, western equatorial Pacific
(University of Hawaii at Manoa, 1987) Lauritzen, Robert a; Geology and Geophysics
The results of a detailed isotopic and faunal analysis of foraminifera across the Epoch 6 Carbon Shift at DSDP Site 62.1 are presented ∂18O, ∂13C, and frequency data for the planktonic foraminifer Streptochilus show a shallowing and intensification of the
Heat flow in the western equatorial Pacific Ocean
(University of Hawaii at Manoa, 1972) Halunen, Arlie John; Geology and Geophysics
Eighty-eight previously unpublished measurements are added to our knowledge of heat flow in the western equatorial Pacific Ocean. The mean of 32 values obtained between the Line Islands and the Marshall, Gilbert, and Ellice island groups is 1.15 ± 0.06 (s
Petrology and geochemistry of some rock samples from the northern Fiji Plateau
(University of Hawaii at Manoa, 1973) Fryer, Patricia; Geology and Geophysics
Samples were collected from Anuda and Tikopea, two islands on the northern part of the Fiji Plateau, not previously investigated by geologists; samples were also dredged from the southwest wall of the Vitiaz Trench. Although the mineralogy and petrology o
Recent benthic foraminifera of the Ontong Java Plateau
(University of Hawaii at Manoa, 1977) Culp, Susan Kay.; Geology and Geophysics
Analysis of the recent benthic foraminifera from the Ontong Java Plateau and surrounding areas of the Western Equatorial Pacific revealed 167 different species. Using factor analysis, four factors were found which accounted for 47.5 percent of the variabi
Pacific stress patterns and possible stress transmission
(University of Hawaii at Manoa, 1978) Carter, Jerry A.; Geology and Geophysics
Using the Gutenberg - Richter relation log N = a - bM, patterns of stress variation (in terms of variation of "b") for several areas around the Pacific are compared to test the possibility of stress transmission through lithospheric plates. Periods of six
Exploration For Blind Geothermal Resources In The State Of Hawaiʻi Utilizing Dissolved Noble Gasses In Well Waters
(University of Hawaii at Manoa, 2020) Ferguson, Colin Mikael; Rowland, Scott K.; Geology and Geophysics
This study is an extension of the Hawaii Play Fairway Analysis (PFA), a statewide geothermal exploration project funded by the United States Department of Energy. Based on results from prior phases of the PFA, this project targeted 66 wells on the islands of Hawai‘i, Maui, Lānaʻi, Oʻahu, and Kauaʻi for sampling of dissolved noble gases, trace metals, common ions, and the stable isotopes 2H and 18O. Ultimately, 23 of the 66 well targets were sampled. Noble gas data from this study is supplemented with data shared by the United States Geologic Survey for the summit of Kīlauea, and by the geothermal energy company Ormat Technologies Inc. for their geothermal power plant Puna Geothermal Venture on the Lower East Rift of Kīlauea, and for their exploration of Kona and Hualālai on Hawaiʻi, as well as the Southwest Rift of Haleakalā on Maui. The noble gas helium is used as an indicator of geothermal heat when excess 3He and/or 4He is present when compared to the atmospheric ratio of those isotopes (R/Ra). R/Ra is minimally affected by dilution and transport, allowing even those wells not perfectly situated over a geothermal system to indicate a geothermal anomaly. R/Ra anomalies are present on every island in this study. There is a strong correlation between R/Ra anomalies and proximity to rift zones and calderas. Across the islands R/Ra ranged from 15-16 on Kīlauea’s lower east rift zone, which is a mantle plume value, to 0.37 on Lāna‘i, which is a crustal value. The majority of anomalous well samples had R/Ra values consistent with an upper mantle source. Mixing between upper mantle and crustal helium is evident on all islands. Geographically, R/Ra decreases from the high at Kīlauea to upper mantle values at Mauna Loa, and remains at upper mantle values for all wells across the other volcanoes, with the exception of two of four sampled wells on Lānaʻi, which have radiogenic, crustal R/Ra values (<1). The trend of steeply decreasing R/Ra spatially, from plume-like to upper-mantle values, and then relatively constant values to Kaua‘i is consistent with fluid transport in the upper mantle in the direction of plate motion, and migration of noble gases into that fluid reservoir. Due to the association of helium with heat, it is likely that geothermal resources of undetermined potential are present on most Hawaiian Islands.
Investigating Volcanic Eruptions at the Seamount Tafu: Chemical and Geographic Variation Within the NELSC
(University of Hawaii at Manoa, 2020) Zinn, Malia Christine; Rubin, Kenneth H.; Geology and Geophysics
Most eruptions on Earth are likely submarine (Rubin et al., 2012); however, relatively little is known about deep-sea eruptions due to the difficulty in detecting and observing them. The Northeast Lau Spreading Center (NELSC) in the Northeast Lau Basin is an excellent location to study these deep-sea processes, as it is one of the most volcanically active submarine provinces on Earth. This thesis presents reports on three known eruptions that occurred at the NELSC seamount Tafu between 2006 and 2017 and compares them to a 2008 eruption that occurred at Tafu’s next-ridge neighbor, Puipui (Baker et al., 2011). The new Tafu eruption deposits were identified by bathymetric changes of up to 100m between repeated multibeam sonar surveys conducted over the past two decades. The Schmidt Ocean Institute cruise FK171110 set out in 2017 to investigate the Northeast Lau Basin using both autonomous underwater vehicle (AUV) and ship-based bathymetric mapping. During this cruise, the remotely operated vehicle SuBastian conducted several dives, including two at the NELSC: one on Tafu’s north flank, and one on Tafu’s south flank. Photos and videos were taken throughout the dive, and rock and sediment samples were collected. This study investigates the geochemistry, petrology, and morphology of samples collected, and how this relates to the locations in which they were emplaced. Pairing observations made from photo/video evidence from the dives with both electron microprobe analysis and Raman microscopy allows for reconstruction of magma formation history and eruption conditions.

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