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21 pages, 12062 KiB

Open AccessEditor’s ChoiceArticle

The Suitability of the Pacific Islands for Harnessing Ocean Thermal Energy and the Feasibility of OTEC Plants for Onshore or Offshore Processing

by Hyeon-Ju Kim, Ho-Saeng Lee, Seung-Taek Lim and Michael Petterson

Geosciences 2021, 11(10), 407; https://doi.org/10.3390/geosciences11100407 - 27 Sep 2021

Cited by 15 | Viewed by 4918

Abstract

Ocean Thermal Energy Conversion (OTEC) relies on the thermal differences between ocean surface waters and cooler waters at c. 1000 m depth. The highest and most reliable thermal differentials are in the low latitudes, 20° either side of the equator, including the Pacific [...] Read more.

Ocean Thermal Energy Conversion (OTEC) relies on the thermal differences between ocean surface waters and cooler waters at c. 1000 m depth. The highest and most reliable thermal differentials are in the low latitudes, 20° either side of the equator, including the Pacific Islands region. Whilst in theory OTEC can utilize an inexhaustible amount of stored energy within the oceans, in practice the industry remains in its technical infancy, but with an increasing relevance to a post-fossil-fuel, environmentally conscious world. OTEC does not only produce electricity. OTEC-seawater utilization technologies produce high demand ocean minerals, desalination, a range of waters for aquaculture and hydroponics, and have the potential to produce large quantities of green hydrogen. OTEC is a green energy and could revolutionize the energy and economic landscape of Pacific island countries, providing reliable low-C electricity and a basis for a range of industry. This paper analyses the economics of using OTEC in combination with existing and potential future industries of importance to the Pacific (and other oceanic) regions, including tuna fisheries, seabed minerals and green hydrogen. The conclusions of these analyses suggest that OTEC has the potential to minimize carbon emissions, increase efficiencies, and create new high-quality green-technology industries and livelihoods. Full article

(This article belongs to the Special Issue The Geoscience of the Pacific Islands Region: Theory and Practice)

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20 pages, 4871 KiB

Open AccessArticle

Securing the Limits of Large Ocean States in the Pacific: Defining Baselines Limits and Boundaries amidst Changing Coastlines and Sea Level Rise

by Leonardo Bernard, Michael Petterson, Clive Schofield and Stuart Kaye

Geosciences 2021, 11(9), 394; https://doi.org/10.3390/geosciences11090394 - 17 Sep 2021

Cited by 5 | Viewed by 3683

Abstract

The Pacific Island States and Territories are traditionally described as ‘small island’ nations. However, they are also ‘large ocean’ nations with jurisdiction over substantial maritime spaces stretching to at least 200 nautical miles. The article addresses issues related to baselines along the coast [...] Read more.

The Pacific Island States and Territories are traditionally described as ‘small island’ nations. However, they are also ‘large ocean’ nations with jurisdiction over substantial maritime spaces stretching to at least 200 nautical miles. The article addresses issues related to baselines along the coast on which these broad maritime claims depend. The article then examines geodynamic considerations coupled with sea and land level projections in the Pacific leading to an assessment of the vulnerability or resilience of atolls in particular. The article then discusses potential implications for the coastlines and baselines of the Pacific Island States and Territories, the limits of their maritime entitlements and both delimited and undelimited maritime boundaries. Potential response options, prospects, and concluding thoughts are then offered. Full article

(This article belongs to the Special Issue The Geoscience of the Pacific Islands Region: Theory and Practice)

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29 pages, 7774 KiB

Open AccessArticle

Why Disaster Subcultures Matter: A Tale of Two Communities: How and Why the 2007 Western Solomon Islands Tsunami Disaster Led to Different Outcomes for Two Ghizo Communities

by Kim Hagen, Michael G. Petterson, David Humphreys and Nigel Clark

Geosciences 2021, 11(9), 387; https://doi.org/10.3390/geosciences11090387 - 11 Sep 2021

Cited by 4 | Viewed by 3429

Abstract

At 07:45 a.m. on 2 April 2007, a tsunami hit Ghizo Island, western Solomon Islands in the south-west Pacific. Thirty-three people died on Ghizo, of whom 31 originated from a relatively small migrant Gilbertese community (transmigrated in the 1950s–1970s from Kiribati), while only [...] Read more.

At 07:45 a.m. on 2 April 2007, a tsunami hit Ghizo Island, western Solomon Islands in the south-west Pacific. Thirty-three people died on Ghizo, of whom 31 originated from a relatively small migrant Gilbertese community (transmigrated in the 1950s–1970s from Kiribati), while only two were from the majority Melanesian community. This paper documents an extensive 4-year study that addresses the potential core reasons for this asymmetrical casual impact. Community-participatory social science research was undertaken in two Gilbertese villages and two Melanesian villages. The four villages had similar spatial vulnerabilities due to their coastal location, although they had variable access to the safer higher ground. Gilbertese villages had less diverse ocean-reliant livelihoods, a limited knowledge of hinterland bush resource utilisation, uncertainties regarding land rights, and perceived ethnic discrimination. Melanesian villages had strong wantok and kastom social reciprocity cultures, a diverse set of livelihoods, wider social capital with other Melanesian communities, and greater security regarding land rights. This paper argues that these key factors—linked to the lower status as a migrant community of the Gilbertese, a limited sharing of knowledge between communities, government blind spots and power hierarchies—explain both the disproportionate impacts of the disaster and issues that impact longer-term aid intervention and social cohesion. Full article

(This article belongs to the Special Issue The Geoscience of the Pacific Islands Region: Theory and Practice)

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38 pages, 95091 KiB

Open AccessArticle

Trace Element Geochemistry of Chalcopyrites and Pyrites from Golpu and Nambonga North Porphyry Cu-Au Deposits, Wafi-Golpu Mineral District, Papua New Guinea

by Moira Lunge and Joseph O. Espi

Geosciences 2021, 11(8), 335; https://doi.org/10.3390/geosciences11080335 - 9 Aug 2021

Viewed by 3413

Abstract

Studying elemental geochemistry of hypogene sulphides can discriminate the hydrothermal fluids responsible for ore formation. To determine whether Golpu porphyry Cu-Au deposits are related to the Nambonga North porphyry system which is located 2.5 km apart in the Wafi-Golpu Mineral District, Papua New [...] Read more.

Studying elemental geochemistry of hypogene sulphides can discriminate the hydrothermal fluids responsible for ore formation. To determine whether Golpu porphyry Cu-Au deposits are related to the Nambonga North porphyry system which is located 2.5 km apart in the Wafi-Golpu Mineral District, Papua New Guinea, we compare the trace element compositions of drill core chalcopyrites and pyrites analysed using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS). The results for the Golpu chalcopyrites revealed high concentrations of Au, As, Se, Mo, Sb, Te and Bi and lower concentrations of Ag and Zn compared to those from Nambonga. Pd and Pt were below the detection limit in chalcopyrites for both deposits. The results for the Golpu pyrites indicated high concentrations of Pt, Au, Se, Mo, Sb, and Te and lower concentrations of Cu, Zn, As, Ag, Pb, Pd and Bi compared to those from Nambonga North. Au concentrations in the pyrites from both the porphyry deposits were higher compared to chalcopyrites, which mean that pyrite is the Au-bearing sulphide responsible for the higher Au content. In contrast, Cu values in pyrites from Nambonga North are higher than those from Golpu. Overall, it is envisaged that the ore fluids were exsolved at different times during the evolution of both porphyry deposits, although these porphyry centres may be related in space and time. Full article

(This article belongs to the Special Issue The Geoscience of the Pacific Islands Region: Theory and Practice)

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16 pages, 6388 KiB

Open AccessArticle

Stream Sediment Datasets and Geophysical Anomalies: A Recipe for Porphyry Copper Systems Identification—The Eastern Papuan Peninsula Experience

by Nathan Mosusu, Angela Bokuik, Michael Petterson and Robert Holm

Geosciences 2021, 11(7), 299; https://doi.org/10.3390/geosciences11070299 - 20 Jul 2021

Cited by 2 | Viewed by 4435

Abstract

Airborne magnetic and radiometric datasets have, over the past few years, become powerful tools in the identification of porphyry systems which may host economic porphyry copper–gold–molybdenum ore bodies. Magnetisation contrasts with the unaltered host rocks, coupled with the elevated radiometric signature, compared to [...] Read more.

Airborne magnetic and radiometric datasets have, over the past few years, become powerful tools in the identification of porphyry systems which may host economic porphyry copper–gold–molybdenum ore bodies. Magnetisation contrasts with the unaltered host rocks, coupled with the elevated radiometric signature, compared to the host rock, makes identification of large-scale porphyry copper systems possible. Integrating these two different datasets with stream sediment data and other geochemical exploration methods results in a higher degree of confidence. Stream sediment data were analysed to see the distribution of copper and gold elements throughout the study area, located within the Eastern Papuan Peninsula of Papua New Guinea. Airborne geophysics data over the same area were also processed for magnetic and radiometric responses. The processing of the magnetic data revealed several magnetic anomalies related to concealed intrusive rock units, with associated radiometric signatures. The distribution of gold and copper anomalism was correlated with the geology and geophysical signatures. Results indicate varying degrees of correlation, with some areas showing a strong correlation between gold/copper occurrence and geophysical signatures, compared to other areas. Some factors that we believe impact the level of correlation may include tectonic history, volcanic cover, and weathering patterns. We recommend caution when applying multi-data exploration for porphyry copper systems. Full article

(This article belongs to the Special Issue The Geoscience of the Pacific Islands Region: Theory and Practice)

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11 pages, 6995 KiB

Open AccessArticle

Identifying 3000-Year Old Human Interaction Spheres in Central Fiji through Lapita Ceramic Sand-Temper Analyses

by Roselyn Kumar, Patrick D. Nunn and Elia Nakoro

Geosciences 2021, 11(6), 238; https://doi.org/10.3390/geosciences11060238 - 31 May 2021

Cited by 2 | Viewed by 3633

Abstract

Petrographic analyses of sand tempers in Pacific Island potsherds reveal information about ancient human interactions within archipelagic contexts. By comparison with bedrock mineralogy, analyses of 45 sherds from the Lapita settlement at Naitabale on Moturiki Island (central Fiji) show that most sherds were [...] Read more.

Petrographic analyses of sand tempers in Pacific Island potsherds reveal information about ancient human interactions within archipelagic contexts. By comparison with bedrock mineralogy, analyses of 45 sherds from the Lapita settlement at Naitabale on Moturiki Island (central Fiji) show that most sherds were manufactured locally but that a minority is exotic. Using ternary plots of LF-QF-FM (LF—lithic fragments; QF—quartz + feldspar; FM—ferromagnesian), it is shown that exotic material (either pots or temper sands) most likely came from elsewhere in Fiji, probably southeast Viti Levu Island, central Lau, Lomaiviti and Kadavu. Geoscientific analyses of archaeological samples therefore gives us insights into how people likely interacted within the Fiji Archipelago three millennia ago. Full article

(This article belongs to the Special Issue The Geoscience of the Pacific Islands Region: Theory and Practice)

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15 pages, 4171 KiB

Open AccessArticle

O cei na Vulavula? Insights and Regrets of a Foreign Geoscientist in the Pacific Islands

by Patrick D. Nunn

Geosciences 2021, 11(5), 182; https://doi.org/10.3390/geosciences11050182 - 22 Apr 2021

Cited by 2 | Viewed by 6084

Abstract

From over three decades of close contact with Pacific Islands geoscience, the author reflects on key issues (what he wished he had known earlier) about the nature of islands, their landscapes and their peoples. Experience elsewhere in the world rarely prepares you for [...] Read more.

From over three decades of close contact with Pacific Islands geoscience, the author reflects on key issues (what he wished he had known earlier) about the nature of islands, their landscapes and their peoples. Experience elsewhere in the world rarely prepares you for the Pacific, from its youthful and often tectonically unstable landscapes to the understandings of its inhabitants, which are sometimes time-consuming and difficult to access yet frequently illuminating. Mysteries abound in Pacific geoscience, often in places as difficult to access as they ever were, yet which have the potential to inform global ideas about earth-surface evolution. Geoscience research and enterprise remain largely foreigner-driven in the Pacific Islands, which is often anathemic to sustainability, privileging ideas that are uncritically assumed to be shared by their peoples. An opportunity exists for Pacific peoples to own the geoscientific knowledge and potential of their islands. Full article

(This article belongs to the Special Issue The Geoscience of the Pacific Islands Region: Theory and Practice)

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Review

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37 pages, 5653 KiB

Open AccessEditor’s ChoiceReview

The Shape of Fluvial Gravels: Insights from Fiji’s Sabeto River

by S. J. Gale

Geosciences 2021, 11(4), 161; https://doi.org/10.3390/geosciences11040161 - 1 Apr 2021

Cited by 4 | Viewed by 3887

Abstract

This project aims to re-assess our understanding of the shape of fluvial bedload gravels by drawing together existing information on fluvial gravel shape. At its crux, however, is the interpretation of a large, high-quality set of measurements made on bedload gravels from the [...] Read more.

This project aims to re-assess our understanding of the shape of fluvial bedload gravels by drawing together existing information on fluvial gravel shape. At its crux, however, is the interpretation of a large, high-quality set of measurements made on bedload gravels from the Sabeto River of western Viti Levu, Fiji. This work reveals that the apparent simplicity displayed by most studies of downstream rounding disguises a complex pattern of stepwise reversals to an angular state, the result of the splitting of cobble- and boulder-sized particles. Particle sphericity changes rapidly during the initial stages of transport. Along the Sabeto, this seems to be the result of attrition, with breakage generating the low and continuing presence of low sphericity particles in the system. Elsewhere, however, sphericity is a consequence of shape sorting and we speculate that rivers globally exist along a sorting–attrition continuum. The form of fluvial gravels is not what would be expected were sorting the dominant control on gravel form. Instead measurements of form display a complex relationship with roundness (and thus with breakage and abrasion). Fluvial gravels appear to evolve to a distinctive shape that may offer a means of distinguishing the products of riverine deposition. Full article

(This article belongs to the Special Issue The Geoscience of the Pacific Islands Region: Theory and Practice)

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