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COASTAL EVOLUTION OF PACIFIC ISLANDS IN RESPONSE TO SEA LEVEL CHANGE DURING THE MID-HOLOCENE

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Title:COASTAL EVOLUTION OF PACIFIC ISLANDS IN RESPONSE TO SEA LEVEL CHANGE DURING THE MID-HOLOCENE
Authors:KANE, HAUNANI HIILANI
Contributors:Fletcher, Charles H. (advisor)
Geology and Geophysics (department)
Keywords:Marine geology
Climate change
Sedimentary geology
atoll
foraminifera
show 4 morePacific Islands
sea level rise
sedimentology
Stratigraphy
show less
Date Issued:2019
Publisher:University of Hawai'i at Manoa
Abstract:Understanding the timing and influence of past examples of sea level change is important for discerning coastal sediment dynamics, interpreting early human migration and guiding decision making related to future sea level rise (SLR). The mid-Holocene sea level highstand is now well documented across the equatorial Pacific, with peak sea level values ranging from 0.25-3.00 m above present mean sea level between 1,000-5,000 yr BP. Interpretations of the composition and age of buried island sediment and fossil reefs were used to characterize the response of high volcanic islands and low lying atolls to sea level change.
At eastern ʻUpolu, a volcanic high island in Sāmoa (Chapter 2) we find that a sea level fall of 0.3-1.0 m, approximately 1899–2103 cal yr BP (calendar years before present), triggered the burial of the fossil beach as the coastal plain expanded towards the sea. A millennium of coastal plain development was further required before post mid-Holocene drawdown in regional sea level produced coastal settings that were morphologically attractive for human settlement.
In Chapter 3, a 5,000 year record of ecosystem response to mid- to late- Holocene sea level change is interpreted from fossil-reef cores and island sediment at Majuro atoll. Emergence of a foraminifera dominant atoll reef-island required (1) the formation of a low porosity, limestone platform by reef-flat infilling and diagenesis, and (2) sea level regression and decreased hydrodynamic energy to activate a highly productive Calcarina foraminifer dominated reef-flat.
Chapter 4 couples the geologic record and future projections of SLR to derive place based sea level thresholds and time frames to anticipate rapid island evolution in response to future SLR within the Republic of the Marshall Islands. Under all sea level projections reef-islands will actively evolve within this century as SLR exceeds threshold values conducive with former island building. Impacts are further expedited due to loss of potable groundwater, accelerating SLR, and infrastructure damage. SLR threatens the cultural identify of atoll nations and as such will require adaptable planning methods, reflective of multidisciplinary research, and open minded, multi-world views.
Description:Ph.D. Thesis. Ph.D. Thesis. University of Hawaiʻi at Mānoa 2019
Pages/Duration:123 pages
URI:http://hdl.handle.net/10125/63187
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Ph.D. - Geology and Geophysics


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