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Drowned reefs and antecedent karst topography, Au'au channel, S.E. Hawaiian Islands

Coral Reefs

By:
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DOI: 10.1007/s00338-001-0203-8

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Abstract

During the last glacial maximum (LGM), about 21,000 years ago, the Hawaiian Islands of Maui, Lanai, and Molokai were interconnected by limestone bridges, creating a super-island known as Maui-Nui. Approximately 120 m of sea-level rise during the Holocene Transgression flooded, and then drowned, these bridges separating the islands by inter-island channels. A new multibeam high-resolution bathymetric survey of the channels between the islands, coupled with observations and video-transects utilizing DeepWorker-2000 submersibles, has revealed the existence of numerous drowned reef features including concentric solution basins, solution ridges (rims), sand and sediment plains, and conical-shaped reef pinnacles. The concentric basins contain flat lagoon-like bottoms that are rimmed by steep-sided limestone walls. Undercut notches rim the basins at several depths, marking either sea-level still stands or paleo-lake levels. All of the solution basins shallower than 120 m were subaerial at the LGM, and at one stage or another may have been shallow shoreline lakes. Today, about 70 drowned reef pinnacles are scattered across the Maui-Lanai underwater bridge and all are situated in wave-sheltered positions. Most drowned during the interval between 14,000 and 10,000 years ago when sea-level rise averaged 15 mm/year. Virtually all of the surficial topography in the Au'au Channel today is a product of karst processes accentuated by marginal reef growth during the Holocene. Both the submerged basins and the drowned reefs represent an archive of sea-level and climate history in Hawaii during the late Quaternary.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Drowned reefs and antecedent karst topography, Au'au channel, S.E. Hawaiian Islands
Series title:
Coral Reefs
DOI:
10.1007/s00338-001-0203-8
Volume
21
Issue:
1
Year Published:
2002
Language:
English
Contributing office(s):
Coastal and Marine Geology Program
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
73
Last page:
82
Number of Pages:
10
Country:
United States
State:
Hawai'i
Other Geospatial:
Au'au Channel