Oceanography and reefs of recent and Paleozoic tropical epeiric seas |
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Authors: | Evan N Edinger St Paul Copper Michael J Risk Warsito Atmojo |
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Institution: | (1) Department of Geography, Memorial University of Newfoundland, A1B 3X9 St. John's Newfoundland, Canada;(2) Department of Earth Sciences, Laurentian University, Ramsey Lake Road, P3E 2C6 Sudbury, Ontario, Canada;(3) School of Geography and Geology, McMaster University, L8S 4M1 Ontario, Hamilton, Canada;(4) Faculty of Fisheries and Marine Science, Diponegoro University, 50241 Semarang, Central Java, Indonesia |
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Abstract: | Summary The Java Sea, one of the few modern tropical epeiric seas, is used as an analogue to examine oceanography, stratigraphy, and
reefs of Devonian strata in the Appalachian and Michigan Basins. Nearshore patch reefs and offshore “pinnacle” reefs occur
in both the Java Sea and the Emsian-Eifelian Onondaga Formation in the Appalachian Basin. Nearshore patch reefs also occur
in the Eifelian Formosa Reef Limestone in the Michigan Basin.
The Java Sea is characterized by quasi-estuarine circulation, in which runoff and rainfall exceed evaporation. Nutrient and
organic matter influx from land and from estuarine upwelling contribute to organic rich facies during transgressions and sea
level highstands. Similarly, we propose that high runoff from the Appalachian Mountains and from the Laurentian craton contributed
to slightly reduced salinity in the Appalachian basin, including possible density stratification during Middle Devonian highstands.
By contrast, the Michigan Basin was characterized by antiestuarine circulation, in which evaporation exceeded combined runoff
and rainfall. Contemporaneous Emsian-Eifelian strata in the Michigan Basin are dolomite and dolomitic limestone, rather than
cherty and muddy limestone typical of the Appalachian basin.
Reef composition generally reflects oceanographic circulation regime within the epicontinental seas we examine. Nearshore
reefs of the modern Java Sea and the Onondaga Formation (Appalachian Basin) are dominated by multilobate submassive, dendroid,
and phaceloid corals, and virtually no platy corals or tabular stromatoporoids. Multilobate and phaceloid corals are better
able to accommodate muddy sedimentation. By contrast, offshore pinnacle reefs of the Java Sea and nearshore reefs of the Formosa
Reef Limestone are dominated by platyAcropora (modern) or tabular and laminar stromatoporoids (Devonian). The scarcity of tabular stromatoporoids, and the dominance of
phaceloid corals and dendritic branching corals, in the Onondaga Formation (Appalachian Basin) are herein explained by localized
high productivity conditions driven by quasi-estuarine circulation, rather than cool water. Quasi-estuarine circulation or
localized topographic upwelling leading to highly productive coastal environments may be responsible for other Paleozoic examples
of apparent cool-water carbonate deposition within the tropics, including the Ordovician of Eastern Canada. |
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Keywords: | Tropical Epeiric Seas Sea Circulation Eutrophication Reefs Sediments Modern Java Sea Appalachian and Michigan Basins Devonian |
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