Facies and depositional history of arc-related, deep-marine volcaniclastic rocks in core recovered on International Ocean Discovery Program Expedition 351, Philippine Sea

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Author(s): Johnson, Kyle E.
Source: 90p. Institution: California State University at Northridge, Northridge, CA, United States
Note: In English. Includes appendices. 30 refs. Master's thesis
Summary: The Izu-Bonin-Mariana (IBM) Arc System, south of Japan, hosts a multitude of active and extinct (remnant) volcanic arcs and associated basins partly filled with volcanic sediment. Core extracted adjacent to the proto-IBM arc (Kyushu-Palau Ridge; KPR), in the Amami-Sankaku Basin (ASB) during International Ocean Discovery Program (IODP) Expedition 351, contains an incredibly well-preserved record of backarc sedimentation resulting from changing tectonic regimes during arc development and decline. Approximately 1000 meters of Eocene to Oligocene volcaniclastic sedimentary rocks were analyzed via shipboard core photos, core descriptions, and thin sections with the intention of understanding the depositional history at this site. A database of stratigraphic columns, 539 section and 147 core summaries, was created to display grain size trends, sedimentary structures, bedding characteristics, and facies changes. Individual depositional events were classified using existing and slightly modified classification schemes for muddy, sandy, and gravel-rich gravity flow deposits, as well as muddy deposits and tuffs. Analyzing trends and distributions of depositional unit types indicates how the active depositional systems evolved upsection as the arc matured. Following arc initiation, facies deposited were primarily mud-rich; these coarsened-upward into 12 stacked sequences of submarine lobe and channel facies with sediment from one or more volcanic sources. These are interpreted to represent the building of the arc edifice that began ∼41 Ma. Four distinct periods of coarse lobe accumulation created a thick submarine fan over a period of nearly 13 million years. An abrupt shift to muddy turbidites at ∼30 Ma represents the onset of rifting of the paleo-IBM arc as backarc spreading in the Shikoku Basin was initiated and volcaniclastic supply to the ASB waned with formation of the KPR remnant arc.
Year of Publication: 2016
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Back-arc basins; Basins; Cenozoic; Cores; Depositional environment; Expedition 351; Facies; Grain size; Gravity flows; IODP Site U1438; International Ocean Discovery Program; Island arcs; Izu-Bonin Arc; Lithofacies; Miocene; Neogene; North Pacific; Northwest Pacific; Oligocene; Pacific Ocean; Paleogene; Plate tectonics; Rifting; Sedimentary rocks; Sedimentary structures; Shikoku Basin; Stratigraphic columns; Stratigraphic units; Stratigraphy; Synsedimentary processes; Tertiary; Turbidite; Volcaniclastics; West Pacific
Coordinates: N272300 N272301 E1341907 E1341905
Record ID: 2017034727
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