Predicting diagenetic reaction progress for NanTroSEIZE subduction inputs in the Kumano transect area

Author(s): Spinelli, G. A.; Underwood, M. B.
Author Affiliation(s): Primary:
New Mexico Institute of Mining and Technology, Earth and Environmental Science Department, Socorro, NM, United States
Other:
University of Missouri, United States
Volume Title: AGU 2006 fall meeting
Source: Eos, Transactions, American Geophysical Union, 87( Fall Meeting Suppl.); American Geophysical Union 2006 fall meeting, San Francisco, CA, Dec. 11-15, 2006. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0096-3941 CODEN: EOSTAJ
Note: In English. Accessed on Oct. 16, 2007
Summary: Hemipelagic sediment approaching the Nankai Trough subduction zone displays anomalous physical properties due to a small amount of opal cement. Because the cement inhibits consolidation, sediment at Ocean Drilling Program Sites 1173 and 1177 (upper Shikoku Basin facies) has anomalous porosity, seismic velocity, and rigidity. At the base of the cemented section, there is a step decrease in porosity. Numerical models of opal-CT content display increases with depth through the cemented section. With increasing temperature, the rate of opal-CT dissolution outpaces precipitation, the cement can no longer support the overburden, and the open framework of the sediment begins to collapse. The weakening is consistent with loss of shear rigidity and anomalous seismic velocities. We have modeled the sediment accumulation and thermal histories of five proposed drilling sites seaward of the Kumano Basin and Nankai Trough; the sites are part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE). We use a transient 1-D model to simulate sediment accumulation, consolidation, temperature, opal diagenesis, and cementation. Modeling shows how differences in sediment accumulation rate and basal heat flux affect the depth of the opal-quartz diagenetic front. At sites with higher sediment accumulation rates, the modeled opal-quartz diagenetic front shifts deeper below the seafloor, as compared to condensed sections above basement highs. This shift results from the reduced time for opal-to-quartz reaction to proceed prior to the sediment reaching any given burial depth.
Year of Publication: 2006
Research Program: ODP Ocean Drilling Program
Key Words: 06 Petrology, Sedimentary; Burial; Cementation; Diagenesis; Framework silicates; Hemipelagic environment; Kumano Basin; Leg 190; Marine environment; Marine sedimentation; Marine sediments; NanTroSEIZE; Numerical models; ODP Site 1173; ODP Site 1177; Ocean Drilling Program; Opal; Opal-CT; Porosity; Quartz; Sedimentation; Sediments; Silica minerals; Silicates; Subduction zones; Thermal history
Coordinates: N321500 N321500 E1350200 E1350200
N313900 N314000 E1340100 E1340000
Record ID: 2009096211
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