Provenance, Stratigraphic Architecture, and Hydrogeologic Influence of Turbidites on the Mid-Ocean Ridge Flank of Northwestern Cascadia Basin, Pacific Ocean

• DOI: 10.2110/jsr.2005.012
• Publication Date: 2005-04-11T18:47:49Z
• Authors: M. B. Underwood; K. D. Hoke; A. T. Fisher; E. E. Davis; E. Giambalvo; L. Zuhlsdorff; G. A. Spinelli
• Keywords: Flank; Oceanic basin

Abstract The northwestern edge of Cascadia Basin (North Pacific Ocean) is unusual because late Pliocene to Holocene turbidites lap onto juvenile oceanic crust the Juan de Fuca Ridge. Subsidence ridge flank combines with irregular westward progradation turbidite facies create a stratigraphic section that coarsens and thickens upward. sand provenance mixed. Individual turbidity currents have funneled into area through several shelf–slope abyssal-floor conduits, including Vancouver Valley, Channel, Barkley Canyon, Nitinat Canyon. Local bathymetric blockage, deflection reflection flow paths by basement relief, remobilization intrabasinal submarine slides debris flows, episodic channel switching, sporadic overbank flooding combined produce erratic recurrence intervals for currents. Only tallest highs remained isolated from deposition during last 500,000 years. Spatial temporal differences in sediment accumulation are important they modulate three-dimensional responses compaction consolidation. Those changes physical properties govern where when hydraulic communication underlying shuts down. basal hemipelagic layer transforms an effective hydrologic seal (seepage rates < 1 mm/yr) once sediment–basalt interface buried 100–150 m strata. Rapid turbidites, therefore, accelerates hydrogeologic conversion igneous open sealed.