Weedon, Graham P; McCave, I Nick (1991): Grain size distribution of Oligocene and Miocene sediments from the Indus Fan. PANGAEA, https://doi.org/10.1594/PANGAEA.756773, Supplement to: Weedon, GP; McCave, IN (1991): Mud turbidites from the Oligocene and Miocene indus fan at Sites 722 and 731 on the Owen Ridge. In: Prell, WL; Niitsuma, N; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 117, 216-220, https://doi.org/10.2973/odp.proc.sr.117.140.1991
Always quote above citation when using data! You can download the citation in several formats below.
The Owen Ridge south of Oman represents oceanic crust that was uplifted by compressional tectonic forces in the early Miocene. Build-out of the Indus Fan led to deposition of a thick sequence of turbidites over the site of the Ridge during the late Oligocene and early Miocene. Early Miocene uplift of the Ridge led to a pelagic cap of nannofossil chalks. Two short sequences of turbidites from the pre- and syn-uplift phases were chosen for detailed grain size analysis.
The upper Oligocene section at Site 731 is composed of thin (centimeter-decimeter scale) graded mud turbidites separated by relatively thick (decimeter-meter scale) intervals of homogeneous, non-bioturbated clayey siltstones. These finer intervals are unusually silt-rich (about 60%) for ungraded material and were probably deposited as undifferentiated muds from a series of turbidity current tails. By contrast, the lower Miocene section at Site 722 is comprised of a sequence of interbedded turbidites and hemipelagic carbonates. Sharp-based silt turbidites are overlain by burrow-mottled marly nannofossil chalks.
The Oligocene sequence may have accumulated in an overbank setting on the middle fan - the local topographic position favoring frequent deposition from turbidity current tails and occasional deposition from the body of a turbidity flow. Uplift of the Ridge in the early Miocene led to pelagic carbonate deposition interrupted only by turbidity currents capable of overcoming a topographic barrier. Further uplift eventually led to entirely pelagic carbonate deposition.
Median Latitude: 16.546150 * Median Longitude: 59.748900 * South-bound Latitude: 16.470500 * West-bound Longitude: 59.702500 * North-bound Latitude: 16.621800 * East-bound Longitude: 59.795300
Date/Time Start: 1987-09-08T12:00:00 * Date/Time End: 1987-10-09T16:45:00
117-722B * Latitude: 16.621800 * Longitude: 59.795300 * Date/Time Start: 1987-09-08T12:00:00 * Date/Time End: 1987-09-13T10:15:00 * Elevation: -2033.0 m * Penetration: 565.6 m * Recovery: 385.8 m * Location: Arabian Sea * Campaign: Leg117 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 59 cores; 565.1 m cored; 0 m drilled; 68.3 % recovery
117-731C * Latitude: 16.470500 * Longitude: 59.702500 * Date/Time Start: 1987-10-05T13:30:00 * Date/Time End: 1987-10-09T16:45:00 * Elevation: -2371.0 m * Penetration: 994.2 m * Recovery: 59.81 m * Location: Arabian Sea * Campaign: Leg117 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 16 cores; 154.7 m cored; 0 m drilled; 38.7 % recovery
Datasets listed in this publication series
- Weedon, GP; McCave, IN (1991): (Table 1) Grain size distribution for the upper Oligocene section of ODP Hole 117-731C. https://doi.org/10.1594/PANGAEA.756771
- Weedon, GP; McCave, IN (1991): (Table 2) Grain size distribution for the lower Miocene section of ODP Hole 117-722B. https://doi.org/10.1594/PANGAEA.756772