Pouclet, André; Cambray, Hervé; Cadet, Jean-Paul; Bourgois, Jacques; de Wever, Patrick (1990): Volcanic ash from the Peru continental margin. PANGAEA, https://doi.org/10.1594/PANGAEA.753834, Supplement to: Pouclet, A et al. (1990): Volcanic ash from Leg 112 off Peru. In: Suess, E; von Huene, R; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 112, 465-480, https://doi.org/10.2973/odp.proc.sr.112.167.1990
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During Leg 112 off Peru, volcanic material was recorded from middle Eocene to Holocene time. The petrographical and chemical composition of tephra is consistent with an origin from the Andean volcanic arc. The amount and thickness of ash layers provide valuable evidence for explosive volcanic episodicity. The first indication of volcanism was found in mid-Eocene sediments. Three volcanic pulses date from Miocene time. Two intense episodes took place in upper Pliocene and from Pleistocene to Holocene time. Pliocene-Pleistocene tephra are restricted to the southern upper-slope and shelf sites, indicating a removal of the volcanic arc and the extinction of the northern Peru volcanoes.
The Cenozoic tectonic phases of the Andean margin may be correlated with the Leg 112 volcanic records. The explosive supply of evolved magmatic products succeeded the Incaic and Quechua tectonic phases. Acidic glasses are related to both andesitic and shoshonitic series. The calc-alkaline factor (CAF) of these glasses exhibited moderate magmatic variations during middle and late Miocene time. A dramatic change occurred during the Pliocene-Pleistocene, reflected in a strong CAF increase and the appearance of potassium-rich evolved shoshonitic glasses. This took place when the Nazca Ridge subduction began. This change in the magma genesis and/or differentiation conditions is probably related to thickening of the upper continental plate and to a new configuration of the Benioff Zone.
Median Latitude: -11.222116 * Median Longitude: -78.589590 * South-bound Latitude: -13.480160 * West-bound Longitude: -80.583500 * North-bound Latitude: -8.991500 * East-bound Longitude: -76.891500
Date/Time Start: 1986-10-31T20:30:00 * Date/Time End: 1986-12-18T09:00:00
112-679B * Latitude: -11.063330 * Longitude: -78.272330 * Date/Time Start: 1986-10-31T20:30:00 * Date/Time End: 1986-11-01T07:00:00 * Elevation: -458.0 m * Penetration: 107.2 m * Recovery: 102.99 m * Location: South Pacific Ocean * Campaign: Leg112 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 13 cores; 107.2 m cored; 0 m drilled; 96.1 % recovery
112-679D * Latitude: -11.063830 * Longitude: -78.272170 * Date/Time Start: 1986-11-01T12:45:00 * Date/Time End: 1986-11-02T13:15:00 * Elevation: -462.0 m * Penetration: 245.4 m * Recovery: 116.03 m * Location: South Pacific Ocean * Campaign: Leg112 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 27 cores; 245.2 m cored; 0 m drilled; 47.3 % recovery
112-680A * Latitude: -11.065000 * Longitude: -78.077830 * Date/Time Start: 1986-11-05T07:15:00 * Date/Time End: 1986-11-05T20:30:00 * Elevation: -272.0 m * Penetration: 93.8 m * Recovery: 81.19 m * Location: South Pacific Ocean * Campaign: Leg112 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 10 cores; 93.8 m cored; 0 m drilled; 86.6 % recovery
Datasets listed in this publication series
- Pouclet, A; Cambray, H; Cadet, J-P et al. (1990): (Table 1) Petrographic and chemical features of tephra from the Peru continental margin. https://doi.org/10.1594/PANGAEA.753831
- Pouclet, A; Cambray, H; Cadet, J-P et al. (1990): (Table 2) Chemistry of tephra from the Peru continental margin. https://doi.org/10.1594/PANGAEA.753833