Submarine volcaniclastic rocks

Fisher, Richard V.

doi:10.1144/gsl.sp.1984.016.01.02

Cited by 88 publications

(33 citation statements)

References 122 publications

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“…Although some workers may incorrectly use the term volcaniclastic apron to loosely refer to any accumulation of sediment around a volcano or chain of volcanoes, the term has been used in a much more rigorous sense by sedimentologists over the past 40 y (Karig and Moore, 1975b;Sample and Karig, 1982;Carey and Sigurdsson, 1984;Farquharson et al, 1984;Fisher, 1984;Busby-Spera, 1985, 1988Cas and Wright, 1987;Smith, 1987;White and BusbySpera, 1987;Houghton and Landis, 1989;Palmer and Walton, 1990;Fisher and Smith, 1991;Fisher and Schmincke, 1994;Smith and Landis, 1995;Orton, 1996;Wright, 1996;Mitchell, 2000;Carey, 2000;Gamberi, 2001;Karátson and Németh, 2001;Allen et al, 2006;Casalbore et al, 2010;Carey and Schneider, 2011). In these papers, a volcaniclastic apron is defined as a thick accumulation of coarse volcanic debris that fringes a volcano or a chain of volcanoes and builds outward from them; volcaniclastic aprons are fan shaped or are composed of coalescing fans that form a wedge.…”

Section: Interpretation Of Depositional Environment At Site U1437: Dementioning

confidence: 99%

Expedition 350 summary

Tamura¹,

Busby²,

Blum³

et al. 2015

Proceedings of the International Ocean Discovery Program

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International Ocean Discovery Program (IODP) Hole U1436A (proposed Site IBM-4GT) lies in the western part of the Izu fore-arc basin, ~60 km east of the arc-front volcano Aogashima, ~170 km west of the axis of the Izu-Bonin Trench, and 1.5 km west of Ocean Drilling Program (ODP) Site 792, at 1776 meters below sea level (mbsl). It was drilled as a 150 m deep geotechnical test hole for potential future deep drilling (5500 meters below seafloor [mbsf ]) at proposed Site IBM-4 using the D/V Chikyu. Core from Site U1436 yielded a rich record of Late Pleistocene explosive volcanism, including a distinctive black glassy mafic ash layer that may record a large-volume subaqueous eruption on the Izu arc front. Because of the importance of this discovery, Site U1436 was drilled in three additional holes (U1436B, U1436C, and U1436D), as part of a contingency operation, in an attempt to get better recovery on the black glassy mafic ash layer and its enclosing sediments and to better constrain its thickness.IODP Site U1437 is located in the Izu rear arc, ~330 km west of the axis of the Izu-Bonin Trench and ~90 km west of the arc-front volcanoes Myojinsho and Myojin Knoll, at 2117 mbsl. The primary scientific objective for Site U1437 was to characterize "the missing half of the subduction factory" because numerous ODP/Integrated Ocean Drilling Program sites had been drilled in the arc-front to fore-arc region (i.e., ODP Site 782A Leg 126), but this was the first site to be drilled in the rear-arc region of the Izu arc. A complete view of the arc system is needed to understand the formation of oceanic arc crust and its evolution into continental crust. Site U1437 on the rear arc had excellent core recovery in Holes U1437B and U1437D, and we succeeded in hanging the longest casing ever in the history of R/V JOIDES Resolution scientific drilling (1085.6 m) in Hole U1437E and cored to 1806.5 mbsf.The stratigraphy at Site U1437 was divided into seven lithostratigraphic units (I-VII) that were distinguished from each other based on the proportions and characteristics of tuffaceous mud/mudstone and interbedded tuff, lapilli-tuff, and tuff-breccia. The section is much more mud rich than expected, with ~60% tuffaceous mud for the section as a whole (89% in the uppermost 433 m) and high sedimentation rates of 100-260 m/My for the upper 1320 m (Units I-V). The proportion (40%) and grain size of volcaniclastics are much smaller than expected for an intra-arc basin, composed half of ash/tuff and half of lapilli-tuff of fine grain size (clasts <3 cm). These volcaniclastics were deposited by suspension settling through water and from density currents, in relatively distal settings. Volcanic blocks are only sparsely scattered through the lowermost 25% of the section (Units VI and VII, 1320-1806.5 mbsf ), which includes hyaloclastite, in situ quench-fragmented blocks, and a rhyolite peperite intrusion (i.e., proximal deposits). The transition from unconsolidated to lithified rocks occurred progressively; however, sediments were consider...

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Section: Interpretation Of Depositional Environment At Site U1437: Dementioning

confidence: 99%

Expedition 350 summary

Tamura¹,

Busby²,

Blum³

et al. 2015

Proceedings of the International Ocean Discovery Program

View full text Add to dashboard Cite

show abstract

“…There can be little doubt that their final depositional environment was marine, as they are interbedded with the turbidites of the Rosroe Formation whose stratigraphy includes thin graptolitic shales and large limestone megaclasts. Many of the quartz crystals in these tuffs exhibit shattering which is common in submarine pyroclastic flows (Fisher 1984). In view of the massive nature of the tuffs it is likely they were deposited by deep-water debris flows.…”

Section: Discussionmentioning

confidence: 99%

Buried oblique‐slip faults in the Irish Caledonides

Williams

2002

Geological Journal

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Despite over a century of geological investigation, the Ordovician evolution of South Mayo, western Ireland, is still imperfectly understood. An example of this is the supposed lateral equivalence of two formations within the succession, the Rosroe and Derrylea Formations of Arenig age, exposed on opposite limbs of a major east-west syncline. These formations exhibit characteristics which suggest that they were not deposited in the same basin. Both formations contain tuff horizons. Geochemical analysis of these tuffs shows that each formation contains chemically distinct volcanic signatures suggesting deposition in separate sub-basins. Previously the Rosroe Formation on the south limb of the syncline was considered the coarse-grained proximal equivalent of the finer-grained Derrylea Formation, both being deposited in a deep-water fan environment. Previously published palaeocurrent data together with new data show the Rosroe Formation to have been derived from the northeast and therefore it cannot be the proximal equivalent of the Derrylea Formation. Additionally, the two formations show different and distinct associations of heavy mineral assemblages.It is suggested that one explanation for these data is that both formations were deposited in separate sub-basins controlled by oblique slip sinistral faults, similar in some respects to the Cenozoic basins of the Gulf of California. In the Irish case these faults would have been largely buried by later Ordovician sedimentation. Some models for the Ordovician evolution of this area postulate the presence of an initial oceanic arc situated above a southward directed subduction zone. The presence of thick proximal submarine tuffs derived from an arc environment in the Rosroe Formation suggest that at least by this time the subduction zone was in fact northward directed and outboard of the arc.

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“…as tholeiitic depleted mantle derivates of Ordovician age (448 +/-145 Ma, Sm-Nd). The abundant amygdales in the basalts proof a maximum extrusion depth of 500 m (FISHER 1984). Furthermore, the depositional features of the acidic pyroclastic rocks point to a shallow marine environment.…”

Section: Aguada De La Perdiz Formationmentioning

confidence: 90%