Provenance and dispersal of muds south of the Aleutian arc, north Pacific Ocean

Abstract

X-ray diffraction analyses show that the clay mineralogies of nearsurface muds in the Gulf of Alaska (mostly illite and chlorite) are consistent with detrital sources in southern Alaska. Expandable clay minerals arc derived from the Aleutian volcanic arc, and their percenlages increase progressively toward the west. Smectite values are lower than expected, however, particularly in the central forearc, and there is less smectite on the insular trench slope than farther seaward. The regional clay-mineral distribution is controlled by two opposed contour currents and by the influx of suspended sediment via both transverse and trench-axis turbidity currents.

Modern modes of provenance and dispersal of terrigenous sediments in the North Pacific and Bering Sea: implications and perspectives for palaeoenvironmental reconstructions

“…High smectite contents point to local sources from altered volcanic rocks of the Aleutian Arc and Kamchatka (Underwood and Hathon 1989;Hathon and Underwood 1991;Naidu et al 1995). Nonetheless, the relatively high contents of chlorite indicate admixtures of local with more distal materials from Alaska, consistent with tongue-shaped chlorite maxima through some passages of the discontinuous barrier of the Aleutian arc.…”

“…In the North Pacific and adjoining Bering Sea, provenance studies have explored the mineralogy of bulk sediment (Rex and Goldberg 1958;Morley et al 1987;Nechaev et al 1994) and the <2 μm fraction (Griffin et al 1968;Rateev et al 1969;Heath and Pisias 1979;Naidu et al 1982Naidu et al , 1995Naidu and Mowatt 1983;Blank et al 1985;Underwood and Hathon 1989;Hathon and Underwood 1991), radionuclide tracers in bulk sediment (Nakai et al 1993;Asahara 1999;Pettke et al 2000;Asahara et al 2012), the geochemistry of bulk sediment (Gardner et al 1980;Nakai et al 1993;Weber et al 1996;Serno et al 2014) and the <63 μm fraction (Olivarez et al 1991), and sand composition (Gergen and Ingersoll 1986). Grain-size characteristics have been less commonly used to infer terrigenous sediment supply in this region but have proved to be a pivotal tool (Rea and Leinen 1988;Rea and Hovan 1995;Serno et al 2014).…”

Composition of fine‐grained sediment in the Hikurangi Trough: Evidence for intermingling among axial gravity flows, transverse gravity flows and margin‐parallel ocean currents

“…That trend has been attributed to transverse and axial infilling from continental sources in the eastern Gulf of Alaska, changing to transitional sources on the Alaska Peninsula to intra‐oceanic volcanic islands in the central and western Aleutians (Underwood, 1986a,b). Coeval clay mineral assemblages, in comparison, show much less along‐strike spatial variation, with consistently high proportions of detrital illite and chlorite supplied by continental sources to the east (Naidu & Mowatt, 1983; Underwood & Hathon, 1989; Hathon & Underwood, 1991). Surprisingly, smectite is subordinate, even in the central Aleutians.…”