Accretionary lapilli: what’s holding them together?

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Abstract

Accretionary lapilli from Tagus cone, Isla Isabela, Galápagos were analyzed using scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) techniques. Our main findings are (1) the lapilli formed and hardened in a few minutes while still aloft in the dispersing eruption column. (2) Palagonite rinds developed first on the basaltic glass clasts, and subsequently crystallized (3) The crystallization products contain submicron lamellar crystals of a clay (probably smectite) on the surfaces of basaltic glass clasts and (4) The interlocking of these lamellar clays from adjacent clasts binds and cements them together to form the accretionary lapillus. We argue that palagonite and possibly clay formation occur primarily in the presence of hot water vapor.

Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Accretionary lapilli: what’s holding them together?
Year Published 2016
Language English
Publisher California State University Desert Studies Center
Contributing office(s) Geology, Minerals, Energy, and Geophysics Science Center
Description 10 p.
Larger Work Type Conference Paper
Larger Work Subtype Conference Paper
Larger Work Title Going LOCO: Investigations along the Lower Colorado River: 2016 Desert Symposium Field Guide and Proceedings
First page 256
Last page 265
Conference Date April 2016
Online Only (Y/N) N
Additional Online Files (Y/N) N