Paleomagnetic estimation of emplacement temperature of pyroclastic deposits-preliminary study of caldera de los Humeros and Alchichica crater

Abstract

Preliminary palaeomagnetic results from pyroclilsüc deposits of a large caldera (Los Humeros) and a small explosion crater (Alchichica) are reported. The data are analyzed in terms of a simple classificaüon scheme based on the directional properties of initial remanent magnetization and demagnetized .. remanent magneüzations. The deposit studied in Los Humeros caldera is an ignimbrite with an emplacement temperature of about 4SOQc or higher. Deposits studied in the Alchichica explosion crater were deposited with emplacement temper!ltures between 100°C and 300°C with sorne of the lithic clasts cooling before and sorne cooling during the final deposition.