Characteristics of magnetic carriers responsible for Late Paleozoic remagnetization in carbonate strata of the mid-continent, U.S.A.

Abstract

Magnetic analysis of carbonate strata of the mid-continent region of the United States indicates that the Late Paleozoic remagnetization already recognized in the Appalachians also affects almost the entire mid-continent. Magnetic intensity is regionally variable, with more intense magnetizations occurring on intracratonic arches. Magnetization is carried predominately by magnetite, which often occurs in tiny hollow spheroids composed of well formed octahedral microcrysts. Spheroid chemistry and morphology suggests that the magnetite is authigenic, composed of iron extracted from pre-existing pyrite or clay. The timing of the remagnetization, the character of the magnetite, and the regional variation in magnetic intensity support the idea that the remagnetization is a diagenetic consequence of tectonically-driven brine migration