Chemistry and Mineralogy of Precambrian Paleosols in Northern Michigan

Paleosol profiles can be recognized on a basement terrain of granodiorite, peridotite, and diabase that underlie the upper Keweenawan (?) Jacobsville sandstone. The main characteristics of the granodiorite and peridotite profiles are a substantial loss in SiO₂, Al₂O₃, and alkaline earths; a smaller loss in Fe₂O₃ and NiO; the concentration of dolomite and quartz in paleocaliche horizons; and the strong pigmentation of some of the primary minerals at the lower fringe of weathering. The granodiorite paleosol consists of a mixture of secondary and primary minerals: sericite, chlorite, vermiculite, biotite, muscovite, K-feldspar, dolomite, quartz, hematite, and rutile. The paleosol on peridotite contains chlorite, vermiculite, dolomite, quartz, hematite, and talc. The paleosol profiles resemble present-day ones developed under semi-arid to arid conditions.