PRE-FOUNTAIN AND RECENT WEATHERING ON FLAGSTAFF MOUNTAIN NEAR BOULDER, COLORADO

摘要

Decomposition of granodiorite underlying basal Fountain (Pennsylvanian) formation on Flagstaff Mountain near Boulder, Colorado, was the result of pre-Fountain, probably post-Madison weathering. Chemical and mineralogical studies indicate that the weathering took place in a humid, warm or hot climate and that laterization was the dominant process. The results of pre-Fountain and recent weathering are compared and contrasted. The red color of the Fountain formation is regarded as inherited from a deeply weathered extensive red-stained pre-Fountain regolith.