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The Holbrook Lineaments: The geophysical boundary zone between the Proterozoic Mazatzal and Yavapai Provinces, southwest USA

July 21, 2018

A horizontal gradient analysis of the isostatic gravity and aeromagnetic anomaly grids of the NewMexico-Arizona-southernCalifornia area was carried out, focused on eastern Arizona and western New Mexico, to define the transitional boundary between the Proterozoic Yavapai province to the west and the Mazatzal province to the east. The two provinces differ substantially in their favorability to host Laramide porphyry copper deposits. The gravity field anomaly displays the most continuous lineaments delineating the transitional boundaries between the two provinces. The magnetic anomaly data confirm the boundaries but are less continuous. Inferred left lateral offset and termination of the boundary zone in the southern Basin and Range suggest that the Jurassic Mojave-Sonora megashear may extend over much of the southern Basin and Range in southeast Arizona.