Gravity modeling of the Valles Caldera
D. A. G. Nowell
Published gravity data have been used to reinterpret the structure of the Valles caldera in the Jemez Mountains of New Mexico. Three 2 ½ D gravity profiles were modelled across the Valles caldera and show a combination of uneven collapse and trapdoor subsidence of up to 3600 m deep, hinged on the west with a volume of 750 km3 and some faulted basement blocks. A geological interpretation of one of the profiles suggests that the Toledo embayment to the northeast of the Valles caldera was the site of an earlier "Rubio volcano" (4 Ma to 1.78 Ma). This volcano may have erupted the San Diego ignimbrites (1.78 Ma) to the southwest of the caldera and formed the center of a depression that grew southwestward and then collapsed to form first the Toledo caldera (1.61 Ma) and then the Valles caldera (1.22 Ma).
- Nowell, D. A. G., 1996, Gravity modeling of the Valles Caldera, in: The Jemez Mountains Region, Goff, Fraser; Kues, Barry S.; Rogers, Margaret Ann; McFadden, Les D.; Gardner, Jamie N., New Mexico Geological Society, Guidebook, 47th Field Conference, pp. 121-128.