Search USGS⌕ Search

Geology topics

D. L. Campbell

Publications and source records attributed to D. L. Campbell.

At least 19 recordsLinked to original sources
USGS1986

Aeromagnetic map of the Holy Cross Wilderness Area, Eagle, Lake, and Pitkin counties, Colorado

The Holy Cross Wilderness (02–170), called simply "the wilderness area" in this report, lies in the northern Sawatch Range of Colorado. Regionally, the wilderness area lies on a strong gravity gradient that marks the northwest side of the deepest gravity low in the central United States (Behrendt and Bajwa, 1974). This low (fig. 1) reflects a series of Laramide and younger granitic intrusive bodies which are probably related genetically to the Colorado mineral belt (Tweto and Sims, 1963; Behrendt and others, 1968). The wilderness area lies on a structural dome, on which Proterozoic basement rocks have been uplifted, exhumed, and sculpted by glacial and fluvial erosional processes into spectacular alpine ridges. Steep faults bound the western edge of the dome; west of these domal border faults lies a sequence of Paleozoic sedimentary strata, which dip gently and thicken to the west. The dome is marked by an oval regional gravity high (Webring, written commun., 1985) whose shape suggests that maximum domal uplift may have occurred along or just to the east of the domal border fault complex. For more extensive descriptions of the regional geologic setting and mineral deposits of central Colorado, see Tweto (1968). Map B is a generalized bedrock geologic map of the wilderness area, showing locations of faults, shear zones, and geologic units referred to in this report. Many smaller outcrops are not shown on Map B, however. For precise locations, descriptions of geologic units, and a more complete discussion of the geology of the wilderness area, see the companion map by Wallace and others (1986).

Colorado↗
USGS1985

Gravity and aeromagnetic maps of the Maroon Bells-Snowmass Wilderness and additions, Pitkin and Gunnison counties, Colorado

Aeromagnetic and complete Bouguer gravity anomaly maps have been prepared for the Maroon Bells-Snowmass Wilderness and additions, near Aspen, Colorado. An extreme gravity low, which may be indicative of mineralization, occurs over the White Rock pluton in the southeastern part of the study area. Modeling of the gravity and magnetic anomalies shows that the Sopris, Snowmass, and White Rock plutons are probably all stocks connected to a single batholith at depth. Both Sopris and Snowmass stocks seem to be shaped like spikes bristling out of this common batholith; the Snowmass spike is vertical, the Sopris spike is inclined. The Snowmass spike has a westward-extending flange, possibly related to the Elk Range thrust zone. The White Rock stock is a massive conical lump on top of the underlying batholith. Its complicated aeromagnetic signature seems partly due at least two magnetically distinct regions, which may represent altered zones or separate intrusions within the stock. These regions occur under the Conundrum Creek and East Maroon Creek valleys and may represent favorable locations for mineralization.

Colorado↗