Stratigraphic relationships of Cretaceous and early Tertiary rocks of a part of northwestern San Juan basin

Abstract

Tertiary or Quaternary orogenic activities modified the structure of the southeastern part of the 3an Juan Basin causing thrusting along the west border of the Nacimiento uplift and normal faulting farther to the south.

Stratigraphy and regional tectonic implications of part of Upper Cretaceous and Tertiary rocks, east-central San Juan Basin, New Mexico

“…Most of the movement on the Nacimiento fault occurred during the final stages of depression of the basin and elevation of the uplift, after the deposition of the San Jose Formation. A similar timing of def ormational events is recorded in the latest Cretaceous and Tertiary rocks on the northeast-trending Hogback monocline in Colorado (Baltz, 1953). A major problem, then, is that of determining how the different structural trends (which might be the products of differently oriented forces) could have formed contemporaneously, or at least during overlapping periods of time.…”

“…* In the northern third of the Central basin in New Mexico and Colorado, an unnamed member that is mainly shale is stratigraphically equivalent to the lower part of the Llaves Member and to the Regina Member. This northern unit has not been studied in detail, but it seems to persist across the northern part of the Central basin, where it is underlain at most places by sandstone that is equivalent to the Cuba Mesa Member. Rocks probably, or nearly, equivalent to the persistent medial sandstone of the Llaves Member lie on the northern shale unit at many places in the northern part of the basin. The sandstone capping Carracas Mesa east of the San Juan River near the Colorado boundary, and the highest sandstones capping tne Mesa Mountains and H-D Hills southeast and east of Durango, Colo., may also be equivalent to the medial sandstone of the Llaves Member, as may be a persistent sandstone occurring near the top of Bridge Timber Mountain southwest of Durango. This sandstone and the overlying rocks, predominantly red shale, overlap Cretaceous rocks on the Hogback monocline (Baltz, 1953;Barnes and others, 1954;Baltz and others, 1966, fig. 5).…”

“…The Brazos uplift was probably part of a geanticline ( fig. 7) that included the Sangre de Cristo uplift prior to the formation of the Rio Grande trough in Miocene time (Baltz, 1965(Baltz, , p. 2065(Baltz, -2066(Baltz, , 2072). The Sangre de Cristo uplift shed detritus into the Raton basin east of the uplift in Paleocene time (Johnson and Wood, 1956); probably, therefore, the geanticline was the northeast boundary of the Animas and Nacimiento depositional basin.…”

“…The source areas for most of the Cuba Mesa Member were probably the same as those for part of the Nacimiento Formation, that is, the Laramide geanticline ( fig. 7) that included the Brazos and Sangre de Cristo uplifts (Baltz, 1965(Baltz, , p. 2065(Baltz, -2066(Baltz, , 2072, and perhaps part of the San Juan dome. The numerous quartzite pebbles and cobbles in the northeastern part of the area could have been derived from the extensive Precambrian quartzite terranes of the Brazos uplift described by Just (1937).…”

Geology and oil and gas assessment of the Mancos-Menefee Composite Total Petroleum System: Chapter 4 in <i>Total petroleum systems and geologic assessment of undiscovered oil and gas resources in the San Juan Basin Province, exclusive of Paleozoic rocks, New Mexico and Colorado</i>

“…The Animas can be divided into a lower conglomeratic and an upper sandstone and shale sequence (Baltz, 1953). The lower part is composed mainly of andesitic debris derived from source areas to the north of the basin and also contains metamorphic and igneous rock fragments.…”