Nature and timing of faulting and synextensional magmatism in the southern Basin and Range, central-eastern Durango, Mexico
Aguirre-Diaz, Gerardo J; McDowell, Fred W (1993) Nature and timing of faulting and synextensional magmatism in the southern Basin and Range, central-eastern Durango, Mexico. Geological Society of America Bulletin, vol.105, no.11, pp.1435-1444, Nov 1993
| Authors | Aguirre-Diaz, Gerardo J; McDowell, Fred W |
|---|---|
| Year | 1993 |
| Title | Nature and timing of faulting and synextensional magmatism in the southern Basin and Range, central-eastern Durango, Mexico |
| Source | Geological Society of America Bulletin, vol.105, no.11, pp.1435-1444, Nov 1993 |
| Publisher | Geological Society of America GSA, Boulder, CO, United States USA |
| ISSN | 0016-7606 |
| GeoRef | 1993-038722 |
| Keywords | alkali basalts; basalts; Basin and Range Province; basin range structure; block structures; Cenozoic; cross sections; Durango Mexico; extension; faults; high-angle faults; igneous rocks; lava flows; magmas; Mexico; Miocene; Nazas Mexico; Neogene; normal faults; North America; sedimentation; structural controls; syntectonic processes; systems; Tertiary; volcanic rocks; volcanism |
| DOI | 10.1130/0016-7606(1993)105<1435:NATOFA>2.3.CO;2 |
Abstract
The Nazas area, in the central-eastern portion of the state of Durango, is within the poorly studied southern half of the Basin and Range province in Mexico. At Nazas, high-angle normal faults that cut part of the mid-Tertiary volcanic sequence strike between N 20 degrees and 70 degrees W, with 40% of them between N 40 degrees and 50 degrees W. Tilting of faulted blocks varies from 5 degrees to 35 degrees to the northeast, most commonly around 25 degrees NE. A few blocks are tilted to the southwest as much as 25 degrees . Fault offsets range from 40 m to nearly 300 m. The earliest faulting occurred between 31 and 29 Ma, before the emplacement of mid-Tertiary ash-flow tuffs had ended. The Santa Ines Formation, a widespread fanglomerate, was deposited after the earliest faulting episode and is overlain by 24 to 20 Ma alkalic basalt flows. Although not cut by faults, the flows are adjacent to or cover normal faults. Some of the mapped faults could have been coeval with basalt eruption, as is the case in Trans-Pecos Texas, where alkalic basalt having similar age and composition to that in the Nazas area erupted contemporaneously with normal faulting. The Nazas alkalic basalt also has similar age and stratigraphic position as, but is compositionally distinct from, the Southern Cordilleran Basaltic Andesite (SCORBA), a widespread mafic suite in southwestern North America that has been linked to regional extension.