Classification and Geochemical Characterization of Igneous Rocks: Southern Part of Chihuahua City, Mexico
Abstract
Chihuahua City is the capital of the state with the same name, located in northern Mexico. The city was established near the Chuviscar River, but in the last decades it has been extended to the nearby areas (mountains), with volcanic (rhyolitic tuffs), and sedimentary rocks (limestone). The study area includes areas in the south part of Chihuahua City, where we can still find unbuilt lands and it is possible to appreciate outcrops of igneous rocks. This project includes 5 study spots, which are located about 9 km. far from the south extreme of the city. This research is developed in order to complement the geological information in this area, as there is no is detailed record of it. In the geological map H13-10 (SGM, 1997), it is said that the urban area is covered by Quaternary conglomerates, while exploring the region we have located several igneous rocks outcrops. In three of the sampling points, dark colored intrusive igneous rocks with large crystals appear in blocks without noticeable fractures. While in the other two sampling points, highly fractured blocks of pink aphanitic igneous rocks, showing traces of pyrolusite were observed. The petrographic study shows the two different textures that classify these rocks as extrusive (aphanitic) or intrusive (phaneritic), both with quartz and feldspars being the dominant minerals. Geochemical analyses confirm the felsic composition of the rocks, varying form trachytes to rhyolites. The trace element results show high contents of Sr, Ba, V, Rb, and Zr in trachytic compositions, while there are high concentrations of Mn, W, Rb and Co for rhyolitic compositions.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2013
- Bibcode:
- 2013AGUSM.V53A..06F
- Keywords:
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- 1099 GEOCHEMISTRY / General or miscellaneous