Saved in:
| Main Author: | |
|---|---|
| Format: | Artículo científico |
| Language: | en |
| Published: |
Universidad Nacional Autónoma de México
2000
|
| Subjects: | |
| Online Access: | https://www.redalyc.org/articulo.oa?id=56839304 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Table of Contents:
- Magnetostratigraphy of the volcanic sequence of Río Grande de Santiago-Sierra de la Primavera region, Jalisco, western Mexico A. Goguitchaichvili L. M. Alva Valdivia J. Rosas Elguera O. Campos Enríquez A. M. Soler Arechalde C. Caballero Miranda S. Venegas Salgado S. Sánchez Reyes Ciencias de la Tierra Trans Neogene volcanic rocks western Mexico Magnetostratigraphy New paleomagnetic results for 13 sites in volcanic units from Huaxtla, Paso de Guadalupe and Lazo sections in the RíoGrande de Santiago (RGS) canyon and for 5 sites in the silicic center of Sierra de la Primavera (SP) are used to document apreliminary magnetostratigraphy for the Trans-Mexican Volcanic Belt (TMVB) volcanic sequence. The magnetostratigraphicresults are correlated with data for 7 nearby sites in the RGS and 6 sites in the SP, and with available KAr dates. A geothermalexploratory well drilled by the Federal Comission of Electricity in the SP allowed recovery of samples down to a depth of 1361 m,and 8 core samples were studied for paleomagnetism distributed between depths of 93 m to 1358-1361 m. Normal (N), intermediate(I) and reverse ( R) polarities are documented in the volcanic sequence of RGS at Huaxtla, Paso de Guadalupe and Lazosections, as well as in the domes and lava sequences of the SP. The three sections studied in the RGS are around 800 m thick, andinclude a basal rhyolitic ignimbrite (R), the San Cristóbal basalts (mainly R), rhyolites and ash flows of the Guadalajara group(mainly R), the San Gaspar ignimbrite (N), basaltic flows and a rhyolitic dome (N). The SP sequence rests on an andesiticsequence and includes a rhyolite, the San Cristóbal basalts (R), rhyolites and an andesitic flow of the Guadalajara group (R), ashflow tuffs, pre-caldera rhyolites, the Tala tuff (R, I), and intra-caldera lacustrine deposits. The San Cristóbal basalts represent theoldest TMVB units, with dates between 11 and 8 Ma. This interval corresponds to a normal polarity chron that contrasts with thedominant reverse polarity observed in RGS and SP. The normal polarity San Gaspar ignimbrite has been dated at 4.74.8 Ma, andprovides a marker horizon in the Guadalajara region. This ignimbrite and the units of the Guadalajara group (with dates of 5.25.5Ma) are assigned to the Gilbert R chron, with the San Gaspar ignimbrite possibly corresponding to the Thevera N subchron (4.594.79 Ma). The silicic sequence of SP represents the young activity in the region and is assigned to the Brunhes chron. 2000 artículo científico 0016-7169 https://www.redalyc.org/articulo.oa?id=56839304 en http://www.redalyc.org/revista.oa?id=568 Geofísica Internacional application/pdf Universidad Nacional Autónoma de México Geofísica Internacional (México) Num.3 Vol.39