POR FISIÓN; DATACIÓN POR HELIO; DATACIÓN POR PLOMO ; en el am- biente acuático. datación por potasio-argón Método para determinar la edad. Request PDF on ResearchGate | Cronologia potasio-argón del Complejo Efusivo Copahue-Caviahue, Provincia del Neuquén Potassium-Argon chronology of. d Kalium e potasio potassium-ammonium chloride; potazote () argon d Kalium – Argon Alterbestimmung e datación con potasio – argón

Author: Malagar Zuluhn
Country: Indonesia
Language: English (Spanish)
Genre: Personal Growth
Published (Last): 26 December 2008
Pages: 389
PDF File Size: 7.24 Mb
ePub File Size: 9.97 Mb
ISBN: 797-1-56529-872-4
Downloads: 99286
Price: Free* [*Free Regsitration Required]
Uploader: Zololl

Petrography Satacion description and cIassification of the rock types encountered in the course of geologic mapping are presented along with specific examples of texture and mineralogy of individual rock samples.

AdditionalIy, he feels that the schist-Upper Triassic contact might very well be a folded thrust.

Bioclasts or even recrystallized bioclasts appear to be absent in the foliated and nonfolialed marble. Relict sedimentary plagioclase feldspars An displaying albitc twinning are abundant as are irregularly shaped masses of iron oxides and hydroxides. An contents are quite variable, ranging from An 38 to a low of An 8.

The marble is dominantly composed of very fine-grained 0. Two periods of folding are supported, however, by lenses of marble occurring conformably within the phyllites of Arroyo Talamantes, which show two directions of folding within a single hand specimen. The two-point maxima obtained in this pIot are more distinctly separated than the maxima in Figure 4, and the suggestion of two episodes of folding is stronger.

Plagioclase feldspars are the most abundant mineral in the diorite, accounting for 50 to 70 percent of the rock. Since there are almost no geopetal structures, the beds are assumed to be right side up and the age relations are based purely on stratigraphic position.

The Sierra de Zacatecas has been the site of mineral explotation since the mid’s, yet much remains to be learned about the geologic history of this region.


Datación Potasio-Argón (K-Ar)

Lithic fragments occur in phyllites which have been incompletely recrystallized. The metamorphic and relict mineral assemblages for each potxsio are given in Table 5. The body has a tabular shape and because of its resistance to weathering can be traced for a short distance out of the Arroyo.

In conclusion, the metamorphic mineral assemblages Table 5 are indicative of greenschist facies regional metamorphism.

Eighty to ninety percent of the clasts composing the metaconglomerate are quartzite, with the remaining ten to twenty percent being fragments of phyllite. In hand specimen it is fine grained, foliated, and micaceous.

Datación Radioquímica by Dave Von Hohenheim on Prezi

The absence of mineralized veins in the rhyolite flows, at least in those presentIy dtacion, suggests that these volcanic rocks were emplaced after the ore mineralization. The name diorite is used herein chiefly because of the instrusive nature of the rock and its intermediate composition.

Other phenocrysts were wrapped in platinum foil and heated in a graphite crucible with an oxygen-acetylene torch, producing a plagioclase glass. These feeder dikes are particularly well exposed along the new highway which borders the city of Zacatecas on the west and the north for a detailed geologic section see Barr, op.

Datación potasio-argón (K-Ar)

Within the phyIlite are conformable lenticular bodies of metaconglomerate, quartzite, and marble. Petrochemistry and petrogenesis Analyses of 16 samples of igneous and metamorphic rock Tables 3 and 4 were performed by X-ray spectrography and atomic absorption spectrometry. Sericitization typically obscures fragment borders and makes primary mineralogy unrecognizable. No radiometric dates exist for the siliceous schist fine-grained slaty phyllite of this reportbut personal communication with J.

McGehee in his study of the La Pimienta metamorphics has also failed to find evidence of a major unconformity.

Quartz and sericite are present in about equal proportions and constitute 90 percent of the rock with accesory epidote 1 percentalkali feldspar 5 to 7 percentand opaque minerals 2 to 4 percent. The lowermost metamorphic unit, which is exposed in Arroyo del Alamo, is designated Arton A.


Arhon, diorite is altered to the extent that primary texture and mineralogy arc obscured. Since the wide range of these bivalves makes them undesirable for correlation, the validity of this age is questionable from a paleontological standpoint. Sericite is ubiquitous in all samples plotted on the ternary diagrams, and pyrophyllite may actually be present but not recognized due to the difficulty in distinguishing datacoin from sericite optically. In addition, exposures of this metaconglomerate are smaller and more prevalent.

Khan Academy on a Stick : Datación Potasio-Argón (K-Ar)

Photomicrograph of hydrothermally deuterically altered diorite sample No. These three lines of evidence 1 stereographic plots; 2 two directions of folding in carbonate lenses; and 3 petrofabric evidence, combine to produce a good, but not a conclusive case in favor of two episodes of deformation.

Homogeneous, fine-grained, medium-dark-gray, slaty phyllite; contains metaquartzite tenses.

Since the ptasio are much more extensive south of this area and are the focus of another study Brown, op. An alternative explanation for the absence of chloritoid may be that a qrgon assemblage is present. The Las Pilas Diorite has the charachteristics of a hypabyssal intrusion. Although we favor an intrusive origin for the entire diorite sequence, an extrusive origin for part of the diorite cannot be excluded.

Large quartz grains 0. A possible explanation for the observed change in style of folding is difference in the competency of the stratigraphic units which predominate in the two arroyos. Stable mineral assemblages in Figure 9a include: