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

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For reasons of simplicity and clarity, the stratigraphic units which were recognized in the La Pimienta Phyllite are designated by letters rather than names. The resulting 20 values are plotted against An content on the graph of Bambauer et al.

Term Bank – potasio – Spanish English Dictionary

Is a homogeneous, mediurn-dark-gray N4slaty phyllite. These dates which indicate the last episode of metamorphism closely correspond with the dates for the diorite Member i, is approximately m thick and is the most widespread member.

Metamorphic Ages Both Mapes Vazquez op. These conclusions are unsupported by our observations. Both minerals are fine grained and occur with sericite. Flores, Teodoro,Etude miniere du district de Zacatecas, Mexico: Adjacent to the contact, Ienses of diorite less than 1 m in length occur concordantly within the phyllite.

Figure 5 is a plot of both the poles to bedding-plane cleavage contoured and the trend and plunge of fold axes for rocks occurring onIy in Arroyo Talamantes.

Plotting of additional structural data may cause the two maxima described in Figures 4 and 5 above to merge into a single maximum. In hand specimen, sample 26 is a homogeneous fine-grained marble.

The anomalous chemistry and altered mineralogy appear to be the result of both hydrothermal and deuteric alteration. The lowermost metamorphic unit, dtacion is exposed in Arroyo del Alamo, is designated Unit A.

The quartzite lacks obvious follation, but exhibits a crystalloblatic texture and is very hard. Relict minerals and textures suggests that some minerals did not react completely during metamorphisrn. Previous investigators of the Sierra de Zacatecas have described the rocks in potzsio area in a general manner, and formational ilames, with one exception, have not becn applied. Age and structural relationships indicate that the intrusion of the Las Pilas Diorite was concurrent with the deformation an metamorphism of the La Pimienta Potasi.


Sample 25 is a diorite that, in spite of some alteration, still retains its original textural and mineralogical features.

Datación Potasio-Argón (K-Ar)

These shallow dips coupled with the fact potasii the Arroyo runs along strike account for the great extent of this unit. Sample 8 is representative of the phyllites that have been subjected to metamorphism of an intensity datacioj enough to have destroyed most relict sedimentary textures and minerals.

Interbedded fine-grained, grayish-purple and grayish-orange phyllite; contains lenses of marble and metaconglomerate. In hand specimen light-gray feldspar phenocrysts are set in a greenish-colored, fine-grained matrix which is cut by thin white veinlets of calcite.

Further study, centered around datcion chemistry of individual mineral phases, is necessary before the detail of these reactions can be successfully learned. It is likely that this unit is intensely folded because of its relative incompetency.

Cserna, Potaasio de,Tectonics of northern Mexico: The mineralogy of the metamorprnc rocks is dominated by quartz and sericite. No definite conclusions can be drawn from the structural data gathered in the La Pimienta Phyllite. This formation is the oldest unit in the fleld area.

Layer: Dataciones (ID: 3)

Abstract Triassic metasediments, a Cretaceous intrusive, and Tertiary intrusive rocks comprise the major rock types west of the city of Zacatecas. Additional plagioclase was separated by heavy liquid from twelve other powdered dibritc samples whose An content had been previously determined on the universal stage in order to determine their structural states.


In thin section the major phases, quartz and sericite, are accompanied by alkali feldspar, plagioclase, iron oxides and hydroxides, and minor biotite. K 2 O is anomalously abundant in three samples, but falls to less than 0. One of these species J uvavites Anatomites mojsvari Burckhardt, is known to be of Late Triassic age and has a definite occurrence in Mexico.

Alteration products are primarily chlorite and fibrous amphiboles. Calcite ranges in grain size from less than 0.

Datación potasio-argón (K-Ar)

The metasediments are intruded by a shallow diorite pluton. Pods and lenses of metaconglomerate, which are characteristic of member iii, occur both conformably and in fault contact with the interbedded phyIlite and quartzite. As there is no evidence for an unconformity within the La Pimienta Phyllite, it is believed that the entire sequence is of late Triassic-Jurassic?

Analyses of 16 samples of igneous and metamorphic rock Arrgon 3 and 4 were performed by X-ray spectrography and atomic absorption spectrometry.

Intrusion of a relatively dry diorite magma into a sequence of sedirnents undergoing greenschist facies metamorphism would probably result in the production of hot aqueous solution in amounts sufficient to have produced the pervasive autometamorphism of diorite. Locally, relict graded bedding is useful in determing the tops of the beds. Fine-grained, relatively homogeneous, dense. Member i Fine-grained, grayish-orange phyllite.

The grayish-purple phyllite typically contains remnant burrows. Chemical analysis of metamorphic rock types. Groundmass quartz ratacion usually interspersed with sericite, and grains show slight elongation, with long axes subparallel to the long axes of sericite flakes.