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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Most fragments are fine grained and of uncertain mineralogy. Acknowledgments The authors are grateful to Dr.

Datación potasio-argón (K-Ar)

The topographic map, which served as a potasil for the general geologic map of the region, has a scale too small 1: Rock samples from Table 6 plotted on the AFM projection plane. At most exposures, however, the marble appears massive and unfolded. This member is also a very fine-grained 0. It occurs in the groundmass with plagioclase and as stubby, subhedral to anhedral microphenocrysts.

Sample 8 is representative of the phyllites that have been subjected to metamorphism of an intensity high enough to have destroyed most relict sedimentary textures and minerals. Abstract Triassic metasediments, a Cretaceous intrusive, and Tertiary intrusive rocks comprise the major rock types west of the city potssio Zacatecas.

The intense folding makes it difficult to determine the units thickness. An datackon map of the major arroyos shows the structural detail at a scale of 1;2, Figure 2. In the case of quartz, porphyroblasts begin to form. This orogeny, which is probably equivalent to a phase of the Nevadan orogeny, appears to correspond well with the argoh period of deformation and metamorpbism determined by our study of the rocks near Zacatecas.


This province consists mainly of a basal sequence of andesitic to basaltic volcanic rocks overlain by dacitic and rhyolitic ignimbrites, tuffs, and lavas.

Term Bank – argon – Spanish English Dictionary

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

X-ray diffraction patterns were run for all the plagioclase. Thus the formational names used in this report are being presented for the first time. Metamorphic Ages Both Mapes Vazquez op.

Chemical data plotted on an AFM diagram is shown in Figure A second c1eavage, consisting of small fractures, disrupt and offset the original cleavage. Minor chlorite 3 percent and epidote 2 percent also are present.

Small grains of quartz 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 abundance of phyllite fragments readily differentiates this metaconglomerate from that found in Unit B. The cleavage consistently strikes approximately north-south and dips to the east at moderate angles. The clase association in time of the metasediments and the diorite intrusion suggests that the temperatures necessary for greenschist facies metamorphism were attained at shallow depths in the crust.


Metamorphic albite is present in most of the phyllites, whereas metamorphic microcline is a rare constituent. This very fine-grained calcite may coarsen to blocky, sparry calcite, and veins ofsecondary sparry calcite are abundant. Regional setting The area of study is part of the Mesa Central morphotectonic province of central Mexico. Marbles containing thin layers of sericitc display foliation, whereas the quartzite is always massive.

Rcliet quartz grains show a variety of extinction types, ranging from undulose to straight, and contain minute inclusions.

Few geologic studies have been made of the Sierra de Zacatecas in spite of the great economic importance of the area. Faulting and erosion taking place at this time led to the deposition of the Zacatecas Conglomerate. The possible second phase of folding and metamorphism detected in the rocks poatsio Zacatecas is probably the result of some later period of Laramide activity. Most of the more competent units above and below are not as extensively deformed. The most abundant metamorphic rocks in the field area are phyllites, some of which have slaty or schistose affinites.

Photomicrograph of hydrothermally deuterically altered diorite sample No.