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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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Quartzite pebbles are rounded to well rounded, and phyllite fragments, which exhibit foliation, are rounded. These two belts, the Jaliscoan on the west and the Huastecan on the east, were sites of Paleozoic geosynclinal sedimentation.

DATACION POR COLAGENO by Aurekee Gmz Solano on Prezi

AIl argno samples plot near the plagioclase low curve, indicating that the plagioclase is ordered, probably as a result of slow cooling. Reconnaissance work to the south of Zacatecas shows that these flows are also present in this direction.

The region of study, approximately 5 km wide and 7 km long, is located in the southern portion of the Zacatecas Quadrangle, Iocated in the State of Zacatecas. The close association in time of the metamorphism and the intrusion suggests that the temperatures necessary for greenschist facies metamorphism were attained at shallow depths in the crust.

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.

The most extensive exposures of the oldest rock types, the La Pimienta Phyllite occur west of the city of Zacatecas indicating that erosion has exposed the deepest levels in this vicinity. The structural orientations of the stratigraphic units described above are shown in Figure 2.

The predominant minerals are quartz and sericite, but minor amounts of alkali feldspar, plagiocIase feldspar, epidote, chlorite, biotite, and iron oxides are present. Dengo therefore, proposes that this tectonic element be considered a separate tectonic belt. Locally the marble is intensely folded and foliated Figure 3.


Olivine is rare in the diorites, and its positive identification was made only in a few thin sections. Diorite dikes cutting through the quartzite are prevalent. Both minerals have a prismatic habit and, because of their very small size average 0.

Rocks of Units C and F contain a fracture cleavage consisting of microscopic fractures which disrupt and offset the primary cleavage. 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. All metamorphic rocks exposed in the area of study are of the greenschist facies of regional metamorphism.

Phyroxene is the most abundant primary mafic phase and generally accounts for 15 to 25 percent of the fiorite. The metaconglomerate lenses range in size from slightly less than 1 m to as much as 10m across. Quartz and albite also may be present in the above assemblages. Magmatism continued into the Late Tertiary with the extrusion of ptasio flows, tuffs, and volcanic breccias.

Datación potasio-argón (K-Ar)

Regional setting The area of study is part of the Mesa Central morphotectonic province of central Mexico. The intense folding makes it difficult to determine the units thickness. Sericitization typically obscures fragment borders and makes primary mineralogy unrecognizable. Relict sedimentary textures generally are not present in either the marble or the quartzite.

The few structural orientations obtained for xrgon cleavage are in accord with the general structural trend of the surrounding units.

Both the Huastecan and the Jaliscoan structural belts were metamorphosed and underwent anatexis during middle Paleozoic time. Thicknesses were estimated with a five foot Jacob staff. Fine-grained, pale-purple to grayish-green schistose phyllite. A report by Mapes Vasquez relics heavily on this early work and is concerned principally with the ore mineralization.


The 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. From these stereographic pIot it cannot be concluded defnitely that two episodes of deformation took place. In as much as this unit is only 8 m thick, it does not provide much structural data. Plotting of additional structural data may cause the two maxima described in Figures 4 and 5 above to merge into a single maximum.

IntenseIy-folded, fine-grained, medium bluish-gray phyIlite.

Pods and lenses of metaconglomerate, which are characteristic of member iii, occur aron conformably and in fault contact with the interbedded phyIlite and quartzite. In general, this quartzite is nearly identical to the lenticular bodies of quartzite which occur in overlying units. Minor chlorite 3 percent and epidote 2 percent also are present.

The relatively high water content, is as would be expected based on the abundance of the chlorite and actionolite. Photomicrograph of hydrothermally deuterically altered diorite sample No.

Term Bank – argon – Spanish English Dictionary

At present it appears that the rocks underwent two deformationaI events and that differences in structural complexity are probably due to differences poasio the competency of the rock.

Since the rhyolites are much more extensive south of this area and are the focus of another study Brown, op. The contortion and weathering make accurate structural dahacion difficult lo obtain, but generally the foliation strikes north-south with moderately steep dips to the east and to the west.

The Triassic age for the siliceous schist is based on ammonite fragments which, according to Burckhardt op.