Papachacra, Belén Department, Catamarca, Argentina
|Latitude & Longitude (WGS84):||27° 0' 59'' South , 66° 52' 0'' West|
|Latitude & Longitude (decimal):||-27.01639,-66.86667|
|Köppen climate type:||Cwb : Subtropical highland climate or temperate oceanic climate with dry winters|
Granite stock of the Papachacra formation, geological structure in which there are deposits and mines, is located 75 kilometers in a straight line to the North of the town of "Belén" in the province of Catamarca, Argentina. It is accessed to this place, from "Belén", through national route No. 40 until the town of "El Eje" (47 Km), to continue from there by national route 53 until "Puerta de Corral Quemado" (19 Km) and then by the provincial route N ° 36, 17 Km to "Corral Quemado". Throughout this journey is gravel and well preserved. The 20 Km remaining to the village of Papachacra, to the North, are irregular, and should be done in 4 x 4 vehicles.
Granite stock of the Papachacra formation, on its western slope ("Cerro León Muerto"), has a slightly oval shape, with the shaft more willing southern, and its approximate boundaries are: the river "La Cuesta" to the North, the "Quebrada del río Blanco"(El Cajon) to the South, the town of "Papachacra" East and spot "Pampa del Arrimo" by West. Located within the system of "Sierras Pampeanas" has an approximate height of 3,100 m. asl. It is embedded within the orthogneiss of the "Chango Real Formation" and it is a whitish-pink granodiorite of texture granular media in pseudo porphyrics and aplitics sectors. It is composed of quartz, plagioclase, orthoclase, biotite, Muscovite, tourmaline, Topaz, fluorite and opaque. This stock was subjected to a process of deuteric alteration , because streams rich in volatile, formation of miaroles filled with crystals of potassium feldspar (Microcline) idiomorphics, smoky quartz, Muscovite, Topaz, florencite (Ce), tourmaline, etc. These processes of alteration are also evident in aftermath of albitization and silicified, which are joined by a marked Kaolinization of minerals of the first generation and cataclastics phenomena. According to its modal composition one can classify this rock as a monzogranite on the border between sub alkaline and alkaline Granites. Conducted isotopic dating, K/Ar, shed an age of 117 million years (± 20 million years), corresponding to the lower Cretaceous.
Intruding "El Portezuelo" (granite Papachacra) granite is a courtship of trend alkaline rocks. The late intrusive in this group are rhyolites per alkaline (comendites) with extremely high content of some HFSE (Zr, Nb, Y, etc.). They are classified as granitoid of type A, and inside them belong to the Group A1. This suggests an extensional rift or environment of hot point towards the upper carboniferous, considering that the shutdown Rb–Sr trend alkaline rocks occurred around 300 Ma. The relationships of elements trace are allied with differentiated mantle melt contaminated in a variable degree with cortical material. Rb–Sr isotopic data also point to a volcanic source or lower crust.
Genetic phenomena and subsequent hydrothermal alterations, which resulted in crystallization and recrystallization, gave to the formation of an exceptional richness, not only in mineralogical variety, but also in the form developed by the crystals, which adds the valuable jewellery quality of some species. The Topaz of this region offer a degree of transparency and purity, that coupled with the variety of colors (yellow, Orange, Brown, blue, colorless) make possible the carved stones of great value. The same happens with the varieties of quartz, among which the smoked, the citrine and Amethyst are in order of importance. Fluorite, another species of gemological interest, comes in purple, green and pink colors with full transparency. The rest of the minerals, which is not of gemological interest, present perfect crystalline forms and exceptional sizes, to which are added combining them in one piece, which gives you an invaluable for collections and Museum, as well as ornamental.
The associations most common smoky quartz is idiomorphic crystals of: Microcline in shades of pink to Brown, clear, Albite (var. Clevelandite), Muscovite, black tourmaline (var. Schorl) and hyaline Quartz.
In the granite of Papachacra this Association an amount of up to rare and less abundant minerals making are incorporated into interesting crystalline aggregates for museums and collections. Associated with most idiomorphic crystals of:
Fluorite, among others.
Smoky quartz and hyaline quartz or rock crystal associated with feldspar is often albite and microcline idiomorphic often occur in pegmatites of the Papachacra granite in the locations described for Topaz. Smoky quartz color varies from brownish to golden brown, idiomorphic crystals of good quality comes to grind.
Mineral ListMineral list contains entries from the region specified including sub-localities
37 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
|Paleozoic - Neoproterozoic|
252.17 - 1000 Ma
|Precambrian-Phanerozoic intrusive rocks|
Lithology: Intrusive igneous rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529.