[69188] ~R.e.a.d@ !O.n.l.i.n.e! Propylitization of Tertiary Volcanic Rocks Near Ebbetts Pass, Alpine County, California (Classic Reprint) - Howard G Wilshire %e.P.u.b@
Related searches:
3801 3389 3066 3832 3380 926 4253 31 1388 4975 4648 3737 3127 4837 950
Geology and geochemistry of tertiary volcanic host rocks, sleeper gold-silver deposit.
This study considers the nature, distribution, and genesis of alteration-mineralization in the igneous rock environment at christmas. At the southeast end of the dripping spring mountains, the pennsylvanian naco limestone is unconformably overlain by the creta.
The northern and central parts of the volcanic center and beyond have been cut by three major, but local, northwest-striking, silver-rich, fissure vein systems accompanied by proximal silicification and widespread pro-pylitization of host rocks and less extensive crosscutting phyllic and argillic alteration facies. Previous investigations have shown that three mineralization stages occurred, with gold to silver ratios which vary from 1/72 to 1/214 in ores that have recently been exploited.
The mid-tertiary latir volcanic field in northern new mexico comprises intermediate-composition volcanics overlain by a regional ash flow sheet and associated lavas of rhyolitic composition that.
Recent exploration in the region of bazman in se-iran led to the discovery of gold mineralization in different prospects. The epithermal gold mineralization at chahnali prospect is hosted by late tertiary andesites and dacites which had been affected by a widespread and intense alteration including propylitization, argillitization, and silicification.
The volcanic activity is far too old (23 my) to act as a source of heat in the area. Metasedimentary, granitic, volcanic, and alluvial clastic rocks may act as geothermal reservoirs. Thick lacustrine clays and alluvial-fluvial sediments as well as thick tuffaceous units have strong thermal insulating or cap rock properties.
To the north and east this old volcanic unit is in normal fault contact with tertiary volcanics which were not investigated for this report. Locally, in the southern half of the area, the late paleozoic to early mesozoic volcanic sequence is intruded by a late mesozoic granite porphyry', which was also included in the thrusting.
The latter’s would be apophyses of volcanic chambers of basaltic shorsholeti suite. The mineralization coincide with high temperature epidote-zoisite propylitization. The high temperature hydrosulfide fluids of propylitization leached au from goldbearing k-feldspar altered rocks and it was the reason the high.
Of the zone of intense propylitization, and of the andesite joints are all closely similar. In addition, the dips of the lode and of the joints are both close to vertical. It thus appears that the rich pyritization and the proplitization were structurally rather than lithologically controlled.
The propylitization was of regional 115 km2, is rather flat, and has an average altitude of 1000 scale and predated the mineralizing events. It is located between the bazman volcano to the south a first-stage gold mineralization occurs along a series of n–s and the samsur plain to the north (fig.
Tertiary meteoric hydrothermal systems have altered the rocks exposed over more than 5 % of the land surface of the northwestern united states and southern british columbia, including at least 25,000 kmsup2/sup in idaho. The systems typically involved convective circulation of fluid derived from ordinary meteoric groundwaters around crystallizing, calc-alkaline, epizonal plutons emplaced.
The mines of the district occupy a window of paleozoic sedimentary rocks in overlying tertiary volcanic rocks. The bulk of the production came from shallow oxidized lead-silver ore bodies that formed along silicified fault zones between the paleozoic sedimentary rocks and overlying tertiary volcanic rock.
The tertiary volcanic rocks in the mineral mountaln area are part of a long and complex hlstory of tertiary volcanism in southwestern utah and southeastern nevada. The volcanlc rocks are mainly ignimbrites; however, some local andesite flows and tuffs are also present.
Decalcification increased porosity, allowing introduction of mineralizing fluids.
Tertiary meteoric hydrothermal systems have altered the rocks exposed over more than 5 % of the land surface of the northwestern united states and southern british columbia, including at least 25,000 km 2 in idaho. The systems typically involved convective circulation of fluid derived from ordinary meteoric groundwaters around crystallizing.
Process of propylitization in the volcanic rocks is connected with an increased content of chlorite, epidot, albite, pyrite and calcite. These are minerals with relatively high density, which, for example, is up to 3,50 g/cm3 for the epidot. Respectively, the propylitization leads to a relative increase of the density.
Ments and volcanic rocks offshore to the west of the continental margin. Early tertiary volcanic eruptions filled the western basins with volcanic de- bris, which.
Called as middle-southern mountain belt in the south and volcanic belt in the northern part. It is stated that cineam area is also belonging to the volcanic belt (ji ca-dmr,1995). At the southern and middle district the rocks mainly composed of oligo-miocene jampang formation volcanic series, while volcanic members of jampang.
The alteration is one of those post-volcanic, pneumatolytic processes, so frequent in volcanic districts. Propylitization consists in the replacement of the original minerals of the andesite by secondary products such as kaolin, epidote, mica, chlorite, quartz and chalcedony, often with the retention of the igneous structures of the rocks.
Argillization, sericitization, and propylitization are the most common types of hydrothermal alteration in the area. The neogene sediments consist mainly of loosely consolidated, unsorted, and poorly stratified conglomerate and sandstone overlying the eocene volcanic-sedimentary rocks.
Is related to the tertiary volcanic rocks, especially the altered basaltic-andesitic breccia, tuff and lava units of the hulusimpang formation (amin et al, 1994). The silica is massive or colloform ba nded, with evidence of various degrees or episodes of hydraulic fracturing and brecciation.
Page a-124 - pre-tertiary stratigraphy and upper triassic paleontology of the union district, shoshone mountains, nevada us geol.
Are mainly late cretaceous granitoids with minor late tertiary and quaternary volcanics, sand-stone and conglomerate. Strong volcanisms in pliocene to pleistocene were recognized and early pleistocene dacite and andicitic terrestrial volcanics distribute in the huanggua-qingoliuhuang-.
However, base metals and gold mineralizations in cihonje area, gumelar, banyumas that have potential as hosted rocks of base metals and gold are in tertiary sedimentary rock. Therefore, the rocks need to be investigated by field research for sampling and then laboratory petrographic.
Tertiary volcanic province of northern east greenland in the gauss halvo-hold with hope region (fig. 1980) where initial intrusions are affected by intense propylitization.
Chlorite is the name used for a group of sheet silicate minerals that are usually green in color, have a foliated appearance and an oily to soapy feel.
Propylitization of tertiary volcanic rocks near ebbetts pass, alpine county, california by wilshire, howard gordon, 1926-publication date 1957 topics.
(three phases of tertiary- quaternary volcanism (1) early tertiary (43-33 ma) flows of island arc tholeiites;(2) tholeiitic pillow basalt at beginning of late miocene (11 ma); (3) pliocene-quaternary medium-k calc-alkaline magmatism.
The surface geology is dominated by tertiary volcanic units in the comstock district, and in areas to the east and north. In general, the basin and range is an area of crustal thinning and high heat flow [stewart, 1978].
Late tertiary granodiorite, diorite, monzonite and tonalite in the volcano-sedimentary complex. A detailed de-scription of the geology between the rafsanjan belt and sirjan belt, in which the study area is located, is given by [96]. The eocene volcano-sedimentary rocks consist of trachybasalt and trachyandesitic tuffs, lava flows and por-.
Juxtaposes pre-tertiary strata against a dominantly eocene and younger volcanic pile. Property geology the cutoff property is underlain in the northeast by upper jurassic hazelton group andesites, dacites and rhyolites, centrally by upper cretaceous kasalka group.
Magmatic evolution and compositional characteristics of tertiary volcanic rocks associated with the venarch manganese mineralization, sw qom, central iran.
Ous results, provide insight into the tertiary magmatic history of the district, and suggest the exact origin of the material that pro- duced the tertiary magmatic rocks. Sasa, toranica, volcanic rocks, age, origin, contamination, tertiary introduction tertiary volcanic rocks in the osogovo-besna kobila (sasa-.
Hydrothermal alteration is pervasive in lava flows but weak and localized near veins in volcaniclastic rocks. Hydrothermal alteration types include silicification (quartz-adularia and quartz-illite) and propylitization (chlorite + calcite ± illite).
Dependently of the wide development of the edium and low temperature hydrothermal al tions of the upper cretaceous and tertiary olcanics in the srednogorie and rhodope zone, their terminological designation and use too various.
Tertiary meteoric hydrothermal systems have altered the rocks exposed over more than 5 % of the land surface of the northwestern united states and southern british colum.
In geology, igneous differentiation, or magmatic differentiation, is an umbrella term for the various processes by which magmas undergo bulk chemical change during the partial melting process, cooling, emplacement, or eruption.
Hydrothermal alterations are silicification, sericitization, argillization and propylitization. 75: tertiary volcanics extruding silurian sediments, mineralization occurs in both rocks and are composed of veins, stockworks and veinlets hosting zn-pb-ag.
Series of tertiary sandstone, slate and intermediate-basic volcanic rocks, and there are a great amount of intermediate-basic subvolcanic facies ultra-hypabyssal intrusion accompanying the eruption of intermediate-basic volcanic rock, the main lithological characters are andesite.
Subject category comment text; deposit: a bonanza strike in the comstock's middle group, this deposit was mined to the bottom of its ore body by 1870.
![[69188] @Download! Propylitization of Tertiary Volcanic Rocks Near Ebbetts Pass, Alpine County, California (Classic Reprint) - Howard G Wilshire @P.D.F@](images/1515745165l_37211622.jpg)
[69188] Post Your Comments: