Retaining wall construction retaining wall excel spreadsheet. Propyfitic alteration this is a complex alteration generally characterized by chlorite, epidote, albite and carbonate calcite, dolomite or ankerite. Alteration is uniformly strong, and biotite and plagioclase have been transformed into cl ay mineral s. Examples are the rock along the neck of a volcano, on the edge of a pluton that is being emplaced, along a fault plane, enclosing a mineral deposit, or where a vein or dike is being emplaced in volcanoes, wall rock can often become broken off the wall and incorporated into the erupted volcanic rock as. Relationships of intrusion, wallrock alteration and. Geochemical changes during hydrothermal alteration of basement in the stockwork beneath the active tag hydrothermal mound 1 susan e. A retaining wall refers to a structure that is designed and built up to defend the lateral pressure of soil, when any alteration occurs in ground elevation that surpasses the angle of repose of the soil. Pdf onzonkanbani gold deposits located in thabeikkyin township, mandalay region, central myanmar. Wall rock alteration in different rocks follows a similar pattern, with the most important mineralogical changes being sulphidation, replacement of chlorite by muscovite, hydrolysis of feldspar. Thus, studying the processes involved in the interaction of the hydrothermal fluids with the host rock. The hazel coppersilver mine, culberson county, texas, by p. Resources and environment, aist, tsukuba, ibaraki, japan.
The nature, extent, and intensity of wallrock alteration and the extent of widespread stockwork or disseminated type mineralization in the altered wall rocks at. Each entry records the lithostratigraphic unit and identifiers for the core, section, piece, interval, the length of each piece, and the curated depth below seafloor of the top of each piece. This zone represents the proximal wall rock effect of a major. In a major hydroelectric project in dry quartzitic phyllite, the rock mass quality q is in the range of 6 to 10. Near the veins, the wall rock is silicified, sericitized or pyritized, depend ing on the nature of the adjacent vein, and original rock textures are destroyed. In terms of the petrography data, four alteration zones can be recognized from the orevein outwards. These changes in the least to mostaltered wall rock are thought to reflect the variations in intensity of the alteration process caused by differences in temperature, chemical potential, time, or some other factors. Pdf wallrock alteration and metamorphism of a volcanogenic. Department of transportation federal highway administration. Precious gem and semiprecious neargem are relative terms that distinguish more valuable stones from less valuable stones relative to prevailing markets a brief examination of the wyoming state geologic map gives. Wallrock alteration alteration zones are always present, and are generally better developed in metavolcanic rocks than in slates. Significant mineralization is also present in apatite rocks. Hydrothermal alteration usgs publications repository.
Nature of uranium mineralization and associated wall rock. Wallrock alteration article about wallrock alteration by. Designers for the project chose the redirock positive connection pc system to create the harbor wall that stands 23. Produced locally by redirock manufacturer cpm group, the redirock pc walls. The qatruyeh iron deposits, located on the eastern border of the nwse trending sanandajsirjan metamorphic zone, southwest of iran, are hosted by a late proterozoic to early paleozoic sequence dominated by metamorphosed carbonate rocks. Propylitic, sodic, sodiccalcic characteristics albite alteration is generally distributed along fracture and vein envelopes, typically becoming more pervasive toward the centre of the zone of. However, these processes assist in mineral alteration. Hydrothermal alteration can be isochemical, like metamorphism, and dominated by mineralogical changes, or it can. Along the vein, cryptocrystalline quartz is introduced along shears. University of cape town,faculty of science,department of geological sciences, 1998 cited yyyy month dd. Wallrock alteration categories and their geochemical signatures in. To purchase this publication as a pdf download, please order ri0016d. Joint alteration number an overview sciencedirect topics. In addition, essentially all of the ca, na, and sr were lost from the rock during alteration of plagioclase.
Wallrock alteration article about wallrock alteration. The qsystem for rock mass classification, developed at the norwegian geotechnical institute ngi in 1974, originally included a little more than 200 tunnel case histories, mainly from scandinavia barton et al. The wall rock alterations have often been used as a guide to orefinding for where weathering has removed the top of the orebody, these alteration haloes serve as indicator of hidden orebodies. Wallrock alteration of biotite hornfels at the tyrnyauz. Breccia, hydrothermal alteration and structural geology of. Pdf wallrock alteration as a guide to goldbearing fracture zones. Scribd is the worlds largest social reading and publishing site. The term propylitic alteration was first used by becker in 1882 for the alteration of diorite and andesite beside the comstock lode, nevada a.
Examples are the rock along the neck of a volcano, on the edge of a pluton that is being emplaced, along a fault plane, enclosing a mineral deposit, or where a vein or dike is being emplaced. Wallrock hypogene hydrothermal alterations include pervasive silicification. The ore zones occur near an unconformity with overlying middle proterozoic sandstone and breccia conglomerate. It occurs as infill grains or lenses alteration envelopes of the mainstage p1riterich copper and zinc veins. Some of us rockheads actually look at the rocks as we climb them. The intermediate wallrock alteration zone 3050 mt wide is easily distinguished because the sericitization is less intense than in the nearest wallrock alteration.
Barnes hl ed geochemistry of hydrothermal ore deposits, 1st edn. The magnetite ores occurred as layered to massive bodies, with lesser amounts of disseminated magnetite and hematitebearing veins. Propyfitic alteration this is a complex alteration generally. Rock and mineral identification for engineers november 1991 r u. Pyrite is the most widespread and predominant sulfide in stage 6 fig. Hematite occurs as disseminated patches in stage 3 wall. Redi rock wall this program is used for designing advanced retaining walls using redi rock retaining wall systems usa. Kfeldspar alteration is mainly in the upper part of this zone, pervasively distributed in the amphibole trachyandesite, making the wall rock purplered fig. Propylitic, sodic, sodiccalcic characteristics albite alteration is generally distributed along fracture and vein envelopes, typically becoming more pervasive toward the centre of the zone of alteration, where it may form a dense massive rock. The trace metals cu, ni, and zn were leached from the rock, with almost all of the cu being removed. The results of the analysis with critical failure surfaces through the rock mass show that the wall is stable and estimates the factor of safety to be 2.
Certain trends in alteration are commonly observed near archean mesothermal gold deposits. Measure the total length of all the individual rock pieces greater than 4 in. Biotite and plagioclase are readily transformed into clay minerals. Hydrothermal processes and wall rock alteration springerlink. Honnorez4 abstract major, trace, and rare earth element ree analyses of 57 samples of altered and relatively fresh basalts from four different. This wall rock alteration represents the initial stages of an earthquaketriggered metamorphic transformation process that ultimately led to reworking of the lower crust on a regional scale. The wall rock altered by kfeldspar show that finegrained kfeldspar in the groundmass of the amphibole trachyandesite typically have a secondary overgrowth texture fig. Occasionally rock alteration leads to misidentification of lithology as in studies of the amulet rhyolite in the noranda. Chapter k geoenviromental model for lowsulfide goldquartz. The baoban gold field, located in the area of hainan island. To obtain rqd, select all the rock pieces longer than 4 in.
Pdf wallrock alteration in the zwartkoppie shoot, sheba. Widths of alteration zones vary with lithology, size of the vein system, and abundance of minor faults. A new zonation type of wmobearing altered biotite hornfels at the tyrnyauz deposit is reported. Just a little insider stuff from metamorphic petrology. The hazel coppersilver mine, culberson county, texas. Typically, this includes a mottled pink and white granitegneiss with associated secondary clinozoisite, pink zoisite, epidote, chlorite, and white plagioclase pervasively altered to mica. Wall rock alteration alteration zones are always present, and are generally better developed in metavolcanic rocks than in slates. Wallrock alteration in the cochin mining district, new. The zonal sequence from fresh through bleached, softened rock to silicified rock adj acent to the vein is common, but the widths of the altered rock sheath and of individual zones in the.
Wall rock alteration accompanies nephrite development, bleaching adjacent granitegneiss and resulting in a characteristic appearance. It allows analysis of gravity walls with redirock blocks, as well as calculation of mse walls with redirock positive connection pc blocks and mirafi geogrids. Geochemical kinetic simulation on wall rock alteration. Wallrock alteration in different rocks follows a similar pattern, with the most important mineralogical. Alteration can extend away from deposits for many kilometers along shear zones and fault zones. Wallrock alteration alteration of wall rocks produces gradual and generally simple and regular changes in rock lithology, mineralogy, and chemistry. Excerpted from the introduction the hazel mine is one of the oldest mines in texas and has been the largest copperproducing property in the state. Retaining wall is formed with masonry and reinforced concrete. Fluid characteristics of vein and altered wall rock in. The intermediate wall rock alteration zone 3050 mt wide is easily distinguished because the sericitization is less intense than in the nearest wall rock alteration.
The nature, extent, and intensity of wall rock alteration and the extent of widespread stockwork or disseminated type mineralization in the altered wall rocks at these ace properties is not known and may be critical. This study was designed to monitor the changes in composition of fluid inclusions using solid probe mass spectrometry by. Tuwaishan, baoban, and erjia, which belong to the wall rock alteration type. Mineral alteration is distinctly different than the rock alteration process metamorphism. The alteration minerals mainly occur in the wall rock or near the contact zone between the wall rock and quartzcarbonate veins, with chloritecarbonatefuchsite being the principal assemblage. The main features of zonation are similar to those in acid leaching columns. Fractures and faults riddle the earths crust on all scales, and the deformation associated with them is presumed to have had significant effects on its.
Batu hijau is an island arc porphyry coppergold deposit located in the southwest corner of sumbawa island in the sundabanda archipelago of indonesia. Southwest sumbawa island is underlain by early tertiary, lowk calcalkaline to weakly alkaline volcanic and intrusive rocks. Hydrothermal alteration is defined as any alteration of rocks or minerals by the reaction of hydrothermal fluid with preexisting solid phases. In 1993 the system was updated to include more than cases grimstad and barton, 1993. Prospecting and exploration that is a search for precious metals deposits is not a simple process because big deposits were discovered a long time ago. Fragmentation of wall rock garnets during deep crustal. Some minerals are members of a solid solution series and are samples of a range of compositional changes in a continuum, and thus are not mineral alteration products. Wall rock is the rock that constitutes the wall of an area undergoing geologic activity. Types of wallrock alteration associated with the askot. The zones of alteration have a bearing on where one might drill for ore bodies. How was the redirock wall able to stand up to such a harsh storm.
Gold mineralization is associated with wallrock alteration zones with. Tuwaishan, baoban, and erjia, which belong to the wallrock alteration type. Geochemical fingerprinting of carbonate wall rock alteration. It allows analysis of gravity walls with redi rock blocks, as well as calculation of mse walls with redi rock positive connection pc blocks and mirafi geogrids. Minor sericite, pyrite and magnetite may be present, less commonly zeolites and montmorillonites.
Geochemical kinetic simulation on wall rock alteration zoning. Gemstone is a broad term encompassing any mineral that is attractive enough, after being cut and polished, to be used for personal adornment. Geochemistry, paragenesis, and wallrock alteration of the. The large mining companies of the world are focused in big deposits and the small deposits are attractive for small miners and perhaps their. Within the mine area the oldest exposed rocks are medium to thickbedded, medium to coarse. There are several places with important content of precious metals waiting for skill prospectors. Aug 28, 2007 hematite occurs as disseminated patches in stage 3 wall. Hydrothermally altered volcanic and intrusive rocks mainly andesite and monzonite.
Inrnooucrron professor kerr is one of the foremost students of hydrothermal wall rock alteration and has long shown friendly and helpful interest in anacondas study of the ore deposit at butte, montana. Mineral alteration refers to the various natural processes that alter a minerals chemical composition or crystallography mineral alteration is essentially governed by the laws of thermodynamics related to energy conservation, relevant to environmental conditions, often in presence of catalysts, the most common and influential being water h 2 o the degree and scales of time in which. Towards the sericite zone feldspars are totally obliterated, whereas towards the outer fringe they have generally survived complete alteration, being attacked only along grain. Propyfitic alteration this is a complex alteration. Geochemical fingerprinting of carbonate wall rock alteration at major base metal sulphide deposits in the otavi mountain land, namibia. The spencer method of slope stability analysis was used to assess the stability of the wall using the same rock mass parameters as in the udec analysis. Pdf gold at the sheba gold mine is found in a variety of rocks, the most important being the schists and. Causes of rock deformation stress pressure placed on rocks strain deformation of the rock strength rock resistance to deformation brittle deformation the rocks break or fracture. Redirock wall this program is used for designing advanced retaining walls using redirock retaining wall systems usa. For masonry retaining wall, the depth of wall is raised along with height as masonry withstands the lateral pressure by its weight. Wall rock country rock alteration is found in all hard rock mining districts and has been caused by hydrothermal solutions in the past history of the region. The study of wallrock alteration phenomena around slate belthosted gold deposits can provide valuable information regarding the physicochemical conditions of the orebearing fluids and the timing relationships between deformation, peak metamorphism, granitoid emplacement and mineralisation.
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