Results 61 to 70 of about 85,736 (331)

Minerals in Afghanistan : rare-metal deposits [PDF]

, 2007
In Afghanistan rare metals (lithium, caesium, tantalum and niobium) occur in three main deposit types: pegmatites, mineralised springs and playa-lake sediments (Figure 1).
Benham, Antony John, Coats, Stan
core  

Geological and geotechnical challenges on the Great Dyke of Zimbabwe and their impact on hardrock pillar design

Deep Underground Science and Engineering, EarlyView.
The Great Dyke of Zimbabwe is notable for its rich platinum group metal deposits but poses significant geological and geotechnical challenges due to its complex rock types and structural features. Traditional pillar design methods are insufficient for addressing these complexities; the study suggests incorporating advanced techniques such as machine ...
Tawanda Zvarivadza, Hendrik Grobler, Moshood Onifade, Manoj Khandelwal   +3 more
wiley   +1 more source

An Assessment of the Magmatic Conditions of Late Neoproterozoic Collisional and Post-collisional Granites From the Guéra Massif, South-Central Chad

Frontiers in Earth Science, 2020
The Guéra Massif, in South-Central Chad hosts granitic rocks that were emplaced during distinct intervals (595–590; ∼570; ∼560 Ma) of the Late Ediacaran Central African Orogenic Belt.
Chi Thi Pham, J. Gregory Shellnutt, Meng-Wan Yeh, Yoshiyuki Iizuka   +3 more
doaj   +1 more source

The Proterozoic granitoids of Finland: Granite types, metallogeny and relation to crustal evolution [PDF]

Bulletin of the Geological Society of Finland, 1986
The granitoids are divided into four main groups: synkinematic (1860‒1930 Ma, most commonly 1870‒1890 Ma), late-kinematic (1800‒1850 Ma) and postkinematic (ca. 1800 Ma) Svecokarelian granitoids, and anorogenic rapakivi granites (1540‒1700 Ma).
P.A. Nurmi, I. Haapala
doaj   +1 more source

Numerical investigation on the influence of mesoscopic deformation on contact area and hydraulic aperture to fracture seepage

Deep Underground Science and Engineering, EarlyView.
Fluid flow through a single fracture is commonly described by the cubic law. However, deviations from this model are expected because natural fracture surfaces are rough and in contact with each other in discrete regions. In this study, the interactions between fracture closure, contact area, and hydraulic characterization of mesoscopic‐scale rough ...
Chenghao Han, Yuanlin Bai, Weijie Zhang, Jicheng Zhang, Hongfa Ma, Weiye Li   +5 more
wiley   +1 more source

New geochemical and isotopic constraints on the genesis of the Oliveira Azeméis granitoid melts (Porto-Tomar Shear Zone, Iberian Variscan Chain, Central-Western Portugal). [PDF]

, 2012
The Porto-Tomar Shear Zone (PTSZ) is a very important tectonic structure that separates, in central-western Portugal, two of the major tectonic units of the Iberian Variscan Chain: the Ossa-Morena Zone, to the west, and the Central Iberian Zone, to the ...
Gonçalves, A., Mendes, M.H., Moita, P., Santos, J.   +3 more
core   +1 more source

Effects of water and fluorine on the viscosity of albite melt at high pressure: a preliminary investigation [PDF]

, 1985
The viscosities of fluorine- and water-bearing melts based on albite composition have been determined at 7.5, 15 and 22.5 kbar by the falling-sphere method. All melt viscosities decrease isothermally with increasing pressure.
Arndt, Bartlett, Berman, Bjørn O. Mysen, Bottinga, Brown, Burnham, Christiansen, Clark, Compston, Dingwell, Donald B. Dingwell, Gill, Hazen, Huang, Jurewicz, Kogarko, Kushiro, Kushiro, Kushiro, Manning, Mysen, Mysen, Navrotsky, Piwinskii, Rabinovich, Rau, Riebling, Scarfe, Seifert, Shaw, Shaw, Shaw, Sleep, Spera, Stolper, Taylor, Turcotte, Tuttle, Vernon, Waff, White   +41 more
core   +1 more source

Review and prospects of shear test of bolted rock joints

Deep Underground Science and Engineering, EarlyView.
The laboratory shear test equipment, test method, and numerical simulation of bolted rock joints were summarized. The shortcomings and limitations of the current research were analyzed, and the research prospects were proposed. Abstract Rock bolting is a critical approach in geotechnical engineering for supporting weak rocks.
Shulin Ren, Fan Yang, Manchao He, Yong Yuan, Zhigang Tao   +4 more
wiley   +1 more source

Plagioclase-mantled K-feldspar in the Carboniferous porphyritic microgranite of Altenberg-Frauenstein, Eastern Erzgebirge / Krušné Hory [PDF]

Bulletin of the Geological Society of Finland, 2002
The Upper Carboniferous porphyritic microgranite of Altenberg-Frauenstein, formerly known as Granitporphyr (Dalmer 1896) and here abbreviated as GP, forms a 36 km long and up to 18 km wide complex of ring dykes related to the Teplice-Altenberg caldera in
A. Müller, R. Seltmann
doaj   +1 more source

Field Studies of the Archean in Grand Canyon [PDF]

, 1933
The oldest rocks of Arizona which form the precipitous walls of the inner or granite gorge of the Grand Canyon have never received the intensive study that has been given to their counterparts over the great northeastern plains of Canada, in the ...
Campbell, Ian, Maxson, John
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