Rocks plutonic

Tiefebene,/. low plain, lowland, tiefeingreiiend, a. penetrating thoro(ugb tiefen, v.t. deepen deep-draw. cup. Tiefen-gestein, n. plutonic rock, lehre, /., -messer, m. depth gage. -schSrfe, /. (Pho tog.) depth of focus. 

The ore deposits can be classed into two types based on the types of associated metals Au-Ag rich deposits (Type A) from which An and Ag are produced as main products, and base metal (Cu, Pb, Zn, Mn, (Sn), (W), (Bi), (Mo), (Sb)) rich deposits (Type B) from which Au and Ag are recovered as byproducts. The deposits are associated with felsic and intermediate volcanic rocks but generally not with felsic plutonic rocks. In Japan Au-Ag deposits associated with granitic rocks (e.g., Au-Ag vein-type deposits in Kitakami) occur commonly. However, these plutonic-type deposits are not described here. 

In contrast, in Southwest Japan, polymetallic veins (so-called xenothermal-type deposits in the sense of Buddington (1935) or subvolcanie hydrothermal type in the sense of Cissartz (1928, 1965) and Schneiderhohn (1941, 1955) occur. Examples of these deposits are Ashio, Tsugu, Kishu and Obira. All these vein-type deposits have formed at middle Miocene age in western part of Tanakura Tectonic Line under subaerial environment. In these deposits, many base-metal elements (Sn, W, Cu, Pb, Zn) and small amounts of Au and Ag are concentrated. These deposits are associated with felsic volcanic and plutonic rocks along the Median Tectonic Line (MTL) or south of MTL. 

Figure 1.166. Distribution or initial Sr/ Sr (r, ) for the Cretaceous-Paleogene plutonic rocks. Open squares gabbros open circles granites. Numbers indicate the last two or three digits of r, values. Solid squares and solid circles imply the magnetite-series open squares and open circles the ilmenite-series. (Shibata and Ishihara, 1979).

Shibata, K. and Ishihara, S. (1979) Initial Sr/ Sr ratios of plutonic rocks from Japan. Contrib Min. Petrol,... 

Oliveros, V., Feraud, G. Aguire, L., Fornari, M., Morata, D. 2006. The Early Andean Magmatic Province (EAMP) ArmAr dating on Mesozoic volcanic and plutonic rocks from the Coastal Cordillera, northern Chile. Journal of Volcanology and Geothermal Research, 157, 31-330. 

PiERCEY, S.J. et al. 2008. Syn-volcanic and Younger Plutonic Rocks from the Blake River Group Implications for Regional Metallogenesis. Economic Geology, 103, 1243-1268. 

Plutonic rock classification by petrologic means is a simple procedure involving the use of Streckeisen ternary diagrams. Unfortunately, classification suffers from modal estimation errors involving visual estimates, or representativity issues from point counts or image analysis procedures applied to thin sections or slabs of insufficient size. 

Plutonic rocks from the Emerald Lake pluton, Yukon, comprise four phases (/) augite syenite, (//) hornblende quartz... 

Unconformity-related U deposits account for more than 33% of the world uranium resource due to their tremendous grade and tonnage. Most of them occur in the McArthur Basin (Northern Territory, Australia) and in the Athabasca Basin (Saskatchewan, Canada). The ore is commonly found close to the interface between Archaean to lower Proterozoic metamorphic and plutonic rocks, and unconformably overlying Proterozoic sandstones. Basement-rooted graphitic reverse faults are also important structural controls. 

In addition to the examples listed above, uranium mineralization occurs in several other geological settings in and around the CMB, including within granitoid plutonic rocks and as possible syngenetic mineralization in felsic volcanic rocks of both the Aillik and Bruce River groups. Pegmatite-hosted uranium mineralization is also known in deeper-level reworked Archean basement terranes. 

Many granitic plutonic rocks throughout the world have relatively uniform 0-contents with 5 0-values between 6 and 10%c. Granitoids at the low 0 end of the normal group have been described from oceanic island - arc areas where continental crust is absent (e.g., Chivas et al. 1982). Such plutons are considered to be entirely mantle-derived. Granites at the high end of the normal 0-group may have... 

The most often encountered thermal history by geologists is continuous cooling from a high temperature to room temperature (such as cooling of volcanic rocks, plutonic rocks, and metamorphic rocks). One of the many ways to approximate the cooling history is as follows ... 

Figure 1-19 Schematic diagram showing how Ku for the Fe-Mg order-disorder reaction varies during cooling. The arrow indicates the progression of time. The thin dashed curve shows how the equilibrium iCo varies with temperature as the system cools. The solid curve shows how iCo varies with temperature during rapid quench in a volcanic rock. The thick and long dashed curve shows how Kj) varies during slow cooling in a plutonic rock.

The formation event must be well defined and rapid. For example, the formation event of a volcanic rock (eruption of magma to the surface and cooling down of the magma) is well defined and rapid. But the formation of a plutonic rock is not well defined and is slow. 

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