Quartz monzonite

The amli pluton is subalkaline and calc-alkaline, and mainly diorite porphyry, granodiorite, quartz monzonite, and granite-porphyry in composition (Fig. 3). The metadiabase is alkali basalt in composition,... 

Figure 11.18 Apparent K-Ar ages of minerals from Idaho Springs Formation (Front Range, Colorado, 1350-1400 Ma) in zone subjected to contact metamorphism by intrusion of a quartz monzonite (Eldora stock, 55 Ma). Reprinted from S. R. Hart, Journal of Geology, (1964), 72, 493-525, copyright 1964 by The University of Chicago, with permission of The University of Chicago Press.

Rock Samples. Three rock types were selected as substrates basalt from the Umtanum unit in the Pasco Basin in Washington state, quartz monzonite from the Climax Stock of the Nevada Test Site, and shale (metashale) from the Eleana Formation of the Nevada Test Site. Since both the basalt and the quartz monzonite exhibited different kinds and amounts of alteration within the same rock type, two samples from each rock type were used in the experiments. However, there was insufficient material to study the interaction of the more altered of these rock types with all five actinides, therefore, only the interaction with Pu was studied. 

The quartz monzonite samples (U15E-7 and U15E-7a) were originally composed of 70-80 percent feldspar, 10-15 percent biotite, 3-8 percent quartz, and 2-8 percent opaques. Both samples have been hydrothermally altered U15E-7a being the more altered. The original feldspars in both samples have been sericitized and/or altered to clinozoisite. Secondary cal cite also occurs in both samples. Pyrite is an abundant secondary mineral and minor amounts of both epidote and chlorite replace biotite and fill fractures. 

Certain of the physical data (Table III) appear to be less than satisfactory. In general, agreement between the two types of porosity measurements is not good and the values for DC3-3600, UE15-7 and UE15-7a appear excessively large. The densities of the quartz monzonite appear unusually low, i.e., values in the range 2.6 to 2.7 were expected... 

In order to produce an aqueous solution which fulfills these criteria, 120 g each of basalt, quartz monzonite, and shale were ground to powders less than 37 m in diameter. Each of the samples was placed in two liters of distilled-deionized water which had been pre-equilibrated with an atmosphere containing 10 percent CO2, 90 percent Ar, and 10 ppm Og. The experiment was carried out in an inert atmosphere box at room temperature (26 + 2°C). Samples of the fluid (10 ml) were extracted at various times over a 35-day period and filtered (O.OSpm). Analyses for Na, K, Mg, Ca, Fe, Al, Si02 (aq). Eh, and pH were made on each sample. The experiment was terminated at the end of 846 hours and analyses for HCO3, SO4, and Cl were made on each of the fluids. 

Figure 4. Calcium released to the aqueous solution during the dissolution of powders from three rock types. fA , Eleana shale (UE-17e) (0), quartz monzonite (V15e-7) (9), umtanum basalt (DC 3-3600).

Final composition of the aqueous phase. The final compositions of the waters resulting from the three dissolution experiments have been summarized and listed together with compositions of waters from natural systems (Table VI). The experimental and natural basalt waters have very similar compositions. However, the experimental quartz monzonite water has a higher than natural K content while the shale water has higher than natural K and Na contents. The HCO3 content of each of the experimental waters is higher than the content of its natural counterpart while the oposite is true for 04. 

Figure 11. Percentage of initial concentrations of tracers left in solution as function of time for the sorption experiments with the quartz monzonite samples. C)> U O, Np (Jk), Pu Am (O), Cm.

Seepage waters from climax stock (quartz monzonite). 

Average composition of perennial springs in quartz monzonites and granodiorites of the Sierra Nevadas (56 samples). 

Figures 10, 11 and 12 show the results of the contact experiments for the basalt, shale and quartz monzonite samples. The rate of adsorption was rapid during the first two weeks and changed slowly thereafter. In these experiments Pu, Am and Cm exhibited behavior similar to the results obtained in the blank experiments. Uranium showed moderate adsorption ( 50 percent) on the basalt but only slight adsorption (10-20 percent) on the shale and quartz monzonite wafers. Neptunium showed strong adsorption (70-80 percent) on the shale and slight adsorption ( v 10 percent) on the basalt and quartz monzonite.

WoUenberg H. A. and Flexser S. (1985) The distribution of uranium and thorium in the Stripa quartz monzonite, Sweden. Uranium , 155-167. 

The mineralisation at Johnson Camp (see also Chapter 8) consists of chalcopyrite, sphalerite, bomite and pyrite. It was pyrometasomatically-introduced into limestones of the Naco Group of Upper Pennsylvanian to Lower Permian age by the nearby Tertiary Texas Canyon quartz monzonite intrusive (Cooper and Silver, 1964). The mineralisation has invaded the host rock along minor fractures and as disseminations. The mineralised zones have been partly oxidised near their suboutcrops and, adjacent to the iimumerable mineralised minor fractures, along much of their down-dip extensions. The overall... 

Burtner RL, Nigrini A, Donelick RA (1994) Thermochronology of Lower Cretaceous source rocks in the Idaho-Wyoming Thrust Belt. Bull Am Assoc Petrol Geol 78 1613-1636 Calk LC, Naeser CW (1973) The thermal effect of a basalt intrasion on fission tracks in quartz monzonite. J Geol 81 189-198... 

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