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concentrations (the rocks are dominated by anhydrous mineral assemblages but commonly . <br />contain cazbonate-filled vesicles and ocelli). While commonly porphyntic, textural varieties <br />include senate, glomeroporphyritic, and megacrystic porphyries as well as aphanitic types. <br />Figure 2: Sample of unaltered polphyritic <br />phonolite from Cresson. Note sanidine <br />phenocrysts. Groundmass composed of <br />sanidine, aegerine and magnetite. Scale baz <br />is Zcm. <br />ICJ <br />The phonolites were emplaced as dikes and stocks which fed upwazd into flows, sills and <br />laccolithic masses. They are the earliest intrusions seen cutting the volcanic breccias, but are <br />also seen outside the main diatreme as satellite intrusions and flow domes. Small populations of <br />phonolite dikes are seen cutting group $ intrusions, and possibly some group C intrusions. <br />2.4 Group B: Intermediate Alkaline Rocks: Nepheline Monzosyenites, <br />Tephriphonolites, Phonotephrites and Trachyandesites <br />This group represents a volumetrically subordinate, but important group of rocks. They have <br />intermediate silica concentrations (49-55 wt % Si07), and higher Ca, Fe and Mg abundances than <br />group A. The rocks are commonly present as porphyritic dikes and equigranulaz intrusive <br />stocks. The purphyritic varieties aze typically darker than rocks of group A, but where <br />equigranulaz, exhibit a "salt and pepper" appearance (see figure 3). Like the phonolites, the <br />rocks of group B are chiefly composed of alkali feldspar (orthoclase) and albitic plagioclase, but <br />have much greater abundances of anorthitic feldspaz, augite and hydrous mineral phases such as <br />amphibole (both sodic and keazsutitic varieties), and biotite. Accessory minerals include <br />magnetite, sphene, apatite, sodalite and nosean (Lindgren and Ransome, 1906). The abundance <br />of hydrous phases suggests that these magmas had relatively high concentrations of water, and <br />the presence of sodalite and nosean also suggest that chloride and sulfate anions were also <br />abundant in the melt. This notion is supported by the observation of liquid-rich magmatic fluid <br />inclusions with daughter crystals of salt (Lindgren and Ransome, ]906, p., 74-76). In some <br />Cripple CreeA & victor Gald mining Co, Sdrpherd Afi!lrr,/nt. <br />11D/AAIONOW-DAIf'EVOO~EMgnrtUnnrhwar!.dec 5 A>nrch 7000 <br />