| Table 2. Field and petrologic characteristics of lithologic units within the field trip area. | ||||
| Lithologic Unit | Rock Type(s)1 | Primary Minerals2 | Accessory Minerals2 | Megascopic Field Characteristics2 |
|---|---|---|---|---|
| low-silica charnockite Yfqj |
monzogranite to quartz monzodiorite (farsundite to quartz jotunite) | Mipt (Mc), Pl, Qtz, Opx, Amph, Cpx | Ap, Ilm, Mag, Zrn, Ep, Act | medium- to very coarse-grained, massive to weakly foliated, lenticular magnetite-rich xenoliths, Af megacrysts |
| alkali feldspar granite Yaf |
alkali feldspar granite | Af, Pl, Qtz, Bt | Ttn, Fe-Ti Oxides | coarse-grained, porphyritic, massive |
| Old Rag magmatic suite Ygr |
alkali feldspar granite to syenogranite | Pt (Mc), Pl, Qtz, Opx, Grt, Bt | Ap, Ilm, Mag, Zrn, Ep, Act | medium- to very coarse-grained, massive to weakly foliated |
| garnetiferous syenogranite Ygg |
alkali feldspar granite to syenogranite | Or, Pl, Qtz, Grt, Bt, Opx | Ap, Ilm, Zrn | medium- to very coarse-grained, weakly to locally strongly foliated, medium-grained Af dikes, rare pegmatite dikes |
| leucogranite gneiss Ylgg |
alkali feldspar granite | Mept (Mc), Pl, gray Qtz, Bt | Ilm, Mag, Zrn, Ep, Ms | coarse- to very coarse-grained, strongly foliated, Mept megacrysts |
| biotite granitoid gneiss Ybg |
monzogranite to quartz monzonite and quartz monzodiorite | Mc, Pl, Qtz, Bt | Ap, Ilm, Ttn, Zrn, Ep, Chl | medium- to coarse-grained, strongly foliated |
| Flint Hill Gneiss Yfh |
syenogranite to monzogranite | Mc, Pl, Qtz, Bt, Chl | Ap, Leux, Ilm, Zrn | medium- to very coarse-grained, strongly foliated |
| foliated pyroxene granite Yfpg |
monzogranite (farsundite) | Mc, Pl, Qtz, Opx, Amph, Bt | Ap, Ilm, Zrn | medium- to coarse-grained, strongly foliated, pegmatitic dikes, Grt leucogranite dikes |
| layered granodiorite gneiss Ylgn |
granodiorite (opdalite) | Mc, Or, Pl, Qtz, Amph, Opx | Ap, Ilm, Zrn | medium- to coarse-grained, strongly foliated, gneissic layers locally folded, massive leucogranite sheets, boudins |
| pyroxene quartz diorite Ypqd |
quartz diorite (orthopyroxene quartz diorite) | Or, Pl, Qtz, Opx, Bt | Ap, Mag, Zrn | medium-grained, moderately to strongly foliated, gneissic layering |
| high-silica charnockite Ycf |
syenogranite to monzogranite (charnockite to farsundite) | Mipt, Pl, Qtz, Opx, Amph, Cpx | Ap, Ilm, Mag, Zrn, Ep, Act | coarse- to very coarse-grained, moderately to strongly foliated, locally prominent gneissic layering, Af megacrysts |
| garnetiferous granite gneiss Yg |
syenogranite to monzogranite | Mipt, Pl, Qtz, Opx, Grt, Bt, Cpx | Ap, Ilm, Mag, Zrn, Chl | medium- to coarse-grained, strongly foliated, prominent gneissic layering |
| garnetiferous gneiss Ygn |
granodiorite (opdalite)? | Af, Pl, Qtz, Gt, Opx | Ttn, Fe-Ti Oxides | fine- to coarse-grained, layered |
| (1) foliated megacrystic leucocratic granite (2) leucogranite Ylg |
alkali feldspar granite to syenogranite | 1) Mept (Mc & Or), Pl, Qtz, intergrown Bt & Chl 2) Mc, Pl, Qtz, minor secondary Bt |
Zrn, Ep, Ttn | (1): coarse-grained, strongly foliated (2): medium-grained, massive to weakly foliated Unit also includes coarse-grained leucogranite pegmatite |
1Rock types determined using molar normative compositions calculated on basis
of Fe2+/Fe(total) = 0.9 plotted on Q' vs ANOR diagram of Streckeisen and Le
Maitre (1979). Charnockitic nomenclature included in parentheses following
recommendations of Le Maitre and others (1989).
2Abbreviations: Af, alkali feldspar; Leux, leucoxene; Mipt, microperthite; Mept,
mesoperthite; Pt, perthite. Other abbreviations after Kretz (1983): Act, actinolite;
Aln, allanite; Amph, amphibole; Ap, apatite; Bt, biotite; Cal, calcite; Chl,
chlorite; Cpx, clinopyroxene; Ep, epidote; Fl, fluorite; Grt, garnet; Ilm, ilmenite;
Mag, magnetite; Mc, microcline; Or, orthoclase; Opx, orthopyroxene; Pl, plagioclase;
Qtz, quartz; Ttn, titanite; Zrn, zircon.