The Fe-Zn Isotopic Characteristics and Fractionation Models: Implications for the Genesis of the Zhaxikang Sb-Pb-Zn-Ag Deposit in Southern Tibet

Figure 4

Hand specimen photographs and photomicrographs of representative samples from the Zhaxikang deposit. (a) Stage 1 lamellar sphalerite-pyrite-arsenopyrite and stage 2 massive sphalerite-pyrite hosted within fine-grained Mn-Fe carbonate. (b) Stage 1 lamellar and stage 2 banded Mn-Fe carbonate-sphalerite-galena ore with visible synsedimentary features including rhythmic sedimentation in the upper part and angular folding in the lower part of the sample. (c) Stage 1 lamellar sphalerite-pyrite-arsenopyrite and stage 2 massive and banded sphalerite-pyrite hosted by fine-grained Mn-Fe carbonate. The mineral assemblage is in turn cross-cut by stage 4 quartz-boulangerite veins. (d) Coarse-grained stage 2 Mn-Fe carbonate-sphalerite formed by the recrystallization of fine-grained stage 1 Mn-Fe carbonate-sphalerite. (e) Stage 2 massive coarse-grained pyrite hosted by slate. (f) Massive and brecciated stage 2 sphalerite hosted in stage 2 Mn-Fe carbonate. (g) Stage 2 massive, globular, and concentric annular sphalerite-pyrite hosted by coarse-grained Mn-Fe carbonate. (h) Stage 2 massive galena and pyrite. (i) Stage 2 massive and veined sphalerite-pyrite hosted by coarse-grained Mn-Fe carbonate. (j) Stage 1 lamellar sphalerite-pyrite-arsenopyrite and stage 2 massive sphalerite hosted by fine-grained Mn-Fe carbonate. The sample also contains a Mn-Fe carbonate druse dominated by idiomorphic columnar quartz and valentinite. (k) Stage 2 coarse-grained sphalerite-pyrite hosted by stage 2 Mn-Fe carbonate with banded textures. (l) Stage 2 sphalerite and Mn-Fe carbonate ore with typical Dal Matianite texture. (m) Disseminated stage 3 sphalerite and pyrite hosted in stage 3 quartz and calcite, and stage 3 quartz and calcite cut the slate. (n) Stage 3 brecciated sphalerite within stage 3 quartz-calcite. (o) Stage 3 sphalerite-galena veins cross-cut by stage 6 quartz-calcite veins. (p) Stage 3 sphalerite cross-cut by stage 4 quartz-boulangerite veins. (q) Stage 4 massive and needle-like boulangerite hosted by stage 4 quartz. (r) Stage 4 boulangerite-quartz. (s) Stage 5 elongate stibnite hosted by stage 5 quartz. (t) Stage 5 stibnite-cinnabar hosted by stage 5 quartz. (u) Siliceous sinter formed during the Supergene stage. (v) Ferrihydrite and sardinianite formed during the Supergene stage. (w) Stage 2 pyrite containing automorphic stage 1 arsenopyrite is replaced by later stage 2 sphalerite to form a skeletal texture. (x) Stage 3 sphalerite occurs in stage 3 quartz. (y) The emulsion-like and disseminated stage 3 chalcopyrite grains are dotted in the stage 3 sphalerite. (z) The stage 3 chalcopyrite grains are dotted among the grains of stage 3 pyrite. (aa) Stage 3 sphalerite replaced by stage 4 boulangerite that is in turn cross-cut by stage 5 stibnite. (ab) Stage 5 stibnite cross-cut by stage 6 quartz. Mcar1 = stage 1 fine-grained Mn-Fe carbonate; Apy1 = stage 1 lamellar arsenopyrite; Py1 = stage 1 lamellar pyrite; Sp1 = stage 1 lamellar sphalerite; Mcar2 = stage 2 coarse-grained Mn-Fe carbonate; Apy2 = stage 2 arsenopyrite; Py2 = stage 2 pyrite; Sp2 = stage 2 sphalerite; Gn2 = stage 2 coarse-grained galena; Py3 = stage 3 pyrite; Sp3 = stage 3 sphalerite; Gn3 = stage 3 galena; Ccp3 = stage 3 chalcopyrite; Qtz3 = stage 3 quartz; Cal3 = stage 3 calcite; Blr4 = stage 4 boulangerite; Qtz4 = stage 4 quartz; Stb5 = stage 5 stibnite; Ci5 = stage 5 cinnabar; Qtz5 = stage 5 quartz; Cal6 = stage 6 calcite; Qtz6 = stage 6 quartz; Lm = Supergene stage ferrihydrite.

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