Table T7. Summary of the opaque mineralogy of basement rocks, Site 1205. 
Basalt unit
Core, section, piece
interval (cm)
Size
(Ám)
Titanomagnetite description
Estimated
modal
abundance
(%)
Other opaque minerals
Photomicrograph

197-1205A-




Clast in basal conglomerate (Unit V) 5R-2 (Piece 7, 31-33) 100 Slight maghemite development in some crystals; most crystals are 50 Ám 8-10 Trace of primary sulfide as minute bleb inclusions in primary minerals; secondary goethite is well developed; no sulfide
Clast in basal conglomerate (Unit V) 5R-2 (Piece 21, 101-103) 100 Unaltered; most crystals are 10 Ám 8-10 Goethite is well developed in patches; Fe oxyhydroxide is pervasive; no sulfide 1205A-182, 1205A-287
1 6R-2 (Piece 1A, 13-15) 100 Unaltered; rare maghemite is developed along cleavage planes and fractures; occasional ilmenite oxidation lamellae 6-8 No sulfide or Fe oxyhydroxide
1 6R-2 (Piece 4, 55-57) 50-150 Unaltered; slight development of ilmenite oxidation lamellae; rare maghemite along cleavage planes and fractures 6-8 Goethite is well developed in patches; Fe oxyhydroxide is pervasive; no sulfide
3b 7R-1 (Piece 17, 83-85) 30 Highly altered to maghemite with only a few relict cores in the larger crystals 8-10 Goethite is present; Fe oxyhydroxide is pervasive; no sulfide
3b 8R-1 (Piece 4, 59-61) 80 Unaltered; most crystals are 10 Ám; rare maghemite along cleavage planes and fractures; occasional ilmenite oxidation lamellae 10-12 Primary pentlandite as inclusions in primary minerals; trace of secondary pyrite; rare chromite(?) inclusions in olivine 1205A-192
3b 9R-2 (Piece 2A, 65-67) 200 Unaltered; most crystals are 40 Ám; ilmenite oxidation lamellae are present in crystals adjacent to veins 4-6 Fe oxyhydroxide is present adjacent to veins; no sulfide
3b 10R-2 (Piece 3E, 73-75) 80 Unaltered; no ilmenite oxidation lamellae or maghemite observed 12-15 No sulfide or Fe oxyhydroxide
3b 11R-1 (Piece 2A, 73-75) 200 Unaltered; many crystals are ~50 Ám; no ilmenite oxidation lamellae or maghemite observed 9-11 No sulfide or Fe oxyhydroxide
3b 11R-4 (Piece 1A, 42-44) 150 Unaltered; rare maghemite along cleavage planes and fractures; occasional ilmenite oxidation lamellae 10-12 No sulfide or Fe oxyhydroxide
3b 12R-2 (Piece 3A, 114-116) ~100 Unaltered; rare maghemite along cleavage planes and fractures; occasional ilmenite oxidation lamellae 10-12 No sulfide or Fe oxyhydroxide
3b 13R-3 (Piece 1F, 27-29) 100 Unaltered; occasional development of ilmenite oxidation lamellae 10-12 No sulfide or Fe oxyhydroxide 1205A-226, 1205A-227
5b 15R-2 (Piece 10, 138-140) 150 Unaltered; occasional development of ilmenite oxidation lamellae 10-12 No sulfide or Fe oxyhydroxide
5b 15R-3 (Piece 1B, 37-39) 80 Unaltered; occasional development of ilmenite oxidation lamellae 6-8 Rare pentlandite inclusions in primary minerals; secondary pyrite; no Fe oxyhydroxide
5b 16R-2 (Piece 15, 84-86) 80 Unaltered; occasional development of ilmenite oxidation lamellae 8-10 No sulfide or Fe oxyhydroxide
6 19R-2 (Piece 3, 104-106) 70 Unaltered; no ilmenite oxidation lamellae or maghemite observed 10-12 No sulfide or Fe oxyhydroxide
8a 20R-5 (Piece 3, 67-68) 150 Unaltered; rare maghemite along cleavage planes and fractures; occasional ilmenite oxidation lamellae 10-12 Rare pentlandite inclusions in primary minerals; no Fe oxyhydroxide
9 22R-1 (Piece 6A, 28-30) 200 Ilmenite oxidation lamellae are common; occasional development of maghemite along cleavage planes 9-11 No sulfide or Fe oxyhydroxide
10 23R-1 (Piece 8, 77-78) 60 Unaltered; rare ilmenite oxidation lamellae, but lots of cracking along cleavage planes 2-4 No sulfide or Fe oxyhydroxide
10 24R-2 (Piece 19, 124-130) 50 Extensive alteration to maghemite (~60%); relict titanomagnetite is present as lamellae parallel to cleavage planes; this is from a weathered flow top 4-6 Fe oxyhydroxide and goethite are pervasive; olivine is replaced by iddingsite or goethite; no sulfide 1205A-286
12b 27R-5 (Piece 5, 103-105) 150 Unaltered; occasional development of ilmenite oxidation lamellae 4-6 No sulfide or Fe oxyhydroxide 1205A-224
13b 28R-3 (Piece 1A, 4-6) 300 Development of ilmenite oxidation lamellae is extensive; rare maghemite along fractures and cleavage planes 4-6 Primary pentlandite as inclusions in primary minerals; trace of secondary pyrite; no Fe oxyhydroxide
14b 29R-2 (Piece 7A, 55-58) 50 Ilmenite oxidation lamellae are common; maghemite is present along fractures and cleavage planes and as rims 9-11 No sulfide or Fe oxyhydroxide 1205A-273
15b 30R-1 (Piece 9, 42-44) 40 Maghemite development is extensive; relict Ti-Mag zone parallel to cleavage planes 3-5 Fe oxyhydroxide is present; no sulfide 1205A-272
16 32R-2 (Piece 2H, 114-116) 100 Ilmenite oxidation is extensive and not confined to lamellae; rare maghemite along fractures and cleavage planes 4-6 No sulfide or Fe oxyhydroxide
17 33R-3 (Piece 1B, 11-13) 100 Development of ilmenite oxidation lamellae is extensive; maghemite along fractures and cleavage planes 5-7 No sulfide or Fe oxyhydroxide
18b 35R-1 (Piece 1A, 32-34) 50 Unaltered; occasional ilmenite oxidation lamellae 2-4 Cr spinel as inclusions in olivine phenocrysts and with Ti-Mag rims; no sulfide or Fe oxyhydroxide 1205A-248, 1205A-270
19b 35R-4 (Piece 1C, 77-79) 100 Development of ilmenite oxidation lamellae is extensive; partially replaced by maghemite 2-4 Cr spinel as inclusions in olivine phenocrysts and with Ti-Mag rims; no sulfide or Fe oxyhydroxide 1205A-251, 1205A-268, 1205A-269, 1205A-280, 1205A-281, 1205A-282, 1205A-288
20 36R-5 (Piece 2D, 50-51) 80 Ilmenite oxidation is extensive and not confined to lamellae; occasional maghemite along fractures and cleavage planes 9-11 No sulfide or Fe oxyhydroxide 1205A-250, 1205A-283
21 37R-5 (Piece 2C, 28-29) 50 Development of ilmenite oxidation lamellae is extensive 3-5 No maghemite, sulfide, or Fe oxyhydroxide
22 39R-1 (Piece 3F, 69-70) 100 Unaltered; rare maghemite along cleavage planes and fractures; occasional ilmenite oxidation lamellae 6-8 No sulfide or Fe oxyhydroxide
24a 41R-3 (Piece 1B, 59-61) 70 Ilmenite oxidation is extensive and not confined to lamellae; maghemite along fractures and cleavage planes is common 4-6 No sulfide or Fe oxyhydroxide
26a 41R-5 (Piece 1A, 24-26) 150 Development of ilmenite oxidation lamellae is extensive; partially replaced by maghemite along fractures, cleavage planes, and at rims 3-5 No sulfide or Fe oxyhydroxide 1205A-266, 1205A-267
27 43R-2 (Piece 2A, 58-60) 200 Ilmenite oxidation is extensive and not confined to lamellae; maghemite along fractures and cleavage planes is common 5-7 No sulfide or Fe oxyhydroxide 1205A-252, 1205A-253, 1205A-254
28a 44R-1 (Piece 5A, 87-88) 100 Most crystals 30 Ám; development of ilmenite oxidation lamellae is extensive 12-15 No maghemite, sulfide, or Fe oxyhydroxide 1205A-284
29b 44R-2 (Piece 9, 110-112) 50 Ilmenite oxidation is extensive and not confined to lamellae; maghemite is present along fractures and cleavage planes 12-15 No sulfide or Fe oxyhydroxide 1205A-264, 1205A-285
30b 45R-1 (Piece 5I, 126-128) 100 Development of ilmenite oxidation lamellae is extensive; partially replaced by maghemite along fractures, cleavage planes, and at rims 10-12 No sulfide or Fe oxyhydroxide 1205A-265

Note: Ti-Mag = titanomagnetite.