Basalt unit
|
Core, section, piece
interval (cm) |
Size
(µm) |
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 µm |
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 µm |
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 µm; 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 µm; 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 µm; 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 µm; 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.