|
|
Core data from the Ocean Drilling Program legs 101-129
ODP hard-rock thin section description - verbose form
leg : 103 section: 06 unit/subunit :
hole: 637A top int: 077 cm observer code: GIR
core: 020R pieces: 999
rock name: Schist
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Plagioclase/feldspar present % 30 original % 30 size <1
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: percent:
replacement:
comments :
****** OVERALL COMMENTS ******
Piece number 999 is a dummy value, no piece number was given. Greenschist facies.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 023 cm observer code: EVA
core: 023R pieces: 001
rock name: Peridotite, altered
texture: Foliated, porphyroclastic
grain size: < 1.5mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Completely serpentinized.
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 30
replacement:
comments :
****** OVERALL COMMENTS ******
A couple of fragments of olivine (possibly px) otherwise chromite is the only
relict mineral. Rock is foliated and exceedingly altered (yellow in color).
Calcite preserves foliation, but late stage veins are at high angles. Otherwise
the rock is very punky. Primary mineralogy percentages are given in estimated
primary abundances.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 026 cm observer code: GIR
core: 023R pieces: 001
rock name: Serpentinized peridotite
texture: Porphyoclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Orthopyroxene present % 10 original % 10 size 0.8
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 20
replacement:
comments :
****** OVERALL COMMENTS ******
Beautiful orthopryroxene and olivine.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 037 cm observer code: EVA
core: 023R pieces: 002
rock name: Altered peridotite (pale yellow)
texture: Sheared, foliated, porphyroclastic
grain size: < 1mm - 6mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Completely serpentized.
Olivine present % 80 original % 80 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 30-40
replacement:
comments : Extensive, pervasive.
****** OVERALL COMMENTS ******
Fragments of cpx possibly olivine. Cpx-rich sample. Grains-fragments appear
brecciated and widely separated by extensive serpentinization and calcification.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 046 cm observer code: EVA
core: 023R pieces: 003
rock name: Altered peridotite
texture: Porphyroclastic, sheared
grain size: 3-4mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Almost completely altered.
Olivine present % 85 original % 85 size 2-3
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 70
replacement:
comments : Pervasive, several episodes.
****** OVERALL COMMENTS ******
Both olivine and cpx fragments, minor opx. Orthopyroxene generally serpentinized,
but pseudomorph is still recognizable. Foliation defined by pyroxene elongation
and bands(?), secondarily by veining.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 065 cm observer code: EVA
core: 023R pieces: 005
rock name: Altered yellow brown peridotite
texture: Coarse porphyroclastic, sheared
grain size: Up to 7-8 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Completely serpentinized.
Olivine present % 75 original % 75 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 40
replacement:
comments : Veins and patches of meshworked veins.
****** OVERALL COMMENTS ******
Calcite is last stage of alteration, roughly parallel to foliation.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 069 cm observer code: EVA
core: 023R pieces: 005
rock name: Altered peridotite
texture: Porphyroclastic
grain size: Up to 5-6 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Mostly altered.
Olivine present % 75 original % 75 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 60
replacement:
comments : Mesh work.
****** OVERALL COMMENTS ******
Good cpx. Heavily altered with calcite, tends to obscure texture, except where px
grains or pseudomorphs are preserved. Slide from an oriented section.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 083 cm observer code: EVA
core: 023R pieces: 006
rock name: Altered peridotite
texture: Foliated
grain size: 5 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Almost completely serpentinized.
Olivine present % 90 original % 90 size ?
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 90
replacement:
comments : Fine mesh work, includes small fragments.
****** OVERALL COMMENTS ******
Chr, ol, px fragments. More serpentine - less calcite; less cpx - more spinel.
Sample is less replaced and brecciated by calcite veins than other sections.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 021 cm observer code: EVA
core: 024R pieces: 002
rock name: Altered peridotite
texture: Porphyroclastic
grain size: Up to 5 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
95% altered to serpentine.
Olivine present % 90 original % 90 size ?
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 80
replacement:
comments : Mesh work and altered opx.
****** OVERALL COMMENTS ******
Scattered or fragments of opx, chr. Opx-poor sample, less sheared than other
sample. Foliation not as prominant, more serpentization, less calcite.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 055 cm observer code: EVA
core: 024R pieces: 004
rock name: Altered peridotite
texture: Porphyroclastic
grain size: Up to 7 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
More than 95% altered, a few fragments.
Olivine present % N/A original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 25
replacement:
comments : In veins and associated with opx
alteration.
****** OVERALL COMMENTS ******
A few olivine fragments, cpx, more chromite. Opx pseudomorphs are bent.
Alteration is complex: bastite and calcite.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 082 cm observer code: EVA
core: 024R pieces: 004
rock name: Altered peridotite
texture: Porphyroclastic
grain size: Up to 5mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Completely altered.
Olivine present % 95 original % 95 size ?
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 15
replacement:
comments : Associated with opx and in veins.
****** OVERALL COMMENTS ******
Extremely altered. Calcite is associated with alteration of opx (early, kind of
punky) and in anastomosing veins (up to 1mm); often at high angle to foliation
(roughly vertical). Most of the sample is serpentine. Oriented section.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 135 cm observer code: EVA
core: 024R pieces: 005
rock name: Altered peridotite
texture: Porphyroclastic, foliated
grain size: 2-4 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Completely serpentinized.
Olivine present % 90 original % 90 size ?
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 85
replacement:
comments : Mesh work, but preserves a foliation.
****** OVERALL COMMENTS ******
Completely altered.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 070 cm observer code: EVA
core: 024R pieces: 001
rock name: Altered peridotite
texture: Completely serpentinized
***** PHENOCRYSTS *****
***** GROUNDMASS *****
N/A present % N/A original % N/A size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 25-30
replacement:
comments : Veins and patches, coarsely crystalline.
****** OVERALL COMMENTS ******
Much of slide wiped out during grinding process. Completely altered to serpentine
and calcite.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 082 cm observer code: EVA
core: 024R pieces: 001
rock name: Altered peridotite
texture: Porphyroclastic, foliated
grain size: 2 - 5 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Relatively equant, altered to least extension.
Clinopyroxene present % 5 original % 5 size 2-3
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: N/A
replacement:
comments : At least two episodes, mesh work and
veins.
****** OVERALL COMMENTS ******
Pyroxene-rich peridotite, sheared (opx). Pyroxene occurs in bands, opx strained.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 001 cm observer code: EVA
core: 025R pieces: 001
rock name: Pyroxene-rich altered peridotite
texture: Porphyroclastic
grain size: 5-8 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Serpentinized.
Olivine present % 75-80 original % 75-80 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 20
replacement:
comments : Veins 45 degrees to foliation, and in
large patches associated with alteration
of px.
****** OVERALL COMMENTS ******
Kind of a messy sample, lots of fine grained calcite (generally associated with
alteration of px) which breaks up px fragment.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 026 cm observer code: EVA
core: 025R pieces: 008
rock name: Altered peridotite
texture: Porphyroclastic
grain size: 3-8 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Mostly altered.
Olivine present % 80 original % 80 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 15
replacement:
comments : Thin irregular veins, associated with
opx.
****** OVERALL COMMENTS ******
Tiny opx, ol remnants. Cpx? associated with opx porphyroclast.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 031 cm observer code: EVA
core: 025R pieces: 008
rock name: Altered peridotite
texture: Porphyroclastic
grain size: 5 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Completely serpentinzed.
Olivine present % 80-85 original % 80-85 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 20
replacement:
comments : Coarsely crystalline, surrounds opx in
veins (1-2 mm), at high angle to
foliation.
****** OVERALL COMMENTS ******
Good opx fragments, conchoidal on one side. No obvious cpx.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 059 cm observer code: EVA
core: 025R pieces: 008
rock name: Altered peridotite
texture: Porphyroclastic
grain size: 3-5 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 80 original % 80 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 10-15
replacement:
comments : Associated with px alteration and veins.
****** OVERALL COMMENTS ******
Fragments of ol, cpx, opx, chr. Calcite veins, coarsely crystalline with some
sort of Fe-oxide (hematite-magnetite?). Chromite-rich associated with pyroxene.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 073 cm observer code: EVA
core: 025R pieces: 008
rock name: Altered peridotite
texture: Porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Much is altered to calcite.
Clinopyroxene present % 3 original % 3 size 2
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine/magnetite percent: 90
replacement:
comments : Mesh work.
****** OVERALL COMMENTS ******
Rock not as foliated as many. Opx remnants, minor cpx and ol.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 109 cm observer code: EVA
core: 025R pieces: 008
rock name: Altered peridotite (yellow)
texture: Foliated, porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Serpentinized.
Olivine present % 85-90 original % 85-90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 30-35
replacement:
comments : Radiating and bladed, large vein (7-8mm)
coarsely crystalline.
****** OVERALL COMMENTS ******
One half of slide comprises late stage calcite veins with large radiating
clusters of crystals. Other half of slide is heavily serpentinized.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 047 cm observer code: EVA
core: 025R pieces: 001
rock name: Altered peridotite
texture: Sheared, porphyroclastic
grain size: 3 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 90-95 original % 90-95 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 25
replacement:
comments : Veins (concordant and discordant), also
associated with cpx.
****** OVERALL COMMENTS ******
Alternating serpentine and calcite veins/bands. Very sheared and altered. Some
cpx is unaltered. Can almost be called dunite with cpx. Oriented sample.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 061 cm observer code: EVA
core: 025R pieces: 001
rock name: Altered peridotite
texture: Foliated, porphyroclastic
grain size: 3-4 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 85 original % 85 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 60
replacement:
comments : Veining roughly parallel to foliation.
****** OVERALL COMMENTS ******
Orthopyroxene and olivine fragments. Heavily altered, calcite veining is
pervasive. A couple of generations; 1, alteration associated with serpentine and
alteration of px, and 2, veining. Half of slide is calcite vein parallel to
foliation.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 096 cm observer code: EVA
core: 025R pieces: 001
rock name: Altered peridotite
texture: Sheared and porphyroclastic
grain size: 1-4 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Altered.
Olivine present % 85 original % 85 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 10
replacement:
comments : Thin veins (1mm) parallel to and 45
degrees to foliation.
****** OVERALL COMMENTS ******
Fragments of brecciated cpx, ol, and spinel. Larger remnants of opx.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 114 cm observer code: EVA
core: 025R pieces: 001
rock name: Altered peridotite
texture: Porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Primary mineralogy difficult to assess because of alteration.
Orthopyroxene present % 10? original % 10? size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 25
replacement:
comments : Anastamosing veins up to 2 mm thick.
****** OVERALL COMMENTS ******
Middle of slide wiped out during grinding. Minor opx fragments, otherwise
completely altered.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 048 cm observer code: EVA
core: 025R pieces: 008
rock name: Altered peridotite
texture: Brecciated with calcite alteration
grain size: 2-3 mm up to 7 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Difficult to estimate because of pervasive alteration and brecciation of calcite.
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 60
replacement:
comments : Pervasive. See main comments.
****** OVERALL COMMENTS ******
Relict opx, ol, and cpx. Only a couple of fragments. Calcite: thin veins, thick
(2-3mm) veins which appear zoned and are surrounded by serpentine; patches
associated with opx alteration; others are irregular, broken up patches, very
irregular.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 058 cm observer code: EVA
core: 025R pieces: 008
rock name: Altered peridotite
texture: Altered porphyroclastic
grain size: Fine grained
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 15-20
replacement:
comments : Veins with crystals perpendicular to
veins.
****** OVERALL COMMENTS ******
Tiny (< 1mm) fragments of opx and ol. Greater than 99% altered.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 062 cm observer code: EVA
core: 025R pieces: 008
rock name: Altered peridotite
texture: Veined, used to be porphyroclastic
grain size: Up to 5 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Broken up.
Clinopyroxene present % 1-2 original % 1-2 size 2
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 80
replacement:
comments :
****** OVERALL COMMENTS ******
Good chromite. Minor fragments in large opx. Small cpx, ol.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 090 cm observer code: EVA
core: 025R pieces: 011
rock name: Altered peridotite (yellow)
texture: Extremely altered
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Round calcite patches?
Clinopyroxene present % 1-2 original % 1-2 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 5
replacement:
comments : Round (2-3mm) patches and veins.
****** OVERALL COMMENTS ******
Center plucked. Only relict mineral is chromite. Extremely altered.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 096 cm observer code: EVA
core: 025R pieces: 011
rock name: Peridotite
texture: Extremely altered and veined
grain size: Up to 5 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 80 original % 80 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 20
replacement:
comments : Patches (opx), thin irregular veins.
****** OVERALL COMMENTS ******
Minor relict opx. At least two episodes of serpentinization. Brecciated by
serpentine veins.
ODP hard-rock thin section description - verbose form
leg : 103 section: 04 unit/subunit :
hole: 637A top int: 024 cm observer code: EVA
core: 025R pieces: 001
rock name: Altered peridotite
texture: Sheared porphyroclastic
grain size: 5 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 75-80 original % 75-80 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 15-20
replacement:
comments : Associated with px.
****** OVERALL COMMENTS ******
Pyroxene-rich. Lots of opx fragments, variably altered to calcite. Alteration is
complex. Oriented section.
ODP hard-rock thin section description - verbose form
leg : 103 section: 04 unit/subunit :
hole: 637A top int: 099 cm observer code: EVA
core: 025R pieces: 004
rock name: Serpentinized peridotite
texture: Sheared, porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 80 original % 80 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: N/A
replacement:
comments : Thin veins.
****** OVERALL COMMENTS ******
Less calcite, calcite veins are "dirtier". Opx - extremely sheared. Opx, cpx,
chr, ol fragments. Serpentine parallels foliation.
ODP hard-rock thin section description - verbose form
leg : 103 section: 04 unit/subunit :
hole: 637A top int: 117 cm observer code: EVA
core: 025R pieces: 005
rock name: Altered peridotite
texture: Foliated
grain size: Up to 7 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Altered.
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 90
replacement:
comments : Veins and mesh texture, primarily
parallel to foliation, some cross
foliation.
****** OVERALL COMMENTS ******
Opx fragments, with thin exsolution lamellae. Late serpentinized and associated
with calcite. Pyroxene poor sample. Good chromite. Oriented section.
ODP hard-rock thin section description - verbose form
leg : 103 section: 04 unit/subunit :
hole: 637A top int: 143 cm observer code: EVA
core: 025R pieces: 005
rock name: Peridotite
texture: Sheared and altered
grain size: Up to 1.5 cm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
More than 95% altered.
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 75
replacement:
comments : Comprises most of sample.
****** OVERALL COMMENTS ******
Extremely sheared. Opx elongated by at least a factor of two. Opx, cpx, chr, ol
remnants, the rest is clean serpentine (very little calcite).
ODP hard-rock thin section description - verbose form
leg : 103 section: 04 unit/subunit :
hole: 637A top int: 146 cm observer code: EVA
core: 025R pieces: 005
rock name: Altered peridotite
texture: Porphyroclastic and sheared
grain size: Up to 1 cm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Mostly serpentinized.
Olivine present % 75 original % 75 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 90
replacement:
comments : Mesh texture and some secondary veins.
****** OVERALL COMMENTS ******
Pyroxene-rich. Quite a lot of opx, some ol and cpx fragments. Cpx - tends to be
brecciated into quite small fragments. Extremely sheared rock.
ODP hard-rock thin section description - verbose form
leg : 103 section: 05 unit/subunit :
hole: 637A top int: 011 cm observer code: EVA
core: 025R pieces: 001
rock name: Altered peridotite
texture: Porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Completely altered.
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: N/A
replacement:
comments : Zoned veins and patches, radiating
crystals.
****** OVERALL COMMENTS ******
Minor ol fragments. Alteration and calcite rims some serpentine veins, associated
with fine-grained Fe-oxide. Heavily altered. Oriented section.
ODP hard-rock thin section description - verbose form
leg : 103 section: 05 unit/subunit :
hole: 637A top int: 119 cm observer code: EVA
core: 025R pieces: 009
rock name: Altered peridotite
texture: Coarsely porphyroclastic
grain size: Up to 1 cm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Associated with orthopyroxene.
Clinopyroxene present % 25 original % 25 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 10
replacement:
comments : Late stage vein.
****** OVERALL COMMENTS ******
Pyroxene-rich sample, relatively fresh, some cpx pretty brecciated, some have
exsolution lamellae.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 036 cm observer code: EVA
core: 026R pieces: 001
rock name: Altered peridotite
texture: Altered, porphyroclastic, sheared
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Completely serpentinized.
Olivine present % 80 original % 80 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 15
replacement:
comments : Veins comprising radiating bundles.
****** OVERALL COMMENTS ******
Several episodes of serpentinization/calcite alteration. A couple of opx, cpx
remnants. Cpx is best preserved. Opx pseudomorphs show evidence of staining.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 049 cm observer code: EVA
core: 026R pieces: 001
rock name: Serpentinite
texture: Formerly porphyroclastic/sheared
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Completely serpentinized.
Olivine present % 70-75 original % 70-75 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 10
replacement:
comments : In veins, bladed crystals.
****** OVERALL COMMENTS ******
1-2 cpx/opx fragments. Prior to alteration this was a pyroxene-rich peridotite.
Opx: large and occurred in clumps/bands. Shows signs of strain, bent lamellae.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 111 cm observer code: EVA
core: 026R pieces: 005
rock name: Serpentinite
texture: Porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Altered to serpentine.
Olivine present % 85 original % 85 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 15
replacement:
comments : Sinuous veins and patches.
****** OVERALL COMMENTS ******
Foliation is not well developed.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 132 cm observer code: EVA
core: 026R pieces: 005
rock name: Altered peridotite
texture: Porphyroclastic
grain size: 2-4 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Completely altered.
Olivine present % 80 original % 80 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 15-20
replacement:
comments : Thin, branching veins.
****** OVERALL COMMENTS ******
Fragments of cpx, opx (pretty large), chr.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 042 cm observer code: EVA
core: 026R pieces: 001
rock name: Altered peridotite
texture: Porphyroclastic
grain size: Up to 5 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Serpentinized.
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 20
replacement:
comments : Lots of small veins perpendicular to
foliation.
****** OVERALL COMMENTS ******
Almost completely altered. Minor opx, cpx. Foliation defined by pyroxene
elongation. Small calcite veins which are perpendicular to foliation are
discontinuous.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 066 cm observer code: EVA
core: 026R pieces: 001
rock name: Altered peridotite
texture: Sheared, porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Altered.
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 10
replacement:
comments : Veins (irregular).
****** OVERALL COMMENTS ******
Cpx, opx, chr fragments.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 083 cm observer code: EVA
core: 026R pieces: 001
rock name: Porphyroclastic altered peridotite
texture: Porphyroclastic
grain size: 3-4 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Tiny fragments.
Olivine present % 85-90 original % 85-90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 80
replacement:
comments : Mesh work, more massive patches
associated with opx.
****** OVERALL COMMENTS ******
Cpx, ol?, opx, chr fragments. Opx is elongated by a factor of 2-3.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 117 cm observer code: EVA
core: 026R pieces: 001
rock name: Peridotite
texture: Sheared, porphyoclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 30
replacement:
comments : Small veins parallel to foliation.
****** OVERALL COMMENTS ******
Minor cpx and opx fragments. Oriented sample.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 006 cm observer code: EVA
core: 026R pieces: 001
rock name: Altered peridotite
texture: Sheared, porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Serpentinized.
Olivine present % 85-90 original % 85-90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: N/A
replacement:
comments : Veins subparallel to foliation.
****** OVERALL COMMENTS ******
High cpx/opx. Chromite rich.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 096 cm observer code: EVA
core: 026R pieces: 010
rock name: Altered peridotite
texture: Serpentinized
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Fractured and elongated parallel to foliation.
Chromite present % 1 original % 1 size 2-4
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 10
replacement:
comments : 1-2 mm veins.
****** OVERALL COMMENTS ******
Rock is completely serpentinized. Calcite veins are relatively thin and calcite
is restricted to vein occurrences.
ODP hard-rock thin section description - verbose form
leg : 103 section: 04 unit/subunit :
hole: 637A top int: 067 cm observer code: EVA
core: 026R pieces: 008
rock name: Altered peridotite (black)
texture: Porphyroclastic
grain size: Up to 5-6 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Sometimes associated with opx.
Clinopyroxene present % 2 original % 2 size 2-3
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 10
replacement:
comments : Thin veins associated with pyroxene,
usually with serpentine.
****** OVERALL COMMENTS ******
Good cpx, opx (elongated by factor of 2-3). Oriented sample.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 095 cm observer code: EVA
core: 027R pieces: 015
rock name: Altered peridotite
texture: Porphyroclastic, brecciated
grain size: 7 mm (opx)
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Serpentinized.
Olivine present % 80 original % 80 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: N/A
replacement:
comments : Veins, associated with px, in large
serpentine veins.
****** OVERALL COMMENTS ******
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 113 cm observer code: EVA
core: 027R pieces: 015
rock name: Altered peridotite
texture: Porphyroclastic - foliated
grain size: 2-5 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Serpentinized.
Olivine present % 75 original % 75 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 5
replacement:
comments :
****** OVERALL COMMENTS ******
Cpx, chr, ol, opx fragments. Pyroxene and chromite-rich sample. Pyroxene in
bands.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 128 cm observer code: EVA
core: 027R pieces: 015
rock name: Black, altered peridotite
texture: Fine grained porphyroclastic
grain size: 2-3 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Clinopyroxene present % 5 original % 5 size 1
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 5
replacement:
comments : Veins perpendicular around pyroxene.
****** OVERALL COMMENTS ******
Cpx fragments. Little calcite.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 007 cm observer code: EVA
core: 027R pieces: 002
rock name: Altered peridotite/serpentinite
texture: Fine grained porphyroclastic
grain size: 2 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 5
replacement:
comments : Mixed with serpentine, kind of dirty.
****** OVERALL COMMENTS ******
Sheared and brecciated. Pyroxene pseudomorphs still evident. Serpentine veins and
opx pseudomorphs appear broken/rotated and brecciated. Serpentine preserves a
foliation/schistosity. Rock is completely altered.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 020 cm observer code: EVA
core: 027R pieces: 004
rock name: Altered peridotite
texture: Porphyroclastic
grain size: 5 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 85-90 original % 85-90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 30
replacement:
comments : Mostly in large vein, zoned.
****** OVERALL COMMENTS ******
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 068 cm observer code: EVA
core: 027R pieces: 009
rock name: Altered peridotite (black)
texture: Coarse porphyroclastic
grain size: 5-7 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Altered.
Olivine present % 85-90 original % 85-90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 10
replacement:
comments : Discordant veins, kind of dirty.
****** OVERALL COMMENTS ******
Some opx shows signs of strain. Pyroxene-rich sample. Relatively fresh.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 122 cm observer code: EVA
core: 027R pieces: 015
rock name: Altered peridotite
texture: Sheared, porphyroclastic
grain size: Up to 5-6 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Strung out along foliation.
Clinopyroxene present % 5 original % 5 size 3
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 95
replacement:
comments :
****** OVERALL COMMENTS ******
Lots of cpx. Oriented sample.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 126 cm observer code: EVA
core: 027R pieces: 016
rock name: Altered peridotite (black)
texture: Porphyroclastic
grain size: 2-4 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 80 original % 80 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 5
replacement:
comments : Fine-grained in veins with pyroxene.
****** OVERALL COMMENTS ******
Opx, cpx, chr, ol? fragments. Quite a bit of pyroxene, occurs in bands. Chromite
associated with pyroxene. Very little calcite, therefore minerology is less
obscured.
ODP hard-rock thin section description - verbose form
leg : 103 section: 04 unit/subunit :
hole: 637A top int: 053 cm observer code: EVA
core: 027R pieces: 001
rock name: Altered peridotite
texture: Porphyroclastic
grain size: 3-4 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Mostly serpentinized.
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: <5
replacement:
comments : A few thin veins.
****** OVERALL COMMENTS ******
Relatively fresh. Serpentine, opx indicate shear.
ODP hard-rock thin section description - verbose form
leg : 103 section: 04 unit/subunit :
hole: 637A top int: 124 cm observer code: EVA
core: 027R pieces: 005
rock name: Altered peridotite
texture: Porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 15
replacement:
comments :
****** OVERALL COMMENTS ******
Pyroxene-poor sample. Almost all pyroxene is replaced by calcite and serpentine.
One ol fragment (coated with ferric-iron). Most of the rock is a serpentine-oxide
mix. Very altered.
ODP hard-rock thin section description - verbose form
leg : 103 section: 05 unit/subunit :
hole: 637A top int: 010 cm observer code: EVA
core: 027R pieces: 001
rock name: Altered peridotite
texture: Porphyroclastic
grain size: 3-5 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Completely altered.
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 10
replacement:
comments : Thin rims on opx, cross-cutting veins,
replaces px.
****** OVERALL COMMENTS ******
Some relict opx.
ODP hard-rock thin section description - verbose form
leg : 103 section: 05 unit/subunit :
hole: 637A top int: 054 cm observer code: EVA
core: 027R pieces: 007
rock name: Altered peridotite
texture: Porphyroclastic
grain size: 4-8 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 80 original % 80 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 10
replacement:
comments : Replacement of pyroxene.
****** OVERALL COMMENTS ******
Minor cpx fragments with amphibole? Most opx serpentinized. Almost completely
altered.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 010 cm observer code: EVA
core: 028R pieces: 001
rock name: Altered peridotite
texture: Porphyroclastic
grain size: 4-10 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Mostly replaced by px.
Clinopyroxene present % 2-3 original % 2-3 size 4
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Serpentine percent: 85
replacement:
comments : Some thin cross-cutting veins.
****** OVERALL COMMENTS ******
Very sheared rock. Relatively pyroxene-poor sample. Good cpx, extremely stretched
opx. Olivine fragments? Almost completely serpentinized.
ODP hard-rock thin section description - verbose form
leg : 103 section: 01 unit/subunit :
hole: 637A top int: 081 cm observer code: EVA
core: 028R pieces: 009
rock name: Altered peridotite
texture: Porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Serpentinized.
Olivine present % 75 original % 75 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 15
replacement:
comments : Large vein (2-3mm), replaces px.
****** OVERALL COMMENTS ******
Sheared, tension gashes filled with opx.
ODP hard-rock thin section description - verbose form
leg : 103 section: 02 unit/subunit :
hole: 637A top int: 017 cm observer code: EVA
core: 028R pieces: 001
rock name: Altered peridotite
texture: Porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 90 original % 90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 5
replacement:
comments : Thin vein.
****** OVERALL COMMENTS ******
Good cpx, opx-rich.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 069 cm observer code: EVA
core: 028R pieces: 012
rock name: Serpentine breccia
texture: Brecciated
***** PHENOCRYSTS *****
***** GROUNDMASS *****
N/A present % N/A original % N/A size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 50
replacement:
comments :
****** OVERALL COMMENTS ******
Completely replaced by serpentine and calcite. Very brecciated. Cut by late stage
calcite.
ODP hard-rock thin section description - verbose form
leg : 103 section: 03 unit/subunit :
hole: 637A top int: 094 cm observer code: EVA
core: 028R pieces: 013
rock name: Very altered peridotite
texture: Porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Orthopyroxene present % 10 original % 10 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 70
replacement:
comments : Finely crystalline calcite.
****** OVERALL COMMENTS ******
Completely altered, replaced by calcite. Some opx pseudomorphs.
ODP hard-rock thin section description - verbose form
leg : 103 section: 04 unit/subunit :
hole: 637A top int: 148 cm observer code: EVA
core: 028R pieces: 016
rock name: Altered peridotite
texture: Porphyroclastic
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Olivine present % 85-90 original % 85-90 size N/A
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 50
replacement:
comments :
****** OVERALL COMMENTS ******
Heavily veined, replaced with calcite. Good opx, cpx, (ol?) fragments. Most
calcite is perpendicular to foliation and is pervasive. Rock is heavily altered.
ODP hard-rock thin section description - verbose form
leg : 103 section: 05 unit/subunit :
hole: 637A top int: 010 cm observer code: EVA
core: 028R pieces: 001
rock name: Altered peridotite
texture: Porphyroclastic
grain size: 3 mm
***** PHENOCRYSTS *****
***** GROUNDMASS *****
Rounded/fractured, replaced by calcite.
Clinopyroxene present % 3 original % 3 size 3
****** VESICLES *****
Type: Vesicles %: 0
****** SECONDARY MINERALIZATION ******
mineral name: Calcite percent: 70
replacement:
comments :
****** OVERALL COMMENTS ******
Some cpx fragments. Rock is extensively replaced and brecciated by calcite. Only
cpx, random replacement and orientation of veinlets.
introduction | data types | geographic areas | legs/sites/holes | sites/holes
These Web pages are from the Core Data from the Ocean Drilling Program Legs 101-129 CD-ROM produced in 2001 by the U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Environmental Satellite, Data, and Information Service, National Geophysical Data Center, and collocated World Data Center for Marine Geology and Geophysics, Boulder. Data were compiled in cooperation with the U.S. Science Support Program, the Joint Oceanographic Institutions, Inc., and the U.S. National Science Foundation. Please see the NGDC privacy, disclaimer, and copyright notices. Additional ocean drilling data are available from NGDC and from the ODP/IODP.
questions to: carla.j.moore@noaa.gov