Leg : 13 Top/Bottom Interval(mm): 0/ 0 Describer: Hsu, K.
Hole: 121 Top of Core Depth(m) : 861.00 Rock Type: METAMORPHIC
Core: 24 Sample Midpoint(m) : 864.10 Sect/Pc #: CC/PCE A1
ROCK = CORDIERITE-BIOTITE-FELDSPAR HORNFELS
SOURCE IS IR,PIECE NUMBER ASSIGNED BY AUTHOR;
Texture: LAYERED*
Groundmass - CORDIERITE ( 40%)
Morphology: SUBHEDRAL-ANHEDRAL
FELDSPAR ( 30%)
Morphology: ANHEDRAL
POTASH FELDSPAR,OCCURS INTERSTITIALLY WITH
CORDIERITE;
BIOTITE ( 20%)
Morphology: PLATE AGGREGATES+
Morphology: SEMI-PARALLEL BANDS
REDDISH-BROWN;
PLAGIOCLASE ( 10%)
Morphology: SUBHEDRAL
ALBITE TWINNED,OCCURS IN SUBHEDRAL AGGREGATES AND
AS DISCRETE SUBHEDRAL XTLS,INTERLAYERED IN THE
HORNFELS ARE THIN STRINGERS OF CHLORITE-SERICITE
AGGREGATES ACCOMPANIED BY BIOTITE,PLAG AND MAGN*
Alteration - CHLORITE ( <1%)
Replacing: GARNET
THE CHLORITE AGGREGATES SEEM TO BE PSEUDOMORPHS
AFTER LARGE GARNET XTLS UP TO 5MM IN DIAMETER*
SERICITE ( <1%)
Leg : 13 Top/Bottom Interval(mm): 0/ 1 Describer: Hsu, K.
Hole: 121 Top of Core Depth(m) : 861.00 Rock Type: METAMORPHIC
Core: 24 Sample Midpoint(m) : 864.00 Sect/Pc #: CC/PCE A2
ROCK = MICACEOUS QUARTZ-FELDSPAR GNEISS
SOURCE IS IR;
Groundmass - QUARTZ ( 50%)
Size(mm): TO 1 Morphology: ANHEDRAL
GRANOBLASTIC,UNDULATORY EXTINCTION,VARIABLE SIZES;
FELDSPAR ( 25%)
Morphology: SUBHEDRAL-NEARLY EUHEDRAL
POTASH FELDSPAR,PORPHYROBLASTIC.TWINNING IS
PRESENT IN SOME AND MINUTE INCLUSIONS ARE COMMON.
PORPHYROBLASTS ARE MORE THAN 2MM LONG;
BIOTITE ( 8%)
REDDISH BROWN AND SHOWS SIGNS OF BEING DEFORMED;
MUSCOVITE ( 5%)
WHITE MICAS ARE PRESENT BOTH AS LEPIDOBLASTIC
FLAKES AND AS SERICITIC AGGREGATES REPLACING
POTASH FELDSPAR OR GARNET;
PLAGIOCLASE
ANDESINE,TWINNED AND SLIGHTLY ZONED;
GARNET
Size(mm): TO 1.5
PARTIALLY OR WHOLLY ALTERED DURING RETROGRADE
METAMORPHISM;
AMPHIBOLE
Size(mm): <.5 Morphology: SLENDER XTLS
BLUE-GREEN AMPHIBOLE WHICH IS STRONGLY PLEOCHROIC
ACTINOLITE;
OPAQUE MINERALS
OPAQUE FE-MINERALS,THE MAJOR CONSTITUENTS OF THE
METAMORPHIC ROCK INDICATE THAT THIS MEDIUM-GRAINED
PLUTONIC ROCK WAS XTLLIZED AS A GNEISS UNDER THE
CONDITIONS OF AMPHIBOLITE-FACIES METAMORPHISM,THE
ROCK WAS ALTERED AGAIN DURING A LATER EPISODE,
PRODUCING THE ACTINOLITE-CHLORITE-SERICITE
ASSEMBLAGE,THIS IS INDICATIVE OF RETROGRADE
CHANGES UNDER THE CONDITIONS OF THE GREENSCHIST
FACIES*
Alteration - SERICITE
Replacing: POTASH FELDSPAR,GARNET
CHLORITE
PROTECTIVE RIM OF AGGREGATES IS PRESENT AROUND
SOME OF THE ALTERED XTLS;
SERICITE
Leg : 13 Top/Bottom Interval(mm): 0/ 2 Describer: Hsu, K.
Hole: 121 Top of Core Depth(m) : 861.00 Rock Type: METAMORPHIC
Core: 24 Sample Midpoint(m) : 864.00 Sect/Pc #: CC/PCE B1
ROCK = GRANODIORITE
ALTERED,SOURCE IS IR;
Groundmass - FELDSPAR ( 45%)
Morphology: EUHEDRAL
ALTERED TO VERY FINE GRAINED SERICITIC AGGREGATES,
THEY MAY HAVE BEEN POTASH-FELDSPAR,LARGEST XTL IS
MORE THAN 2MM;
QUARTZ ( 40%)
Morphology: ANHEDRAL
UNDULATORY EXTINCTION AND FRACTURES,LARGEST GRAIN
IS APPROX 3MM;
PLAGIOCLASE ( 10%)
MUSCOVITE ( 5%)
Size(mm): 1 Morphology: FLAKES
PROBABLY A PRIMARY MINERAL,ON THE OTHER HAND
SERICITIC AGGREGATES ARE OBVIOUSLY REPLACEMENT
PRODUCTS DURING SECONDARY ALTERATION,TRACES OF
CHLORITE AND MAGN HAVE ALSO BEEN RECOGNIZED,THIS
ROCK BELONGS TO A GNEISS BASEMENT,THE SECONDARY
ALTERATION MAY HAVE BEEN RELATED TO A LATER
OROGENIC EVENT*
Alteration - SERICITE
Replacing: FELDSPAR
Leg : 13 Top/Bottom Interval(mm): 0/ 3 Describer: Hsu, K.
Hole: 121 Top of Core Depth(m) : 861.00 Rock Type: METAMORPHIC
Core: 24 Sample Midpoint(m) : 864.00 Sect/Pc #: CC/PCE B2
ROCK = BIOTITE-PLAGIOCLASE GNEISS
SOURCE IS IR,THIS SPECIMEN IS A METAMORPHIC ROCK OF
AMPHIBOLITE FACIES;
Groundmass - PLAGIOCLASE ( 60%)
TWINNED, COMP CALCIC ANDESINE OR
LABRADORITE;
BIOTITE ( 40%)
REDDISH-BROWN;
APATITE ( TR%)
SPHENE ( TR%)
Leg : 13 Top/Bottom Interval(mm): 0/ 4 Describer: Hsu, K.
Hole: 121 Top of Core Depth(m) : 861.00 Rock Type: METAMORPHIC
Core: 24 Sample Midpoint(m) : 864.00 Sect/Pc #: CC/PCE B3
ROCK = DIOPSIDIC BIOTITE-QUARTZ SCHIST
AMPHIBOLITE FACIES,SOURCE IS IR;
Groundmass - QUARTZ ( 65%)
FINE GRAINED;
BIOTITE ( 25%)
Size(mm): .1-.2 Morphology: FLAKES
CONSIDERABLY FINER THAN IN 121-24-CC-B2;
DIOPSIDE ( 5%)
FELDSPAR ( 5%)
POTASH FELDSPAR,RELICT GARNET XTLS BROKEN AND
REPLACED BY BIOTITE HAVE ALSO BEEN IDENTIFIED*
Leg : 13 Top/Bottom Interval(mm): 0/ 5 Describer: Hsu, K.
Hole: 121 Top of Core Depth(m) : 861.00 Rock Type: METAMORPHIC
Core: 24 Sample Midpoint(m) : 864.00 Sect/Pc #: CC/PCE B4
ROCK = GRANODIORITE
ALTERED,SOURCE IS IR;
Groundmass - QUARTZ ( 50%)
Morphology: ANHEDRAL
UNDULATORY EXTINCTION AND THOROUGHLY FRACTURED;
PLAGIOCLASE ( 15%)
Morphology: EUHEDRAL
ALMOST COMPLETELY ALTERED TO VERY FINE GRAINED
SERICITE AGGREGATES,THE SERICITE AGGREGATES APPEAR
TO BE REPLACEMENT PRODUCTS PRODUCED DURING
SECONDARY ALTERATION*
Alteration - SERICITE
Replacing: PLAG
THIS IS PIECE B4*
Leg : 13 Top/Bottom Interval(mm): 0/ 6 Describer: Hsu, K.
Hole: 121 Top of Core Depth(m) : 861.00 Rock Type: METAMORPHIC
Core: 24 Sample Midpoint(m) : 864.00 Sect/Pc #: CC/PCE B5
ROCK = MUSCOVITE-GRANODIORITE GNEISS
SOURCE IS IR,THIS ROCK,EITHER AN ORTHOGNEISS OR A
PARAGNEISS,BELONGS TO A PART OF AMPHIBOLITE-FACIES
XTLLINE COMPLEX;
Groundmass - FELDSPAR ( 30%)
Size(mm): TO 2 Morphology: SUBHEDRAL
POTASH FELDSPAR,CHARACTERIZED BY ITS CARLSBAD
TWINNING;
QUARTZ ( 40%)
Morphology: ANHEDRAL
SHOWS UNDULATORY EXTINCTION;
MICAS ( 20%)
WHITE MICAS,INCLUDE BOTH MUSCOVITE FLAKES UP TO
1MM LONG AND VERY FINE GRAINED SERICITE AGGREGATES
THE LATTER BEING COMMON ALTERATION PRODUCTS OF
FELDSPARS;
PLAGIOCLASE ( 5%)
SLIGHTLY ZONED;
EPIDOTE ( TR%)
MAGNETITE ( TR%)
SPHENE ( TR%)
Alteration - CHLORITE ( TR%)
THIS IS PIECE B5*
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