Leg : 18 Top/Bottom Interval(mm): 0/ 0 Describer: MacLeod, N.S.
Hole: 172 Top of Core Depth(m) : 23.00 Rock Type: IGNEOUS
Core: 4 Sample Midpoint(m) : 23.10 Sect/Pc #: CC/
ROCK = GLASSY BASALT
SOURCE IS IR, GLASSY BASALT FRAGMENTS;
Texture: GLASSY, SERIAL GRADING, VARIOLITIC;
Where sampled: TUFF-BRECCIA OR PILLOW FLOW*
Phenocrysts- PLAGIOCLASE ( 4.0%)
Size(mm): .2X0.05
SHOW SLIGHT PROGRESSIVE ZONING AND HAVE MAXIMUM
NX OF 1.560 AND MAXIMUM NZ OF 1.575 INDICATING
COMPOSITION OF AN64 ON XTL RIMS TO AN75 IN CORES
OF LARGER XTLS,MAXIMUM SIZE ABOUT 0.5X0.25;
AUGITE ( 4.4%)
Size(mm): 0.1
SIZE RANGES TO 0.2MM,PLAG AND AUGITE (AND TO
LESSER EXTENT OL) OCCUR AS GLOMEROPHENOCRYSTS
WITH MAX DIAM. OF 1MM, AUGITE AND PLAG XTLS CONTAIN
MINUTE INCLUSIONS OF GLASS-SMALL GAS BUBBLES
OCCUR IN GLASS, AUGITE XTLS SHOW SMALL RANGE IN
EXTINCTION ANGLE AND ARE PROGRESSIVELY ZONED,
NY OF 1.695 AND 2V ABOUT 48 DEGREES INDICATING
COMPOSITION OF APROX MG38FE22CA40;
OLIVINE ( 0.3%)
Size(mm): 0.05
MOSTLY ALTERED TO BROWN BIREFRINGENT CLAY
MINERAL, COMP NOT DETERMINABLE BY OPTICAL
METHODS*
Groundmass - MICROCRYST GROUNDMASS ( 91.3%)
SIDEROMELANE GLASS THAT MAKES UP BULK OF FRAGMENTS
IS CLEAR AND LIGHT BROWN AND HAS R.I. OF 1.600 TO
1.603,MICROXLN MATRIX OF SOME FRAGMENTS IS
COMPOSED OF VARIOLITIC SHEAVES OF PLAG & PYX &
OPAQUE IRON-TITANIUM OXIDE AND HYDROXIDES AS WELL
AS GLASS OR ITS CLAY ALTERATION PRODUCTS, MOST
XTLS <0.01 MM WIDE BUT SHEAVES OF PLAG AND PYX
AS MUCH AS 0.1MM,TOO FINE-GRAINED FOR MINERAL
PROPORTIONS TO BE DETERMINED, PERCENTAGES OBTAINED
BY MODAL ANALYSIS (4500 COUNTS)*
Alteration - PALAGONITE
Location: CRACKS,RIMS
CRACKS AND SOME RIMS OF SIDEROMELANE LINED
BY FIBRO- OR GELPALAGONITE, IN SOME FRAGMENTS
ORIGINAL SIDEROMELANE ALTERED TO PALAG;
OPAQUE MINERALS
CLAY MINERALS
Vesicles -
Size(mm): TO 0.15
LINED BY FIBROPALAGONITE*
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