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NOAA/NGDC
WDC MGG Seafloor Series Vol I

Core Data from the Deep Sea Drilling Project


Leg :  4    Top/Bottom Interval(mm):    0/   0  Describer: Benson, W.E.
Hole:  24A  Top of Core Depth(m)   :   550.00   Rock Type: IGNEOUS
Core:   4   Sample Midpoint(m)     :   551.50   Sect/Pc #:  2/

ROCK = PLAG-PYX BASALT
       ALTERED,ONE TS HAS DISCOASTERS AND COCCOLITHS,
       COMPARE TO P. 46 IN IR;
       Texture: APHANITIC, FINE-GRAINED*

Phenocrysts- PLAGIOCLASE

             PYROXENE
             AUGITE(?), ANY PYX IN GROUNDMASS LONG GONE*

Groundmass - PLAGIOCLASE               (  >50%)
             LATHS IN 2 SIZES-LARGE + COMPARATIVELY FRESH
             ENCLOSING OTHER MINERALS AND SMALL LATHS IN
             HIGHLY ALTERED GROUNDMASS OF
             CHLORITE+SERP+SAUSSURITE(?)
             + SOME DEVITRIFIED GLASS;

             OLIVINE
             POSSIBLY SOME OL HIGHLY ALTERED TO
             CHLORITE + SERP;

             MAGNETITE

Alteration - CHLORITE
             Location: GROUNDMASS,    Replacing: OL
             Location: VEINS
             FITS ALL OBSERVABLE OPTICAL PATTERNS EXCEPT ITS
             X & Z ARE JUST ABOVE 1.56;

             SERPENTINITE
             Location: GROUNDMASS     Replacing: OL

             SAUSSURITE
             Location: GROUNDMASS
             ID UNCERTAIN;

             BIOTITE
             OBSERVED FROM POWDER ON SMEAR SLIDES,ALTERING TO
             CHLORITE;

             PYRITE
             Location: DISSEMINATED,
             Location: VEINLETS
             IN VEINS IS IN TETRAHEDRA EXCEPT FOR A POCKET
             WHICH HAS CUBES MODIFIED BY OCTRAHEDRA,
             ALTERATIONS SEEM TO HAVE OCCURRED SOON AFTER
             CRYSTALLIZATION-POSSIBLY DEUTERIC;

             CALCITE
             Location: DISSEMINATED,
             Location: VEINLETS

             ZEOLITE
             Replacing: PYX
             SMALL SPHERULES ARE PARTLY TO COMPLETELY FILLED,
             TYPICALLY THEY HAVE ISOTROPIC RIMS & A LAYER OF
             WHITE FIBROUS ZEOLITE (NATROLITE?) OR ALBITE
             AND A CENTER OF FIBROUS GREEN CHLORITE, SOME OF
             THEIR SPHERULES MAY BE REPLACEMENT OF PYX PHENOS*

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These Web pages are from the Core Data from the Deep Sea Drilling Project Legs 1-96 CD-ROM produced in 2000 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.