G103 0637A023R030370001 1-6. DU SERPENTINIZED PORPHYROCLASTIC HARZBURGITE. see comments see comments see comments see comments see comments Basement rock was recorved at the bottom of this core in Section 637A-23R-3, which includes 20 cm of yellow-red mud overlying about 80 cm of extreamly altered foliated harzburgite. The rock grades from a very leached yellow rock with elongated dissolution cavities along the foliation (at a angle of 30 degrees) to a more massive, strongly foliated green-gray peridotite. The rock is almost completely serpentinized and extensively replaced by calcite (>75% in the top few cm); vertical calcite veins are abundant near the bottom of the core, and calcite rims and replaces the pyroxene porphyroclasts. The freshest samples (637A-23R-3R, 37-40 cm and 46-48 cm) have a few relict mineral fragments (opx, cpx, chromite). The rocks are 75-80% olivine, 10-15% opx, 0-5% cpx and 1-2% chromium spinel. G103 0637A024R01000 1-5. DU SERPENTINIZED PORPHYROCLASTIC HARZBURGITE. see comments see comments see comments see comments see comments Coarse porphyroclastic harzburgite with foliation defined by the alignment of oval-shaped orthopyroxene and chromium spinel. The rock is cut by thick (1-2.5 cm) dia gonal and vertical calcite veins which appear to become more regularly spaced downcore. The bottom of Section 637A-1 and top of 637A-2 include pink-gray mud and sand with Miocene discoasters. The rock is almost completely altered (95-100%) to serpentine. A few fragments of pyroxene porphyroclasts remain. Abundant thin calcite veins dissect the rock. The rock is a pyroxene-poor harzburgite with 90% serpentine derived from olivine, < 10% orthopyroxene, 1-2% clinopyroxene, and 1% chromium spinel. It is sheared, as shown by strong alongation of orthopyroxene pseudomorphs. G103 0637A024R01060 1. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-24R-1. G103 0637A025R01000 1-12. DU SERPENTINIZED PORPHYROCLASTIC HARZBURGITE. see comments see comments see comments see comments see comments The top of this core is composed of a gray-green homogeneous foliated peridotite which displays porphyroclastic textures. It is dissected by small calcite veins which are oriented at a high angle to the foliation. The calcite often contains small inclusions of magnetite. The degree of deformation, marked by the extreme elongation of orthopyroxene, increases downward to the middle of core. This is also the case for serpentinization of the peridotite, and almost no relict primary phases are preserved. Calcite veining is not as extensive, but increases again towards base of core. The bottom sections contain pyroxene-poor harzburgite which is highly serpentinized and brecciated; a lot of serpentine rubble was recorved, with large (2-3 cm) calcite veins. G103 0637A025R02000 1-2. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-25R-1. G103 0637A025R03000 1-11. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-25R-1. G103 0637A025R04000 1-5. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-25R-4. G103 0637A025R05000 1-9. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-25R-1. G103 0637A025R06000 1-4. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-25R-1. G103 0637A026R01000 1-5. DU SERPENTINIZED PORPHYROCLASTIC HARZBURGITE. see comments see comments see comments see comments see comments This core consists of highly altered peridotite which is variably veined by calcite. The veining is especially notable at the top and the bottom of core. The veins are thick, zoned, and are coarsely crystalline with comb structures. Serpentine veining is also pervasive. The middle of core includes massive, strongly altered and sheared, pyroxene-poor harzburgite. The orthopyroxene, which constitutes less than 10% of rock, is highly elongated and strained; the clinopyroxene is rounded and often replaced by calcite. The base of the core contains brecciated serpentinite and black serpentine rubble. Many of the cobble-sized pieces contain large calcite veins. G103 0637A026R02000 1A-1H. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-26R-1. G103 0637A026R03000 1-13. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-26R-1. G103 0637A026R04000 1-8. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-26R-1. G103 0637A027R01000 1-18. DU SERPENTINIZED PORPHYROCLASTIC HARZBURGITE. see comments see comments see comments see comments see comments This core consists of moderate to highly altered and sheared peridotite(highly altered & friable near base). Part of the recovered material includes some coarse-grained peridotite sand (a result of drilling). The top of the core includes cobble or smaller sized pieces of peridotite. This becomes more massive and less altered downward. Thin sections reveal the rock to be a pyroxene-rich harzburgite which contains more and larger fragments of the primary minerals (mostly opx and cpx). The rock is black in color in the middle of the core, but heavily veined with calcite. The rock grades into a pyroxene-poor (<10%) harzburgite with local occurrences of pyroxene-rich layers(20-25% pyroxene). Some amphibole associated with the alteration of pyroxenes is observed. Shear zones increase downward. G103 0637A027R02000 1-19. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-27R-1. G103 0637A027R03000 1-6. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-27R-1. G103 0637A027R04040 1-8. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-27R-1. G103 0637A027R05000 1-12. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-27R-1. G103 0637A027R06000 1-15. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-27R-1. G103 0637A028R01000 1-13B. DU SERPENTINIZED PORPHYROCLASTIC HARZBURGITE. see comments see comments see comments see comments see comments This core consists of gray-green coarse to fine-grained porphyroclastic peridotites which are pyroxene-poor(10-15% pyroxene). The apparent foliation is about 45-50 degrees at top, steepens to 75-80 degrees mid-core, and is near vertical at the base. The rock has a well-developed foliation, which is evident in thin section (extreme elongation of opx, fragmented cpx & chromium spinel crystals which are strung out along the foliation plane). The rock becomes increasingly altered and brecciated downsection, and virtually no relict fragments of primary minerals are preserved. The color changes to red-green and black downsection. The peridotite is broken into many cobble-sized pieces which have thick calcite veins and fibrous serpentine veins. G103 0637A028R02000 1-14. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-28R-1. G103 0637A028R03000 1-15. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-28R-1. G103 0637A028R04000 1-16. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-28R-1. G103 0637A029R01000 1-22. DU ALTERED PERIDOTITE. see comments see comments see comments see comments see comments Very friable and heaviliy altered peridotite was recorved in this core. It is broken up into many pieces. The color changes from red-green to black downcore. The upper part of the core contains pieces which are cut by abundant calcite veins, but this changes downwards into pieces with no calcite veins where the rock has a vertical foliation and is highly sheared. The base of the core recovered a coarse, poorly sorted peridotite sand, which is presumably the product of drilling. No shipboard thin section were made. G103 0637A029R02125 23. DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-29R-1. G103 0637A030R01000 n/a DU SERPENTINE MUD. see comments see comments see comments see comments see comments Only a blue-gray mud was recorved in this core. It has the composition of serpentine (chrysotile and lizardite), and is presumably drill gouge material. G103 0637A030R02000 n/a DU CONTINUED. see comments see comments see comments see comments see comments See description in 103-637A-30R-1.