In Hole 1109D, two types of igneous mafic rocks were recovered, undeformed metamorphosed basalt and diabase. Most of the cored igneous rocks display a well-preserved magmatic texture. The diabases that are the most abundant rock type display a coarse-grained ophitic texture composed of poikilitic clinopyroxene including radiating, locally skeletal plagioclase laths, 1 to 2 mm long, with interstitial iron oxide grains (Pl. P1, fig. 1). The grain size of the minerals increases from top (Core 180-1109D-45R) to bottom (Section 50R-3). This is clearly visible for the plagioclase that becomes porphyroclastic up to 5-6 mm in diameter (Pl. P1, fig. 2). From Section 180-1109D-51R-1 to 51R-3, the diabase displays a grain-size reduction until the very bottom of the hole (Section 51R-4), where a basaltic texture is observed (Pl. P1, fig. 3). The basaltic samples are composed of dark brown groundmass with quenched and spherulitic structures. The microlites of plagioclase between the spherulites show split ends. This presence of basaltic levels in the diabase was interpreted as the glassy chilled margin of a second sill injection rapidly cooled at the contact with the previous diabase sill or dyke (see "Igneous and Metamorphic Petrology" in Shipboard Scientific Party, 1999a).
Little evidence of tectonic deformation is recorded in the Hole 1109D diabase. The deformation is illustrated by extensional joints crosscutting the rocks and filled with hydrothermal assemblages composed of zeolite, quartz, chlorite, and calcite (Pl. P1, fig. 4). This is consistent with the almost-continuous unfaulted character of the sedimentary sequence (given by the seismic image) that overlays the basement. Indeed, brittle faulting and fracturing in the sediment is limited to the lower part of the cored section, close to the lithologic boundary between sediments and basement. It suggests that the variation in the lithologic competency was a significant factor in controlling strain. The fault pattern results from extension, assumed to be post-middle Miocene in age (see "Structural Geology" in Shipboard Scientific Party, 1999a), compatible with the Woodlark Basin north-south extension (Célérier et al., this volume).
At Site 1118, diabase was recovered in Sections 180-1118A-70R-1 to 76R-2 below a conglomeratic unit composed of carbonate matrix containing rounded basaltic clasts (see "Lithostratigraphy" in Shipboard Scientific Party, 1999b). The rocks are slightly to moderately altered and fractured. They are coarse to fine grained, with granular to ophitic texture. Mineralogy includes fresh pyroxene, saussuritised plagioclase often overgrown with dendritic iron oxide, and, less commonly, with pyrite (Pl. P2, fig. 1). Clusters of greenish layer silicates represent pseudomorphs from olivine. Grain size varies moderately throughout the zone. However, two coarse-grained zones are present at the bottom of the cored section at Samples 180-1118A-74R-2 (Piece 5, 120-149 cm) and 76R-2 (Pieces 11 and 12, 77-89 cm) (Pl. P2, fig. 2). In these intervals, the diabase has a coarse-grained texture and minerals reach 1 to 2 mm in size with spectacular dendritic ilmenite better developed than that observed at Site 1117 (Pl. P2, fig. 2). There is an abrupt change between the granular and the coarse-grained textures (Pl. P2, figs. 2, 3).
The Site 1118 diabase is locally affected by brittle deformation characterized by the development of breccia (Pl. P2, fig. 4). This deformation occurs locally in Sections 180-1118A-71R-1 to 73R-2 (878.4-889.4 mbsf) and 74R-3 to 75R-1 and 75R-2 (900.4-907.1 mbsf). Between the brecciated zones, the diabase is undeformed and preserves a magmatic granular texture. The two brecciated zones are interpreted as fluid circulation zones responsible for the weathering of the rocks (see "Igneous and Metamorphic Petrology" in Shipboard Scientific Party, 1999a).
At Site 1117, undeformed to intensely deformed metamorphosed quartz gabbro was recovered. The gabbro shows a medium-grained granular texture (the grain size locally reaches 0.5 to 1 cm). The primary magmatic texture consists of euhedral laths of plagioclase, subhedral interstitial clinopyroxene (Pl. P3, fig. 1), and xenomorph quartz grains forming aggregates. Dendritic ilmenite is observed in some samples, although in general, samples contain skeletal ilmenite and quartz grains. Secondary mineralogy consists of zoned amphibole, chlorite, clinozoisite, zeolite quartz, and calcite. The zoned amphiboles have a brown core and a green to bluish green rim (Pl. P3, fig. 2) that is continuous with green fibrous amphiboles replacing phenocrysts of former clinopyroxene. Few biotites are developed in association with amphiboles (Pl. P3, fig. 2). Zeolite replaces plagioclase, whereas chlorite associated with pale green phrenite needles is present after both pyroxene and amphibole. Chlorite is also present in veins. In the undeformed gabbro, symplectite textures are developed at the contact between plagioclase and clinopyroxene. The symplectite consists of an intergrowth of albite and chlorite lamellae, probably representing a retrogressed association from a former plagioclase and clinopyroxene assemblage (Pl. P3, fig. 3).
The upper cored section (Sections 180-1118A-7R-1 and 9R-1) is characterized by a sheared texture of partially calcitized gabbro. Downhole, two shear zones are observed in intervals 180-1118A-11R-1, 46-55 cm, and 12R-1, 29-34 cm. In the tectonized part of the gabbro, the crushing evolved into localized cataclasite within which a dark brown matrix composed of zeolite, clay minerals, and chlorite, including also small pyroxene, amphibole, and epidote grains, are observed. A ductile shear zone made of recrystallized quartz (<0.2 mm) is present crosscutting the cataclasite (Pl. P3, fig. 4). The microscopic observation shows that during the deformation, the porphyroclastic amphiboles were retrogressed to synkinematic chlorites along their cleavage planes (Pl. P3, fig. 5). This suggests that deformation took place under greenschist facies and low pressure conditions. Successive generations of veins filled with quartz and epidote assemblages, chlorite, or calcite cut the breccia (Pl. P3, fig. 6).
At Site 1114, the rocks recovered consist of intensively deformed and metamorphosed basalt and diabase. Locally, in less deformed zones, an ophitic texture composed of poikilitic clinopyroxene including radiating plagioclase laths of 1 mm is preserved (Pl. P1, fig. 5). This texture is similar to that observed in the Hole 1109D diabase. Most of the mafic rocks recovered at Site 1114 are intensively brecciated and retrogressed (Pl. P1, fig. 6).