Olivine clinopyroxenite cumulate with postcumulus (intercumulus) plagioclase.
Tectonized harzburgite from fault slice along Lionshead Fault. No harzburgite exposed in continuous section. This sample is a strongly serpentinized harzburgite. Serpentine and opaques are the dominant phases in this thin section. Fractured, resorbed, and inclusion-rich orthopyroxenes are also present.
Serpentine comprises the bulk of this thin section, with skeletal masses of clinopyroxene and isolated granules of olivine dotting the characteristic serpentine mesh-work. The pyroxenes are larger and more complete than the olivine crystals.
Allotriomorphic plagioclase and highly-fractured olivine are the dominant minerals in this thin section. Clinopyroxene, when present, is found adjacent to olivine. Fractured zones in this rock follow olivine clusters and frequently cross-cut plagioclase crystals in swarms between nodes of granular olivine.
Granular, inequigranular gabbro containing occasional olivine crystals. Serpentine is localized to fractures. Grain shapes are very rounded and amorphous.
Hypidiomorphic, inequigranular k-feldspar and plagioclase with large clasts of chlorite which are likely pseudomorphs of hornblende. Radiating splays of chlorite are distributed randomly throughout, in addition to radiating zeolites, though the latter are confined to void spaces.
Clinopyroxene and plagioclase crystals with a hypidiomorphic granular texture. Clinopyroxene is cloudy and patchy in appearance due to alteration by a fine-grained material. Alteration by randomly-oriented, feathery chlorite pervades grain boundaries and fractures in the thin section.
Strongly serpentinized dunite. Only 5-10% olivine remains. The characteristic serpentine mesh-work texture is highly evident in this thin section.
The predominant mineral in this thin section is opaque red chert which is cross-cut by veins infilled with chlorite and serpentine. Towards the margins of the thin section is a metamorphosed basalt with a groundmass plagioclase mircolites and quartz, calcite, and chlorite in-filled vesicles and veins. According to collector David Sawyer, the interpillow red chert is an important indicator of deep sea origins.
The groundmass of this basalt is composed of plagioclase microlites with tiny interstitial clinopyroxenes. Vesicles are infilled with chlorite and quartz. The few larger plagioclase phenocrysts have been partially altered to calcite.
A granitic inequigranular diorite with graphically intergrown, sericitized k-feldspar and quartz, and chloritized hornblende. Clinozoisite and sphene are accessory minerals found throughout the thin section.
Hypidiomorphic, inequigranular clinopyroxene with serpentine-filled fractures and interstices.