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24 hits

  • Thumbnail for SYH-1F
    SYH-1F

    A contact between blueshist and an omphacite boudin is captured in this thin section. The blueschist side is strongly foliated due to aligned glaucophane with interspersed sphene and minor muscovite and chlorite. The contact itself is an aggregate of sphene with interstitial chlorite and clinozoisite. Omphacite is the dominant mineral on the other side of the contact, though some glaucophane, muscovite, sphene, and clinozoisite is present. Quartz rims surround reddish opaques.

  • Thumbnail for SYH-3D-1
    SYH-3D-1

    This thin section consists of several zones. The first, a fine-grained glaucophane schist with accessory sphene and zoisite. Microcrenulations cause the boundaries between individual glaucophane crystals to blur. This zone is abruptly cut by a green, omphacite-rich band. In the third zone, the glaucophane fabric is interleaved with elongate aggregates of omphacite and other accessory minerals.

  • Thumbnail for SYH-1GG
    SYH-1GG

    The fabric in this thin section is more disordered than others from this suite. All phases commingle and an alignment of elongate phases amidst many equant phase forms a weak foliation. Garnet and omphacite form porphryclastic, poikiloblastic grains.

  • Thumbnail for SYH-1II
    SYH-1II

    Like the other blueschists, aligned glaucophane, clinozoisite, and sphene define the foliation, however, this sample lacks omphacite and garnet, and contains quartz and aragonite instead. These latter two phases are interstitial and occur in minor amounts,

  • Thumbnail for SYH-1BB
    SYH-1BB

    Fine-grained glaucophane, the primary constituent of this blueschist, is aligned to form a foliation. Sphene is visible to the at the macroscopic scale and ranges in grain shape from euhedral diamonds to skeletal masses. Sphene twinning is evident.

  • Thumbnail for SYH-1FF
    SYH-1FF

    This blueschist consists mostly of aligned glaucophane, micas, and sphene. Occasional inclusion-rich porphyroclasts of nephaline are observed.

  • Thumbnail for GR-07
    GR-07

    Aligned muscovite crystals form a foliation with anhedral, interlobate, though elongated grains of quartz and k-feldspar. Grain boundaries are irregularly shaped.

  • Thumbnail for SS-4
    SS-4

    Randomly oriented biotite phenocrysts dominate this thin section. The interstices between phenocrysts contain prisms of k-feldspar, anhedral masses of calcite and nephaline, and radial splays of muscovite. Opaques are equant and up to 0.5mm in diameter. The nephaline phase has a bluish cast in cross-polarized light. The groundmass phases are cross-cut by a mesh-work of clays and various alteration products. Slightly diamond-shaped rutile is pervasive throughout.

  • Thumbnail for BB9
    BB9

    This medium-grained allotriomorphic diorite is dominated by plagioclase, much of which is concentrically zoned and larger in size than most other phases in the sample. Clusters of the ferromagnesian phases appear to be pseudomorphing a previous, rectangular, phenocrystic phase.

  • Thumbnail for SYH-1CC
    SYH-1CC

    The foliation in this thin section, defined primarily by aligned glaucophane and clinozoisite, as well as strings of euhedral and aggregated sphene, wraps around larger, equant omphacite and glaucophane grains. The grain size is larger than many others in this suite and the foliation weaker.

  • Thumbnail for SYH-1DD
    SYH-1DD

    Glaucophane, muscovite, sphene, and elongate aggregates of epidote-group minerals define the foliation in this thin section. Poikiloblastic garnet and omphacite grains contain inclusions which include glaucophane and rutile.

  • Thumbnail for 671
    671

    This allotriomorphic granite shows evidence of weathering as most feldspars are partially obscured by a dusting of clay minerals. Tartan twinning of microcline is obvious throughout the sample. The curving of biotite cleavage and subhedral grain shapes indicates the biotite is not pristine. It is commonly found occurring with subhedral hornblende as well as large, clear to light brown, anhedral sphene crystals.

  • Thumbnail for PS-2a-pgr
    PS-2a-pgr

    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.

  • Thumbnail for SYH-1D-2
    SYH-1D-2

    Glaucophane, muscovite, sphene, and elongate aggregates of epidote-group minerals define the foliation in this thin section. Poikiloblastic garnet and omphacite grains contain inclusions which include glaucophane and rutile and the host minerals show resorption textures.

  • Thumbnail for 0620-1B
    0620-1B

    Strongly aligned, microcrenulated glaucophane is the primary constituent of this blueschist. Sphene and muscovite are much less abundant.

  • Thumbnail for SYH-20
    SYH-20

    This paragonite schist is peppered with euhedral and aggregated clinozoisite. A few phengitic pods with large zoisite grains are found.

  • Thumbnail for SYH-1E
    SYH-1E

    Glaucophane, muscovite, sphene, and elongate aggregates of epidote-group minerals define the foliation in this thin section. Poikiloblastic garnet and omphacite grains contain inclusions which include glaucophane and rutile.

  • Thumbnail for BB8
    BB8

    Large k-feldspar and quartz crystals provide a backdrop for the smaller, less well-preserved mafic phases in this sample. Decomposing biotite is frequently found interfingered with chlorite. Hornblende grains are rather skeletal. Plagioclase crystals have relatively rounded corners and tend to cluster together. Large anhedral aggregates of sphene are interspersed in the interstices between k-feldspar grains.

  • Thumbnail for PS-2a-qd
    PS-2a-qd

    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.

  • Thumbnail for SYH-1EE
    SYH-1EE

    Allotriomorphic omphacite and clinozoisite are intergrown with one another, with clinozoisite occurring frequently as inclusions within the omphacite crystals. The occurrence of muscovite is typically contained to polycrystalline nodes with radiating crystals. The conspicuous rutile grain in the center with radiating veinlets has a rim of plagioclase buffering it from the surrounding material. It contains inclusions of chlorite and sphene. Sphene is abundant as large, subhedral clasts.

  • Thumbnail for SYH-3D-2
    SYH-3D-2

    This thin section consists of several zones. The first, a fine-grained glaucophane schist. The boundaries between individual glaucophane crystals frequently blur. Aggregates of sphene are stretched out lines paralleling the complexly folded foliation. This zone is abruptly cut by a green, omphacite-rich band, bordered on each sided by a greater concentration of sphene. In the third zone, the glaucophane fabric is interleaved with elongate aggregates of omphacite, epidote and sphene.

  • Thumbnail for SYH-1R
    SYH-1R

    Aligned, elongate, millimetric-scale actinolite crystals dominate this thin section. Layers of actinolite crystals are interleaved with layers of chlorite. Basal sections of actinolite, which show fabulous amphibole cleavage are strongly plucked, leaving patchy void spaces throughout the thin section.

  • Thumbnail for SYH-1HH
    SYH-1HH

    Strongly aligned, microcrenulated glaucophane and muscovite define the tightly folded foliation of this rock. Sphene is skeletal with inclusions of both aforementioned phases.

  • Thumbnail for 0621-4
    0621-4

    This fine grained sample is fairly monomineralic. The small, feathery crystals are aligned to form a weak foliation. Opaques are plentiful though sphene much less so.