Browse Items (17 total)

  • Collection: (DUCO) Barrovian Metamorphic Sequence -- Dutchess County, New York

DOC043008.pdf
OCR PDF of supplemental information for the Barrovian Metamorphic Sequence--Dutchess County, NY

DUCO-16 hand sample of marble
Metamorphised Balmville limestone with visible phlogopite crystals. Also contains tremolite visible at the outcrop level. Within nose of anticline of Walloomsac schist.

The PPL thin section shows a large irregular calcite grain with tremolite at…

DUCO-15 hand sample of marble
Metamorphised Balmville limestone with visible phlogopite crystals. Also contains actinolite.

Thin section shows calcite with interspersed pleochroic phlogopite.

DUCO-14 hand sample of marble
Metamorphised Briarcliff dolostone with visible micas. Contains diopside, tremollite, and phlogopite. At the metamorphic grade of the first sillimanite isograd.

Thin section shows irregular dolomite grains in the center, with pleochroic…

DUCO-13 hand sample of marble
Metamorphised Briarcliff dolostone.

The thin section shows well-twinned dolomite grains with diopside at the bottom.

DUCO-12 hand sample of muscovite schist
Extremely coarse-grained muscovite schist. Large garnets visible in hand sample. Sillimanite is not recognizable in hand sample, however.

The thin section shows muscovite (with minor sillimanite) in a large band, biotite, staurolite, and…

DUCO-11 hand sample of kyanite biotite garnet schist
Schist with coarse biotite controlling foliation. Garnets visible in some hand samples. Kyanite blades without preferred orientation--at higher concentration within folds. Possibly from the Walloomsac schist.

The PPL thin section shows biotite,…

DUCO-10 hand sample of quartzite
Metamorphised sandstone with a gray, glassy appearance. From the Paughquag quartzite, a late Cambrian formation. The basal Cambrian quartzite rests on pre-Cambrian gneisses.

The thin section shows quartz and plag with some biotite and grain…

DUCO-9 hand sample of staurolite schist
Schist with coarse staurolite grains. This outcropping is approximately on the strike of the chloritoid schists (sample 7). Also contains garnet, muscovite, feldspar, and quartz. Presumed to be from the Everett Schist.

The thin section shows…

DUCO-8 hand sample of staurolite chloritoid schist
Schist bearing both staurolite and chloritoid. This marks the first appearance of staurolite in the metamorphic sequence. Also contains garnet, muscovite, chlorite, biotite, feldspar, and quartz. The assemblage in not in equilibrium.

The thin…

DUCO-7 hand sample of chloritoid schist
Schist with coarse chloritoid crystals (up to 1/8 inch) without preferred orientation. These crystals grow across the foliation developed in the schist, but appear deformed. Chloritoid is a silicate mineral made in metamorphism. It also contains…

DUCO-6 hand sample of garnet biotite schist
Schist with sparse garnet. This schist is darker and graphitic. It also contains biotite, chlorite, muscovite, feldspar, and quartz.

The thin section shows several large biotite grains with an included garnet, small quartz grains, muscovite, and…

DUCO-5 hand sample of graphitic slate
A highly graphitic slate in the Walloomsac slates. Contains pyrite. This rock also contains biotite, chlorite, muscovite, quartz, ilmenite, and pyrite.

The thin section shows large biotite grains, and chlorite muscovite, and quartz. Fluid…

DUCO-4 hand sample of kink fold in slate
Kink fold in a slate from the Mt. Merino Member.

This rock is from the chlorite zone of the Barrovian metamorphic sequence (low metamorphism).

DUCO-3 hand sample of graywacke
The graywacke facies in the Mt. Merino member (where sample 4 also comes from). Graywacke is a hard, dark-colored sandstone. This sandstone represents a similar rock to the protolith for the quartzite of sample 10.

The thin section shows quartz,…

DUCO-2 hand sample of green shale
Green shale of the Indian River member of the Normanskill formation. This shale contains muscovite, chlorite, plagioclase, and quartz.

The thin section shows quartz and biotite with some minor opaques.

This rock is from the chlorite zone of the…

xpl / ppl
Red shale from the Indian River member of the Normanskill formation. This rock contains hematite, chlorite, muscovite, plagioclase, and quartz.

The thin section shows muscovite and biotite with some larger quartz grains visible and minor hematite…