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Gouverneur Marble (Mesoproterozoic, ~1.1 Ga; Route 11 roadcut north of Antwerp, New York State, USA) 38 | by James St. John
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Gouverneur Marble (Mesoproterozoic, ~1.1 Ga; Route 11 roadcut north of Antwerp, New York State, USA) 38

Marble in the Precambrian of New York State, USA.

 

Marble is a crystalline-textured metamorphic rock composed of calcite (CaCO3 - calcium carbonate). It bubbles in acid and does not scratch glass. Marble forms by the metamorphism of limestone, a common biogenic sedimentary rock.

 

The outcrop seen here is composed of whitish marble (mosty banded) that is graphitic and phlogopitic. Some incorporated calc-silicate rock clasts having reaction rims are present. A portion of the outcrop consists of dolomitized marble (not dolomitic marble), where the host marble was locally dolomitized by injection of hot, magnesium-bearing fluids along a fracture. This resulted in the formation of a dike-like zone of light brown dolomitized marble, but it's not a dike.

 

The rocks here are part of the Gouverneur Marble of New York State's Adirondack Lowlands. The original limestones were metamorphosed at about 1.1 billion years ago, during the Grenville Orogeny.

 

The banding is striking at this spot on the outcrop - it possibly represents original limestone bedding.

 

Stratigraphy: Gouverneur Marble, Oswegatchie Group, Mesoproterozoic, ~1.1 Ga metamorphic age

 

Locality: Antwerp North Outcrop - roadcut on the southeastern side of Route 11, north of the town of Antwerp, Adirondack Lowlands, northern New York State, USA (44° 14’ 05.50” North latitude, 75° 36’ 01.83” West longitude)

 

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Taken on May 11, 2012