Mid-Atlantic Iron Belt Project - Phase 1 - Rittenhouse Gap Characterization

Kurt Friehauf - Kutztown University

Rittenhouse Gap - phase 1One undergraduate student involved:
Project:  Student systematically sampled rocks from old mine pits for study in the lab.  Rock samples were cut and prepared for microscopic study both by student and professional thin section maker.  Student created database for managing large sample suite.  Surveyed outline of mine pits to constrain sample location.  Special stain used to characterize chemical composition of minerals in cut rock slabs.

Rittenhouse Gap - phase 1Results: Maps of the locations of old mine pits and rock samples provide the context for all subsequent studies on the project.  Iron veins are related to development of sodium-rich alteration of host rock granites and gneiss.  There is no evidence for basaltic magmas being present during iron deposition.  Quartz, biotite mica, muscovite, and blue alkali amphibole are the minerals most closely associated with iron deposition.  Iron deposits appear partially deformed by shearing and metamorphism.  Iron deposits crosscut by rhyolite dike that chemically resembles 700 million year old felsic dikes elsewhere in the eastern U.S. (Robert C. Smith, II, pers. comm., 2002).  Pyrite, molybdenite, and fluorite-bearing veinlets with trace sphalerite cut rhyolite dikes in the field area and so must represent a separate, younger mineralization event.  The association of iron minerals are associated with sodium-rich silicate minerals, suggests these deposits may be more similar to the iron deposits in Chile formed by leaching brines rather than to granite-related iron deposits.

Rittenhouse Gap - phase 1 Because we now have a good understanding of the geology of the Rittenhouse area, several different Kutztown University geology classes now use the area as a fieldtrip stop for classic Precambrian (i.e., very old) rocks in Pennsylvania.

This project was featured in the Kutztown University Magazine.

Rittenhouse Gap - phase 1Presentation: Orner, Richard, and Friehauf, Kurt C., 2000, Geology of the Rittenhouse Gap Iron District, Berks County, Pennsylvania [abs]: Geological Society America Abstracts with Programs, v. 32, p. A83.  (Rich traveled and presented this work with me at the Geological Society America national meeting in Reno, Nevada)

on to Phase 2 - Rittenhouse Geophysical Reconn.

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