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USGS1976

The aeromagnetic expression of bedrock geology between the Clinton-Newbury and Bloody Bluff fault zones, northeastern Massachusetts

The pattern of mapped bedrock geology in northeastern Massachusetts bears a striking similarity to patterns of aeromagnetic anomalies in the area. The correspondence of the geology with the anomaly pattern and lineaments on aeromagnetic maps is especially well shown northwest of Boston between the Clinton-Newbury and Bloody Bluff fault zones. Here, an aluminous schist unit and an underlying series of metasedimentary and metavolcanic rocks south of the Clinton-Newbury fault zone coincide with a zone of northeast-trending positive anomalies that contrast with the broad magnetic low north of the fault. Nearly concordant granitic bodies intrude the metamorphic series and correspond to broad magnetic lows between the fault zones. Smaller narrower lows correspond to zones of amphibolite-carbonate rock. Commonly faults are indicated by lineaments that separate areas of different magnetic pattern and that offset or terminate other lineaments. The northeast-trending Spencer Brook and Assabet River fault zones and other unnamed faults are emphasized by magnetic lineaments trending slightly east of the strike of the stratigraphy.

Massachusetts↗

USGS1975

Paleotectonic investigations of the Pennsylvanian System in the United States, Part I: Introduction and regional analyses of the Pennsylvanian System

The Pennsylvanian is the fourth geologic system to be analyzed and synthesized by geologists of the U.S. Geological Survey in the form of a paleotectonic study covering the conterminous United States. Earlier investigations were of the Jurassic, Triassic, and Permian Systems. Results were published as Miscellaneous Geologic Investigation Maps I-175, I-300, and I-450 and in Professional Paper 515. The objective of these investigations is to provide in graphic form the factual basis for recognition of tectonic events of each system on a countrywide scale. The maps in this publication depict rock thickness, generalized lithology, ancient geography, and other regional relations of the Pennsylvanian System. Method of preparation of the maps, the stratigraphic limits of the map units, and various stratigraphic and structural features and their probable tectonic significance are discussed. Pennsylvanian data were largely compiled between 1961 and 196 by 16 geologists, including the late Harold R. Wanless, who covered the five eastern regions and contributed to several of the special studies. The areas of responsibility of the cooperating geologists are indicated in figure 1. Work in Kansas was done by Gary F. Stewart, of the Kansas Geological Survey. Results of this investigation are presented in three units. Part I comprises an introduction and 17 chapters, each describing and discussing one of the regions in which the conterminous United States was divided for purposes of study and mapping. Part II is a synthesis of Pennsylvanian history to accompany interpretive maps of the five divisions of the Pennsylvanian System treated in this publication; it also includes a series of chapters on depositional environments, climatic conditions, and economic products of the system. The final section of part II is devoted to an index of localities and sources used in construction of the principal maps of this publication. Part III consists of the plates on which are presented the major maps and sections.

Professional Paper↗

USGS1970

Uraninite-bearing contact metamorphic deposits, Heaths Peak, Carbon County, Wyoming

Deposits that contain uraninite and sulfide minerals at Heaths Peak, Carbon County, Wyo., display a zoned distribution of metals from the edge of granite into adjacent metamorphic rocks. The metallic minerals -- uraninite, molybdenite, pyrite, chalcopyrite, galena, pyrrhotite, and marcasite -- are concentrated on the undersides of metamorphosed roof pendants. At the Little Man mine, deposition was related to a small cupola projecting into the central part of an elongate pendant. The host rocks and the deposits are of Precambrian age.

Wyoming↗