ABSTRACT

The Flint Creek Range of west-central Montana is a tectonically and economically important component of the Montana fold-and-thrust belt. The structural development of the range was controlled by several tectonic elements within a complex orogenic setting, producing "typical" fold-and thrust structures in an "atypical" relationship. The major tectonic elements include the Boulder batholith and the block-faulted Deer Lodge Valley to the east, the Montana lineament to the north, the Sapphire tectonic block to the west, and the Philipsburg batholith and its related stocks to the south.

The northern Flint Creek Range exhibits two major structural styles which serve to subdivide the area into two structural provinces.

The eastern province exhibits three major, north-south trending, anticlines with westward vergence. These folds are overturned to the west and plunge north toward the Montana lineament. Several high angle faults of great lateral extent offset the western flanks of these folds. The eastern part of this area contains diorite sills that are folded with the Phanerozoic sedimentary rocks. The southeastern border of the eastern province is typified by granodiorite intrusions and minor thrust faults with east dipping axial planes.

The western province is characterized by asymmetric folds exhibiting eastward vergence. West dipping thrust faults dominate the structural style and are accompanied by several overturned, north plunging anticlines Two klippes of western province rocks overlie eastern province structures. The southern part of this area is marked by several granodiorite intrusions.

The economic potential of the northern Flint Creek Range includes ore deposits of gold, silver, lead, zinc, manganese, phosphate, and possibly oil and gas in structurally deformed Phanerozoic rocks.