Physical Sciences and Mathematics Commons^™

Structural Analysis And Interpretation Of Deformation Along The Keweenaw Fault System From Lake Linden To Mohawk, Michigan, Nolan G. Gamet

Dissertations, Master's Theses and Master's Reports

The Keweenaw fault is likely the most significant and most studied fault associated with the Midcontinent Rift System. The fault roughly bisects the Keweenaw Peninsula and places Portage Lake Volcanics (~1.1 Ga) over much younger Jacobsville Sandstone (~1.0 Ga). Published bedrock geology maps with cross sections from the 1950s show the fault as a single continuous trace that is locally associated with smaller cross faults and splays. The accompanying cross-sections show hanging-wall volcanic strata having a well-defined, listric geometry with dip decreasing away from the fault to the northwest.

This M.S. thesis presents a structural analysis and interpretation of the …

Structural Analysis And Slip Kinematics Of The Keweenaw Fault System Between Bête Grise Bay And Gratiot Lake, Keweenaw County, Michigan, Daniel J. Lizzadro-Mcpherson

Dissertations, Master's Theses and Master's Reports

The Keweenaw fault is perhaps the most significant geologic structure on the Keweenaw Peninsula, with an estimated 7-11 km of reverse slip juxtaposing volcanic strata of the ~1.1 Ga Portage Lake Volcanics above ~1.0 Ga Jacobsville Sandstone. The fault has been interpreted as a rift-bounding normal fault later inverted by compressional pulses of the Grenville Orogeny or, more recently, as part of a detached thrust fault system unrelated to an earlier normal fault. The fault is shown on published maps as a single continuous fault trace whose sinuosity implies multiple fault segments and complex slip dynamics. Mapping along Bête Grise …

Fluid Inclusion Study Of Selected Calcite Associated With Native Copper, Quincy Mine, Keweenaw Peninsula, Michigan, David Kelly

Dissertations, Master's Theses and Master's Reports

The Keweenaw Peninsula is famous for hosting the largest accumulation of native copper anywhere in the world. Previous studies have looked for the fluids responsible for creating the native copper deposits but were unable to conclusively demonstrate that fluid inclusions can provide valuable insight into the hydrothermal/metamorphogenic fluids responsible for these unique deposits.

This report focused on fluid inclusions from calcite precipitated during the native copper mineralizing event. Calcite crystals with inclusions of native copper growing into vugs from a single location, the Quincy Mine, were hypothesized to have a higher chance to be undisturbed by seismic events that would …

Paleomagnetic Investigation Of Igneous Rocks Deformed By The Keweenaw Fault In The Northwestern Keweenaw Peninsula., Daniel Trekas

Dissertations, Master's Theses and Master's Reports

One of the most prominent structural features associated with the ~1.1 Ga Midcontinent Rift (MCR) system is the >350 km long Keweenaw Fault that bisects the Keweenaw Peninsula, separating the MCR-related Portage Lake Volcanics (PLV) and the younger Jacobsville Sandstone (JS). The fault trend is NE-NNE over most of its length, but changes to an easterly direction along the shore of Bête Grise Bay near the end of the peninsula. Conventionally, the Keweenaw Fault has been considered to be a continuous reverse (dip-slip) fault formed by inversion of an original rift-bounding normal fault during the Grenville Orogeny. However, recent mapping …