Browsing by Subject "gravity"

Now showing 1 - 5 of 5
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    GEOPHYSICAL AND PETROLOGIC ADVANCES IN UNDERSTANDING THE TAUNTON-BELT WEDGE, AN ARCHEAN TERRANE WITHIN THE MINNESOTA RIVER VALLEY SUBPROVINCE OF THE SUPERIOR CRATON, NORTH-CENTRAL U.S.A.
    (2023) Southwick, David L; Chandler, V.W.; Jirsa, Mark A; Boerboom, Terrence J
    The Taunton-belt wedge, defined herein, is an unexposed fault-bounded Archean terrane located within the Morton block of the Minnesota River Valley (MRV) subprovince of the Superior Craton. It is bounded on the north by the Yellow Medicine shear zone (YMSZ), a prominent regional structure that extends from the west margin of the Paleoproterozoic Penokean orogen in Minnesota to the east margin of the Paleoproterozoic Trans-Hudson orogen in South Dakota. The south boundary of the wedge is a less distinct curving fault zone that splays west–southwest from the YMSZ in south-central Minnesota and rejoins it in eastern South Dakota. The interior geology of the wedge is poorly known, owing to continuous cover of the Precambrian basement by Phanerozoic strata and Pleistocene glacial deposits. Regional aeromagnetic and ground gravity mapping indicate a broad belt of mafic metavolcanic and related rocks in roughly the northern half of the wedge, and many granitoid intrusions in the southern half. Geophysical signatures characteristic of layered gneiss, such as those observed over known gneiss elsewhere in the Morton block, are minor to absent.
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    Gravity and Magnetic Studies in Carver County and Adjacent Areas, Southeastern Minnesota
    (Minnesota Geological Survey, 2009) Chandler, V.W.
    This report summarizes the gravity and magnetic studies that were done as part of the Carver County Geologic Atlas (CGA) study. This work compliments the bedrock geology component of the project, and it has three objectives, as described below: 1. The first objective is to create gravity and magnetic grid images to assist in compiling the bedrock map sheet for the CGA. 2. The second objective was to use gravity and magnetic model studies to help create geologic cross sections that are to accompany the bedrock geology map sheet. 3. The third objective was to apply a semi-automated magnetic interpretation scheme called Euler Deconvolution (Reid and others, 1990), which estimates the location and depth of magnetic anomaly sources.
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    M-121 Geologic map of pre-Cretaceous bedrock in southwest Minnesota
    (Minnesota Geological Survey, 2002) Southwick, D.L.
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    M-132 Maps of bedrock geology and superimposed magnetic on gravity (SMOG) anomaly for East-central Minnesota
    (Minnesota Geological Survey, 2003) Jirsa, M.A.; Chandler, V.W.; Lively, R.S.; Boerboom, T.J.
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    Upgrade of the Gravity Database
    (2011) Chandler, V.W.; Lively, R.S.
    The principal fact gravity database in Minnesota is comprised of over 59,000 measurements collected since 1950. It contains point location data, elevations, free-air and Bouguer anomaly values, field information and base U.S.G.S. quadrangle locations. Over the years gravity data in Minnesota has proven to be a useful resource for the Minnesota Geological Survey (MGS) in its mission of bedrock mapping, and it has provided mineral exploration companies with a significant supplement to exploration programs in Minnesota. Because much of the Precambrian bedrock in Minnesota lies beneath thick glacial deposits, gravity measurements, which are sensitive to density variations, are particularly helpful at inferring structures and rock types deep in the subsurface. The state-wide gravity data is most commonly used in conjunction with the high- resolution aeromagnetic data from Minnesota, which is highly sensitive to magnetic variations in the underlying Precambrian rocks.In 2003, the MGS released a state-wide gravity database with 57890 stations (gravity meter readings). This is an update to that database.