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Geologists and geophysicists study the earth’s crust (the lithosphere, the brittle zone) and the asthenosphere (the ductile zone where rock moves like warm taffy). The movement of the lithosphere is studied in plate tectonics with the theory that the lithosphere is a mosaic of about twenty tectonic plates.
The tectonic plates five distinct landscape provinces in Georgia. They are the 1) Coastal Plain southern Georgia), 2) Piedmont (which means foothills, north to Stone Mountain), 3) Blue Ridge, 4) Valley and Ridge, and 5) Appalachian Plateau.
As reported in Wikipedia “Ore Genesis: Plate tectonics is the underlying mechanism for generating gold deposits. The majority of primary gold deposits fall into two main categories: lode gold deposits or intrusion-related deposits.
Lode gold deposits are generally high-grade, thin, vein and fault hosted. They are primarily made up of quartz veins also known as lodes or reefs, which contain either native gold or gold sulfides and tellurides. Lode gold deposits are usually hosted in basalt or in sediments known as turbidite, although when in faults, they may occupy intrusive igneous rocks such as granite.
Lode-gold deposits are intimately associated with orogeny and other plate collision events within geologic history. Most lode gold deposits sourced from metamorphic rocks because it is thought that the majority are formed by dehydration of basalt during metamorphism. The gold is transported up faults by hydrothermal waters and deposited when the water cools too much to retain gold in solution.
Intrusive related gold (Lang & Baker, 2001) is generally hosted in granites, porphyry or rarely dikes. Intrusive related gold usually also contains copper, and is often associated with tin and tungsten, and rarely molybdenum, antimony and uranium. Intrusive-related gold deposits rely on gold existing in the fluids associated with the magma (White, 2001), and the inevitable discharge of these hydrothermal fluids into the wall-rocks (Lowenstern, 2001). Skarn deposits are another manifestation of intrusive-related deposits.
Placer deposits are sourced from pre-existing gold deposits and are secondary deposits. Placer deposits are formed by alluvial processes within rivers, streams and on beaches. Placer gold deposits form via gravity, with the density of gold causing it to sink into trap sites within the river bed, or where water velocity drops, such as bends in rivers and behind boulders. Often placer deposits are found within sedimentary rocks and can be billions of years old, for instance the Witwatersrand deposits in South Africa. Sedimentary placer deposits are known as 'leads' or 'deep leads'.
Placer deposits are often worked by fossicking, and panning for gold is a popular pastime.
Laterite gold deposits are formed from pre-existing gold deposits (including some placer deposits) during prolonged weathering of the bedrock. Gold is deposited within iron oxides in the weathered rock or regolith, and may be further enriched by reworking by erosion. Some
laterite deposits are formed by wind erosion of the bedrock leaving a residuum of native gold metal at surface.
A bacterium, Cupriavidus metallidurans plays a vital role in the formation of gold nuggets, by precipitating metallic gold from a solution of gold (III) tetrachloride, a compound highly toxic to most other microorganisms.[3] Similarly, Delftia acidovorans can form gold nuggets.[4]”
As placier gold was washed by erosion into streams it was located by early settlers in Georgia. Ben Parks, a deer hunter tripped on a rock laden with gold in1827. After easy pickings miners had to locate gold by panning. This created the first gold rush in the United States. It caused the native peoples (Cherokee) to be uprooted from their homeland known as the Trail of Tears. Dahlonega Georgia had the first U.S. mint.
The tectonic plates five distinct landscape provinces in Georgia. They are the 1) Coastal Plain southern Georgia), 2) Piedmont (which means foothills, north to Stone Mountain), 3) Blue Ridge, 4) Valley and Ridge, and 5) Appalachian Plateau.
As placier gold was washed by erosion into streams it was located by early settlers in Georgia by panning. This created the first gold rush in the United States. It caused the native peoples (Cherokee) to be uprooted from their homeland known as the Trail of Tears. Dahlonega Georgia had the first U.S. mint even though the Cherokee Nation in 1825 had documented that any gold,silver, or copper mines within the boundaries of the Cherokee Nation would be Cherokee property.
REFERENCES:
Roadside Geology of Georgia, Gore and Witherspoon.
An Introductory Report, John C Calhoun Gold Mine, Sherry Boatwright, 1974 _
Nearby geocaches related to Georgia Gold:
GC2T11E (mystery) Dahlonega Gold Museum (admission fee, part of Georgia Parks Geo series).
GC427NB (multi-cache) Dahlonega Gold Divers
GC5G8GA (Traditional) 4th Looking for Gold(/p>
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1. The ductile zone is known as the ______________________ 2. How many tetonic plates form the lithosphere? 3. Placer deposits are formed by what process? 4. Describe the mining equipment at the end of the underground tour. Pictures are optional but are WELCOMED 5. (Optional) What creatures visit in winter Congrats to CO-FTF Cache Yoo and Wolfling70
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