Geology and Discovery History of the Money Knob Gold Deposit, Tolovana Mining District, Eastern Alaska

Author(s):  
Jeffrey Pontius ◽  
Russell Myers ◽  
Chris Puchner
1993 ◽  
Vol 30 (4) ◽  
pp. 764-768 ◽  
Author(s):  
John M. Murphy ◽  
Arne Bakke

Eight apatite and two zircon fission-track ages provide evidence of complex Tertiary thermal overprinting by hydrothermal fluids in the Gilmore Dome area. Five ages on apatite from the Fort Knox gold deposit average 41 Ma, one from the Stepovich prospect is 80 Ma, and two from Pedro Dome average 67 Ma. Elevations of these samples overlap but their ages do not, indicating that each area experienced a different thermal history.Ages of apatite from the Fort Knox gold deposit decrease with elevation from 42 to 36 Ma but have data trends indicative of complex cooling. Two ~51 Ma ages on zircon indicate that maximum temperatures approached or exceeded ~180 °C. An alteration assemblage of chalcedony + zeolite + calcite + clay in the deposit resulted from deposition by a paleo-hydrothermal system. The data suggest that the system followed a complex cooling path from > 180 to < 110 °C between 51 and 36 Ma, and that final cooling to below 60 °C occurred after ~25 Ma.The 80 Ma age from Stepovich prospect either resulted from cooling after intrusion of the underlying pluton (~90 Ma) or records postintrusion thermal overprinting sometime after ~50 Ma. The 67 Ma samples from Pedro Dome may also have experienced partial age reduction during later heating. The differences in the data from the different areas and the presence of a late alteration assemblage at Fort Knox suggest that the fluids responsible for heating were largely confined to the highly fractured and porous Fort Knox pluton.


2021 ◽  
pp. 1-17
Author(s):  
Behnam Shafiei Bafti ◽  
István Dunkl ◽  
Saeed Madanipour

Abstract The recently developed fluorite (U–Th)/He thermochronology (FHe) technique was applied to date fluorite mineralization and elucidate the exhumation history of the Mazandaran Fluorspar Mining District (MFMD) located in the east Central Alborz Mountains, Iran. A total of 32 fluorite single-crystal samples from four Middle Triassic carbonate-hosted fluorite deposits were dated. The presented FHe ages range between c. 85 Ma (age of fluorite mineralization) and c. 20 Ma (erosional cooling during the exhumation of the Alborz Mountains). The Late Cretaceous FHe ages (i.e. 84.5 ± 3.6, 78.8 ± 4.4 and 72.3 ± 3.5 Ma) are interpreted as the age of mineralization and confirm an epigenetic origin for ore mineralization in the MFMD, likely a result of prolonged hydrothermal circulation of basinal brines through potential source rocks. Most FHe ages scatter around the Eocene Epoch (55.4 ± 3.9 to 33.1 ± 1.7 Ma), recording an important cooling event after heating by regional magmatism in an extensional tectonic regime. Cooling of the heated fluorites, as a result of thermal relaxation in response to geothermal gradient re-equilibration after the end of magmatism, or exhumation cooling during extensional tectonics characterized by lower amount of erosion are most probably the causes of the recorded Eocene FHe cooling ages. Oligocene–Miocene FHe ages (i.e. 27.6 ± 1.4 to 19.5 ± 1.1 Ma) are related to the accelerated uplift of the whole Alborz Mountains, possibly as a result of the initial collision between the Afro-Arabian and Eurasian plates further to the south.


2016 ◽  
Vol 113 ◽  
pp. 73-87 ◽  
Author(s):  
Quentin Masurel ◽  
John Miller ◽  
Kim A.A. Hein ◽  
Eric Hanssen ◽  
Nicolas Thébaud ◽  
...  

2002 ◽  
Vol 712 ◽  
Author(s):  
W. Fasnacht ◽  
J.P. Northover

ABSTRACTFinds of metallic copper from various primary smelting sites in the Sia valley in Cyprus have been analysed by ICP-OES for their composition and by optical and electron microscopy for metallography. Results show a characteristic pattern of impurities for each of the sites examined which allow an assignment to specific types of ore body and geological matrix. Different zones of the Cyprus Ophiolite Complex were exploited in different periods in antiquity, but these results show different types could be exploited contemporaneously within a specific period, especially during the first millennium BC. One location in this area, Agia Varvara-Almyras, an Iron Age copper smelting site with the only complete chain of operation recorded in ancient Cypriote metallurgy, is used to show how analytical work can guide future field surveys to find ancient furnaces, slag heaps and mines. The ultimate goal of the project is to extend it to reconstruct the complete history of copper production in a well-defined mining district over the last 4000 years.


2020 ◽  
Vol 1 (1) ◽  
pp. 211-227
Author(s):  
N.A. Denisova ◽  
◽  
R.K. Khayryatdinov ◽  

2013 ◽  
Vol 45 ◽  
pp. 235-249 ◽  
Author(s):  
Luis C. Mantilla Figueroa ◽  
Thomas Bissig ◽  
Víctor Valencia ◽  
Craig J.R. Hart

2003 ◽  
Vol 40 (3) ◽  
pp. 395-430 ◽  
Author(s):  
T L Muir

A complex history of volcano-sedimentary deposition, polyphase strain, multiple intrusive events, and various stages of porphyroblastesis is indicated for the Hemlo gold deposit area within the Hemlo greenstone belt. Structural elements can be assigned to at least six stages of development (D1–D6). D1 generated small-scale folds and low-angle faults (thrusts?) with no planar fabric, except within strain aureoles around the earliest intrusions. D2 was a progressive event resulting from northeast-directed compression, which generated regional, predominantly S-shaped folds (early D2); penetrative planar and linear fabrics, overturned stratigraphy, and formation of an inflection in the strike of the greenstone belt (mid-D2); and development of high-strain zones with dominant sinistral and local dextral shear sense (late D2). D3 was a distinctly separate progressive event resulting from northwest-directed transpression, which generated variably penetrative east- to northeast-striking foliation (S3), ductile dextral shear fabrics, and small-scale Z-shaped folds (early D3), followed by brittle–ductile to brittle development of cataclasite and pseudotachylite in layer-parallel zones (late D3). D4 resulted in contractional kinks and brittle fractures, locally in conjugate sets. D5 and D6 are represented by brittle to brittle–ductile faults, which overprint Paleoproterozoic and Mesoproterozoic dikes, respectively. Four granitoid magmatic events span the interval 2720–2677 Ma, with emplacement mainly during D2, between ca. 2690 and ca. 2684 Ma. A protracted period of regional medium-grade metamorphism likely spanned the D2–D3 stages. The Hemlo gold deposit was emplaced during mid-D2 and was largely controlled by D2 structural elements and competency contrast between rock units.


2021 ◽  
Vol 72 (3) ◽  
pp. 99-106
Author(s):  
Mikhail V. Druzin ◽  

The article explores the history of ownership of the Lysvensky mining district in the Perm province by Peter Pavlovich (1819–1900) and Pavel Petrovich (1847–1902) Shuvalov through the prism of the owner’s personal attitude to the family factories and his involvement in the management process. Despite the fact that there is a continuity of two generations in some external signs of ownership (recourse to the management of factories prior to the legal entry into ownership rights, change of local administration by a new owner, desire to transfer the mining estate to the sole full ownership), they are in many ways opposite to each other due to the subjective circumstances and personal qualities of the owners. Peter Pavlovich represents the type of an “old owner” who is only ready to receive income from his estates, without being interested in the real state of affairs and the management quality. His son, Pavel Petrovich, became the personification of a “new type” owner, who invests his personal time, effort and energy in the development of his own “business”. But, the return of the heirs after his sudden death to the former attitude to the “business” led to the fact that they failed to keep the Lysvensky district as a part of the ancestral property, allowing its corporatization with the participation of bank capital.


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