THE AGE OF MONAZITE AT THE GARNET ISOGRAD IN THE CENTRAL APPALACHIAN PIEDMONT OF PENNSYLVANIA: FURTHER EVIDENCE IN SUPPORT OF AN INVERTED METAMORPHIC GRADIENT BELOW THE EMBREEVILLE THRUST

2019 ◽  
Author(s):  
Howell Bosbyshell ◽  
◽  
Andrew C. Ford
Keyword(s):  
Appalachian Piedmont ◽  
Metamorphic Gradient

Metamorphic discontinuities in the Pennsylvania – Delaware Piedmont: evidence for early Paleozoic assembly

1995 ◽  
Vol 32 (6) ◽  
pp. 686-698 ◽  
Author(s):  
J. Alcock ◽  
Mary Emma Wagner
Keyword(s):  
Temperature Inversion ◽  
Amphibolite Facies ◽  
Early Paleozoic ◽  
Tectonic History ◽  
History Of ◽  
Peak Metamorphism ◽  
High Grade Metamorphism ◽  
Appalachian Piedmont ◽  
Metaigneous Rocks ◽  
Metamorphic Gradient

Interpretation of the early Paleozoic tectonic history of the Appalachian Piedmont is commonly complicated by post-Taconian deformation that has disrupted and obscured early Paleozoic structure. Blocks that lie between zones where later deformation has been concentrated, however, may preserve evidence of Taconian high-grade metamorphism. In these cases, analysis of metamorphism allows an interpretation of the early Paleozoic tectonic history of the block and its surrounding region. A block of this type in the Pennsylvania–Delaware Piedmont includes three tectonic units: (1) the basement-cored massifs of southeastern Pennsylvania with Grenvillian gneiss unconformably overlain by the Setters Formation and Cockeysville Marble; (2) the Wilmington Complex arc terrane; and (3) the Wissahickon Group and associated metaigneous rocks. A metamorphic gradient and inferred temperature inversion within the Wissahickon Group and a metamorphic discontinuity at the Wissahickon Group–Cockeysville Marble contact are used to establish that the Wilmington Complex was first joined with the Wissahickon Group and that the two units were then emplaced together onto the rocks now exposed in the massifs. An observed correlation of amphibolite-facies mineral assemblages in the Cockeysville Marble with their distance from the Wissahickon Group indicates that peak metamorphism of the marble occurred after the metapelites were emplaced. As amphibolite-facies metamorphism of the basement-cored massifs has been previously dated as Taconian, it follows that the assembly of these tectonic units occurred in the early Paleozoic.

TERRANE ACCRETION AND TRANSPRESSION IN THE CENTRAL APPALACHIAN PIEDMONT: AN EXAMPLE FROM THE ENIGMATIC GOOCHLAND TERRANE

2020 ◽  
Author(s):  
Christopher M. Bailey ◽  
◽  
Hope J. Duke ◽  
Zachary Foster-Baril ◽  
Daniel F. Stockli
Keyword(s):  
Appalachian Piedmont ◽  
Terrane Accretion

Metamorphic Gradient: A Regional-Scale Area Selection Criterion for Gold in the Northeastern Superior Province, Eastern Canadian Shield

SEG Discovery ◽  
2007 ◽  
pp. 1-15
Author(s):  
Michel Gauthier ◽  
Sylvain Trépanier ◽  
Stephen Gardoll
Keyword(s):  
Regional Scale ◽  
Selection Criterion ◽  
Superior Province ◽  
James Bay ◽  
Area Selection ◽  
The North ◽  
First Pass ◽  
Abitibi Subprovince ◽  
Frontier Region ◽  
Metamorphic Gradient

ABSTRACT One hundred years after the first gold discoveries in the Abitibi subprovince, the Archean James Bay region to the north is experiencing a major exploration boom. Poor geologic coverage in this part of the northeastern Superior province has hindered the application of traditional Abitibi exploration criteria such as crustal-scale faults and “Timiskaming-type” sedimentary rocks. New area selection criteria are needed for successful greenfield exploration in this frontier region, and the use of steep metamorphic gradients is presented as a possible alternative. The statistical robustness of the metamorphic gradient area selection criterion was confirmed by using the curve of the receiver operating characteristic (ROC) to estimate the correlation between metamorphic fronts and the distribution of known Abitibi orogenic gold producers. The criterion was then applied to the James Bay region during a first-pass craton-scale exploration program. This was part of the strategy that led to the discovery of the Eleonore multimillion-ounce gold deposit in 2004.

Gold Exploration and Potential of the Appalachian Piedmont of Eastern Alabama

SEG Discovery ◽  
2013 ◽  
pp. 1-17
Author(s):  
Jim Saunders ◽  
Mark Steltenpohl ◽  
Robert B. Cook
Keyword(s):  
Massive Sulfide ◽  
Gold Deposits ◽  
Southern Appalachians ◽  
Sulfide Deposits ◽  
Gold Exploration ◽  
Geochemical Association ◽  
Carolina Slate Belt ◽  
Appalachian Piedmont ◽  
Metamorphic Terranes ◽  
Exploration Activity

ABSTRACT: The discovery and production of gold from epithermal and volcanogenic massive sulfide deposits in the Carolina slate belt of the southern Appalachians perhaps have overshadowed the gold potential of orogenic gold deposits in relatively higher grade metamorphic terranes of the southern Appalachian Piedmont. There has been a limited amount of exploration in the non-Carolina slate belt southern Appalachians since the early 1980s. Here we describe some of the recent exploration activity and geology of gold occurrences in the most productive part of the Alabama Piedmont, including the Goldville and Devil’s Backbone districts. In this area, there is a strong geochemical association of gold and arsenic in bedrock, saprolite, and soils, which reflects the mineralogical association of gold with arsenian pyrite and arsenopyrite in mineralized zones.

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