Major-oxide and trace-element geochemical data from rocks collected in 2018 for the Northeast Tanacross project, Tanacross C-1, C-2, D-1, and D-2 quadrangles, Alaska

Regional correlation of metamorphic rocks in the Ladue River-Mount Fairplay map area using trace-element geochemistry

“…The Lake George samples in the Northeast Tanacross map area include a higher proportion of MORB basalts exhibiting less crustal contamination compared to those in the Ladue River-Mount Fairplay area, and the Northeast Tanacross area also includes more numerous interlayered amphibolites, which may be a result of differing proximity to eruptive centers during continental rifting. Some amphibolites from the Lake George assemblage collected from the northeastern Tanacross quadrangle from different sample localities than from those reported in Wypych and others (2017;2018), as well as some from the Big Delta and Healy quadrangles west and southwest of our study area, respectively, have within-plate (OIB) trace-element signatures (Dusel-Bacon and Cooper, 1999;Dusel-Bacon and others, 2004) indicative of rifting.…”

“…This interpretation would account for similarities to both the Snowcap and Fortymile River/Finlayson assemblages. Additionally, the Ladue River unit may represent a complex, structurally interleaved boundary between the Snowcap and Fortymile (Wypych and others, 2017;2018) and the Finlayson and Snowcap assemblages in Yukon (Piercey and others, 2002;Piercey and Colpron, 2009). A. Magma series discrimination diagram of Winchester and Floyd (1977).…”

“…Greenstone (^gs) within the Jarvis belt units in the map area is lithologically similar to Triassic metagabbros in the Alaska Highway corridor (Solie and others, 2019), the Tok River map area (Sicard and others, 2017), and the Delta mineral belt (Dashevsky and others, 2003). Trace-element geochemistry was not Trace-element geochemistry of amphibolites collected in the Lake George assemblage within the Ladue River-Mount Fairplay map area with comparison to Lake George assemblage amphibolites collected within the adjacent Northeast Tanacross map area (Wypych and others, 2017;2018) and amphibolite samples in Dusel-Bacon and Cooper (1999). A. Magma-series discrimination diagram of Winchester and Floyd (1977).…”

“…Correlation of the Lake George assemblage with the same unit in the Northeast Tanacross map area to the north is well supported by overlap of amphibolite trace-element geochemistry (fig. 1; Wypych and others, 2017;2018). The Lake George samples in the Northeast Tanacross map area include a higher proportion of MORB basalts exhibiting less crustal contamination compared to those in the Ladue River-Mount Fairplay area, and the Northeast Tanacross area also includes more numerous interlayered amphibolites, which may be a result of differing proximity to eruptive centers during continental rifting.…”

New geologic investigations of northeast Tanacross (presentation): Alaska Miners Association Annual Convention, Anchorage, Alaska, November 4-10, 2018

“…Porphyry-type Cu-Mo-Au and 2) distal, gold-only systems are present here Both related to intrusive centersWypych et al 2017 andWypych et al 2018 …”