Faculty Mentor

Chad Pritchard

Presentation Type

Poster

Primary Discipline of Presentation

Geosciences

Abstract

Nestled in northeastern Washington, the Shedroof Formation is very poorly constrained geologic unit. This project focuses on defining the unit, deciphering its structural history, and discover its connection to an inland temperate rainforest that grows within its fractures and soils. Additionally, it will assist in further constraining the age of the Neoproterozoic rifting event of Columbia, in which the Mawson Continent (now possibly southern Australia) presumably separated from western Laurentia (Box et al, 2020). Preliminary mapping has identified a pyrite rich metaconglomerate (Figure 3c) most closely corresponding with the Neoproterozoic Monk Formation based off of general rock descriptions. A two-meter-thick metaconglomerate to ultra mylonite (Figure 3f) cross-cutting a southerly dipping conglomerate follows the general contact of the Neoproterozoic Monk and Shedroof Formations, which may correlate to the severely understudied Newport fault (Harms and Price, 1992). The Newport fault is potentially a source of said massive mylonite zone and further age determination of these formations and structures will answer a number of basic stratigraphic and complex structural questions. The Shedroof Formation was previously presented as equivalent to the Deer Trail Group (Miller, 1994), however may now be a Buffalo Hump equivalent of the Windermere Supergroup (Box et al., 2020; Brennan et al. 2020).

Download

Share

COinS
 

Deciphering the Shedroof Formation, a Proterozoic conglomerate structurally (?) overlying the Belt Supergroup in N Idaho and NE Washington

Nestled in northeastern Washington, the Shedroof Formation is very poorly constrained geologic unit. This project focuses on defining the unit, deciphering its structural history, and discover its connection to an inland temperate rainforest that grows within its fractures and soils. Additionally, it will assist in further constraining the age of the Neoproterozoic rifting event of Columbia, in which the Mawson Continent (now possibly southern Australia) presumably separated from western Laurentia (Box et al, 2020). Preliminary mapping has identified a pyrite rich metaconglomerate (Figure 3c) most closely corresponding with the Neoproterozoic Monk Formation based off of general rock descriptions. A two-meter-thick metaconglomerate to ultra mylonite (Figure 3f) cross-cutting a southerly dipping conglomerate follows the general contact of the Neoproterozoic Monk and Shedroof Formations, which may correlate to the severely understudied Newport fault (Harms and Price, 1992). The Newport fault is potentially a source of said massive mylonite zone and further age determination of these formations and structures will answer a number of basic stratigraphic and complex structural questions. The Shedroof Formation was previously presented as equivalent to the Deer Trail Group (Miller, 1994), however may now be a Buffalo Hump equivalent of the Windermere Supergroup (Box et al., 2020; Brennan et al. 2020).