The Thibert Project follows the surface expression of the Thibert Fault system with the Cache Creek Terrane on the south, Quesnel Terrane to the north. Terrane bounding faults are often deep seated and crustal scale, reactivated during accretionary strike slip tectonic faulting, and are important controls for mineralizing fluid conduits.
The exotic Cache Creek terrane represents a tectonically emplaced package of rocks with oceanic affinity that is separated from the volcanic and sedimentary rocks of the Quesnellia terrane by regional faults. These faults include the Thibert, Kutcho, and King Salmon faults.
The Cache Creek Complex is comprised of ultramafic rocks that are inferred to be Mississippian to Triassic in age. The Cache Creek complex represents upper mantle and lower crustal portions of an idealized ophiolite sequence. Also within the Cache Creek terrane are equivalent portions of an upper, younger portion of an ophiolite, comprised of mafic to intermediate volcanic and pelagic sediments. The Kedaha, and Inklin formations represent the upper most portion of an ophiolite, whereas the Kutcho and Nakina formations represent volcanic and intrusive rocks that are thought to be upper to lower crustal equivalents. Variably serpentinized peridotite is the most abundant lithology within the ultramafic units. Peridotite is comprised of predominantly harzburgite, lherzolite, and dunite. Peridotite is typically weathered orange/brown, and is dark green to black unweathered (fresh). Pyroxene bearing peridotites typically contain 10‐20% orthopyroxenes, minor augite and contain accessory chrome spinel and secondary magnetite.
Sedimentary rocks typically in fault contact with peridotite include phyllite, limestone and chert mapped as Kedaha and Inklin Formations. These fine grained, heterolithic siliciclastic rocks are typified by medium grey to black weathered, laminated to thinly bedded with variable degrees of deformation. Contact zones proximal to peridotite typically exhibit schistose textured argillite with quartz segregations and common bull‐quartz veins. Rare limestone lenses within the Kedaha formation are light grey weathered, medium grey fresh, and exhibit a fine grained, micritic composition.
