The newly named Three Valley Suite (TVS) kersantite lamprophyre to shoshonitic mafic dykes of the Monashee Complex are inferred to be hypabyssal feeder dykes to an alkaline to calc-alkaline volcanic suite related to the Kamloops Group. These dykes were emplaced in a subvertical north-trending orientation coincident with inferred Eocene crustal extension (~50.0 Ma), based on the flat 40Ar/39Ar step-heating plateau of contact-metamorphic muscovite on the margin of a TVS dyke. These weakly altered mafic dykes are fine grained with phenocrysts (0.5–2.0 mm) of phlogopite, augite, amphibole, and olivine (pseudomorphed by clays), rare labradorite, and both primary and secondary carbonates set in a fine-grained groundmass of similar mineralogy consistent with their classification as plagioclase-bearing potassic diorite to kersantite lamprophyre. The dykes are weakly silica-undersaturated and alkalic (2.8 wt.% K2O, 7.7 wt.% MgO), with high large ion lithophile element contents (~300 times primitive mantle) and elevated high-field-strength element contents, with a prominent negative Nb (Ta) anomaly, and have radiogenic Nd and Sr isotopic signatures; these geochemical attributes are consistent with a calc-alkaline shoshonitic affinity. Therefore, it is inferred that the subducting oceanic plate influenced subcrustal mantle wedge metasomatism in the region. Decompression partial melting of this metasomatised lithospheric mantle was initiated by coupled rapid unroofing, regional trans pression, slab rollback, and slab window development to the south. The TVS is similar to the mafic volcanic rocks within the nearby Eocene volcanic rocks, suggesting that these dykes represent the feeder system to a volcanic field that is now eroded, i.e., a broad-terrane association.

A common approach in the quantitative analysis of geological samples by X-ray fluorescence is to establish calibration lines for elements of interest by using several reference materials (RMs) and/or the combination of RMs and pure chemicals. Herein, we introduce an alternative to use only two RMs, to establish a calibration application. Variation of the dilution factor is employed to generate a dynamic range of concentrations for each RM and to evenly furnish the calibration lines to analyze certain matrices. A wide range of dilution factors were employed from 2-54 times dilution (with respect to the flux to sample ratios). Calibration lines for the major elements including: Si, Al, Ca, Fe, Mg, Na, Mn, and Ti show an extremely high level of linearity with all elements. R 2 values greater than 0.9990 were obtained for each analyzed element. The calibration application was validated by checking against a variety of geological RMs including petroleum and carbonate rich shale (SGR-1), Muscovite rich marine shale (SBC-1), metamorphic rock (SDC-1), carbonatite (COQ-1), and types of igneous rocks (GSP-2, BCR-2, AGV-2, QLO-1, and W-2). Mixtures of Alumina and Silica (ARG-1 and ARG-2) and pure SiO 2 beads were also analyzed to further check the application. Rigorous statistical analysis on the RMs confirms the reliability of the calibration application for the employed matrices.

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Regional and Local Geology……………………………………… Methods of Study………………………………………………………….. Water-Chemistry Sampling……………………………………….. 6 Water-Chemistry Analyses……………………………………….. Quality Assurance………………………………………………………… Chemical Data……………………………………………………………. References Cited………………………………………………………… 39 FIGURES 1. Map of Alaska with location of study area ……………………….... 2. Topographic map of Ester Dome, Alaska with sampling site locations…………………………………………………………….. 3. Comparison of analytical results by ICP-AES and ICP-MS for Ba, Mn, and Sr. …………………………………………………. TABLES 1. Sampling site locations…………………………………………... 2. Methods of analysis and detection limits………………….………. 8 3. Dissolved organic carbon determinations ………………………… 4. 34 S and 18 O isotope determinations………………………………... 10 5. Results of water analyses of Ester Dome, Alaska………………….

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