Sandstone petrofacies of detrital zircon samples from Paleozoic and Triassic strata in suspect terranes of northern Nevada and California

Abstract

We collected 35 sandstones and metasandstones for analysis of detrital zircons from Paleozoic and Triassic strata in suspect terranes of northern Nevada and northern California that represent five generic petrofacies: subarkose eroded from uplifted continental basement, quartzarenite (matrix-poor and matrix-rich subfacies) derived from cratonal sources, quartzolithic (quartz-rich, chert-rich, and quartzolithic-volcaniclastic subfacies) derived from recycled orogenic sources, volcaniclastic from volcanic arc structures, and volcanoplutonic from a dissected magmatic arc. Precambrian ages of dominant detrital zircons in the subarkose petrofacies (exclusively Harmony Formation of Cambrian age) and in most samples of the lower to middle Paleozoic quartzarenite petrofacies in the Roberts Mountains allochthon, the Shoo Fly Complex, and the Yreka terrane reflect a provenance in northern Laurentia or a continental block other than Laurentia. Samples from the lower part of the Vinini Formation in central Nevada are the only examples of the quartzarenite petrofacies yielding zircon populations that could have been derived from adjacent southwestern segments of Laurentia. Dominantly Grenville-age zircons in subordinate quartzose sandstones from the mainly subarkosic Harmony Formation suggest derivation from farther south along the Cordilleran continental margin. Zircons in the quartzolithic petrofacies were largely recycled into varied Paleozoic-Mesozoic overlap assemblages and successor basins, including the Havallah sequence of the Golconda allochthon, from older sedimentary sources in lower to middle Paleozoic strata of underlying or nearby terranes. Phanerozoic zircons in the upper Paleozoic to lower Mesozoic volcaniclastic petrofacies of the Sierran-Klamath belt reflect sources in coeval or older volcanic arc assemblages, with homogeneous age populations in each sample. Latest Precambrian and Grenville-age zircons in the volcanoplutonic petrofacies (one sample from the Sierra City melange) reflect sources in a magmatic arc that was not part of the Cordilleran miogeoclinal margin. The close correlations between petrofacies compositions and the age spectra of detrital zircon populations provide significant and consistent constraints for interpretations of regional tectonic history, the two datasets jointly offering more interpretive insight than either affords alone.