Age and provenance of the fluvial Goldstein Peak unit Diane Clemens-Knott, Department of Geological Sciences, California State University, Fullerton 92834
To study the extent to which new forearc basins are filled with purely arc-derived sediment, we used an LA-ICPMS at the Arizona Laserchron Center to measure the U-Pb dates of ≈60-100 detrital zircons from samples of • Early Cretaceous Goldstein Peak Formation (GP) = fluvial-lacustrine interarc basin fill • Early Cretaceous Gravelly Flat Formation (GF) of the Great Valley Group (GVG) = marine forearc deposits, & • older metamorphic rocks = the framework of the Sierra Nevada arc and likely sources of older, pre-arc zircons. comparison of PZ to PC detrital zircon dates from the metamorphic framework rocks to determine sediment correlations & provenance Detrital Zircon Ages
Reconstruction of the Early Cretaceous Goldstein Peak interarc basin connected to the Great Valley forearc basin
upper Gravelly Flat Fm (n=24)
Goldstein Peak Fm (n=258)
N lower Gravelly Flat Fm (n=58)
Kings Sequence (n=85)
Calaveras? Fm (n=147)
Slate Mtn = Snow Lake block? (n=173)
Hospital Rock = Zabriskie Quartzite? (n=86)
SCICON = Golconda thrust? (n=97) 0
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Age (Ma)
CSU Fullerton students “zapping” zircons at ALC Scientific Findings--Mesozoic Sediment Pathways Deposition of the newly discovered Goldstein Peak Fm. (GP) occurred in the Early Cretaceous (141+3 Ma). • this is the first nonmarine record west of the arc • The first marine forearc sediments (GF) are approximately coeval (143+5 Ma) and have a similar arc-derived provenance as the GP, one that is distinct from that of forearc sediments in the northern Great Valley. • By the Late Cretaceous, sediments of the entire Sierra Nevada forearc basin were well mixed. • The provenance of Jurassic Kings Sequence turbidites include reworked Paleozoic passive margin sediments (to the E) & zircons from the Klamath Mtns (from the N). •
• Educational Outcomes 6 BS theses (Crystal Castellanos, Kevin Tomita, Isaac Shirley, Josh Sobolew, Hector Fernandez, Natalie Hollis) and 2 MS theses (Mike Martin, Chris Buchen) 4 funded research experiences: undergrad Michael Prior (now in the PhD program at UT Austin), grad students Michelle Gevedon, Megan Murphy, Randal Morlan (CSUF) 8 student-faculty abstracts: presented at American Chemical Society, GSA, AAPG
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This provenance is similar to the Triassic marine sediments of the Calaveras Fm.(?) Zircon provenance characterization of arc framework rocks lead to the discovery of a sliver of the Golconda Thrust belt (from N. NV), probably translated southeast in the Permian, prior to MZ arc construction.
