Rio dating

He is particularly useful in geologic studies (e.g., Marchetti and Cerling, 2005; Foeken et al., 2009) because it is a stable nuclide that has the highest production rate of all TCNs, as well as a low detection limit on a noble gas mass spectrometer.He is produced primarily via spallation reactions on O, Mg, Si, Ca, Fe, and Al within olivine, pyroxene, hornblende, and garnet crystals.These climatic fluctuations have recently received considerable attention as a primary driver of fluvial incision in western U. river systems (e.g., Dethier, 2001; Connell et al., 2005; Mack et al., 2011).These unique aspects of the northern Rio Grande make it a critical place large enough to examine the geomorphic responses of a river system to a remarkable range of external (i.e., climate and large-scale tectonics) and internal (i.e., drainage integration, local tectonics, local sedimentation, and landslide damming) driving forces, yet smaller and with less inherent complexity than, for example, the Colorado River.The most prominent terrace surface (Qt4) falls within MIS 2 and appears to closely track incision associated with Pinedale ice retreat.Previous work suggests that the initiation of gorge incision occurred between ca.Here we use detailed field mapping and cosmogenic He surface-exposure geochronology of fluvial terraces to examine the incision history of this ∼5 km reach of the northern Rio Grande gorge in New Mexico.We use these observations to determine the timescales, rates, and potential drivers of incision in this section of the gorge, as well as how the proposed incision history here compares to other major river systems in the west-central United States.

Located deeper in the gorge topographically below the landslides is a flight of six fill and fill-cut terraces (Qt6–Qt1) at 50, 40, 28, 21, 10, and 8 m above the modern river.Rates of dynamic surface uplift and/or slip along basin-bounding normal faults associated with the Rio Grande rift are over an order of magnitude too small to explain the fast incision; thus we suggest the most probable driver of incision is drainage basin (re-)integration and transient knickpoint migration due to the capture of the northern San Luis Basin during the middle Pleistocene, superimposed on a strong climatic signature in the late Pleistocene.The Rio Grande of the southwestern United States has long been used as a natural laboratory for understanding fluvial processes, including the mechanisms and timescales of basin capture and drainage integration (e.g., Dethier et al., 1988; Connell et al., 2005; Mack et al., 2006), feedbacks between tectonic processes, river morphology and incision (e.g., Chapin and Cather, 1994; Mack et al., 2011; Repasch et al., 2017), and the role of local and global climatic events on river incision and aggradation (e.g., Dethier, 2001; Pazzaglia, 2005).This study focuses on a section of the Rio Grande gorge located within the tectonically active southern San Luis Basin of the northern Rio Grande rift in New Mexico (Fig. The San Luis Basin is a 10–100-km-wide, east-tilted, asymmetric half-graben that has experienced left-oblique extension since the late Oligocene, with the most rapid phase of regional extension occurring during the middle to late Miocene (Chapin and Cather, 1994).The basin is bounded on the east by the Sangre de Cristo normal fault and is transected by left-stepping en-echelon normal fault strands of the Red River fault zone (RRFZ) (Fig. The basin is occupied primarily by basaltic lavas of the Taos Plateau volcanic field; these lavas are interlayered with and underlain by Pliocene and late Miocene alluvial and fluvial sediments of the Santa Fe Group.

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