Detrital zircon U-Pb-He double dating: A method of quantifying long- and short-term exhumation rates in collisional orogens

Abstract

A U-Pb-He double-dating method is applied to detrital zircons with core-rim structure from the Ganges River in order to determine average short-and long-term exhumation rates for the Himalayas. Long-term rates are calculated from the U/Pb ages of metamorphic rims of the grains that formed during the Himalayan orogeny and their crystallization temperatures, which are calculated from the Ti-in-zircon thermometer. Short-term rates are calculated from (U-Th)/He ages of the grains with appropriate closure temperatures. The results show that short-term rates for the Himalayas, which range from 0.70  0.09 to 2.67  0.40 km/Myr and average 1.75  0.59 (1) km/Myr, are higher and more varied than the long-term rates, which range from 0.84  0.16 to 1.85  0.35 km/Myr and average 1.26  0.25 (1) km/Myr. The differences between the long-term and short-term rates can be attributed to continuous exhumation of the host rocks in different mechanisms in continental collision orogen. The U/Pb ages of 44.0 ± 3.7 to 18.3 ± 0.5 Ma for the zircon rims indicate a protracted episode of ~25 Myr for regional metamorphism of the host rocks at deeper crust, whereas the (U-Th)/He ages of 42.2 ± 1.8 to 1.3 ± 0.2 Ma for the zircon grains represent a protracted period of ~40 Myr for exposure of the host rocks to shallower crustal level. In particular, the oldest (U-Th)/He ages of the zircon grains are close to the oldest U/Pb ages for the rims, indicating that some parcels of the rocks that contain zircons were rapidly exhumed from deep to shallow levels in the stage of collisional orogeny. On the other hand, some parcels of the rocks may have been carried upwards by thrust faults in the post-collisional stage. The parcels could be carried upwards by the thrust faults that steepen as they near the surface, or by transient movement faults so that areas of rapid exhumation became areas of slow exhumation and visa versa on a time scale of a few Myr in order to maintain the continuous exhumation. In this regard, the Ganges River must be preferentially sampling areas that are currently undergoing above average rates of uplift.zircon, U-Pb-He double-dating method, Himalayas, exhumation rate, collisional orogen Citation:Wang C Y, Campbell I H, Reiners P W, et al. 2014. Detrital zircon U-Pb-He double dating: A method of quantifying long-and short-term exhumation rates in collisional orogens.

Sediment provenance and routing evolution in the Late Cretaceous–Eocene Ager Basin, south‐central Pyrenees, Spain

“…DZ U‐Pb‐He double dating has been shown to increase the robustness and resolution of DZ U‐Pb provenance analysis by combining U‐Pb crystallization ages and (U‐Th)/He cooling ages (ZHe) from individual DZ crystals, refining the identification of potential sources and constraining their thermal evolution (e.g. Campbell, Reiners, Allen, Nicolescu, & Upadhyay, ; Carrapa, DeCelles, Reiners, Gehrels, & Sudo, ; Dias et al, ; Fildani et al, ; Filleaudeau, Mouthereau, & Pik, ; Fosdick et al, ; Odlum et al, in ; Pujols, Leva López, Stockli, Rossi, & Steel, ; Rahl, Reiners, Campbell, Nicolescu, & Allen, ; Reiners, ; Reiners et al, ; Thomson et al, ; Wang, Campbell, Reiners, & Allen, ; Xu, Stockli, & Snedden, ). This approach has the potential to refine source identification by alleviating some limitations related to sediment recycling and non‐diagnostic U‐Pb ages in source regions (e.g.…”

Integrated single crystal laser ablation U/Pb and (U–Th)/He dating of detrital accessory minerals – Proof-of-concept studies of titanites and zircons from the Fish Canyon tuff

“…In recent years, a number of studies of this kind have been conducted, with special emphasis on combining U/Pb and either (U-Th)/He or fission-track methods, a procedure often referred to in the literature as 'double dating' (e.g. Rahl et al, 2003;Reiners et al, 2005;Bernet et al, 2006;Kirstein et al, 2010;Saylor et al, 2012;Painter et al, 2014;Tang et al, 2014;Wang et al, 2014). In some cases, all three techniques have been combined for 'triple dating' of detrital apatites (e.g., Carrapa et al, 2009;Zattin et al, 2012).…”

Zircon U‐Pb‐He Double Dating of Modern Sands From the Inn River Catchment: Assessing Resolution and Potential in a Complex Orogenic Setting

“…This double dating (DD) procedure unifies the advantages of these methods and allows highly specific discrimination of the sources (e.g., Carter & Moss, 1999; D. M. Chew & Donelick, 2012; Lu et al., 2020; Reiners et al., 2005). The best examples for the application of DD are the studies when detritus of the foreland basins associated with active or young orogens were dated (Pujols & Stockli, 2021; Thomson et al., 2017; Wang et al., 2014). Detrital grains with low‐T ages close to the age of deposition (i.e., short lag time, Garver et al., 1999) can derive either from coeval volcanism or from rapidly exhuming basement blocks.…”