UPb geochronological constraints on the timing of plutonism, volcanism, and sedimentation, Jersey, Channel Islands, UK
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Uraniumlead dates for single and small multiple grain zircon separates are presented for the main geological units from Jersey, British Channel Islands. A turbiditic sandstone from the Jersey Shale Formation (Brioverian Supergroup) contains detrital zircons of a variety of ages, ranging from c. 2.6 to 0.6Ga. The youngest zircons yielded nearly concordant UPb dates of 586.73.0Ma and 587.12.7Ma providing a maximum depositional age for the unit. Zircons from overlying volcanic rocks (Anne Port Rhyolite) give an upper intercept date of 582.8 +32.7 Ma, considered to be the age of eruption. The undeformed SW Jersey granite, which intrudes and locally thermally metamorphoses the folded Jersey Shale Formation, is dated at 580 +2.31.6 Ma. These dates constrain tightly the timing of deposition of the Jersey Shale Formation and the age of deformation on Jersey, and indicate a dynamic arc environment during the late Neoproterozoic. Zircons from the NW Jersey granite define an upper intercept date of 482.71.6Ma, similar to the previously reported 40 Ar/ 39 Ar hornblende date of c. 473Ma, confirming a renewed pulse of magmatism during the Ordovician in this sector of Cadomia.
