Chapter 7: Middle Cambrian trilobites from the Ellsworth Mountains, West Antarctica

Provenance and age constraints of Paleozoic siliciclastic rocks from the Ellsworth Mountains in West Antarctica, as determined by detrital zircon geochronology

“…The Union Glacier Formation is locally overlain by the Hyde Glacier Formation, a laterally discontinuous unit of fluvial to shallow-marine deltaic deposits (Webers et al, 1992a). Overlying both of these formations is the Drake Icefall Formation, which is composed of black shales and interbedded limestones with middle Cambrian trilobite fauna (Jago and Webers, 1992), considered to represent shallow-marine sedimentation (Webers et al, 1992a). Overlying the Drake Icefall Formation through a reverse fault contact is the Conglomerate Ridge Formation, which is composed of quartzite, conglomeratic quartzites, and polymict conglomerates (Webers et al, 1992a).…”

“…Current interpretations indicate that they represent a continental rift setting, and they have been dated as middle Cambrian . This age is based on the presence of a trilobite fauna in the Springer Peak Formation (Jago and Webers, 1992;Shergold and Webers, 1992) and dating of granite clasts from a conglomerate unit in the Liberty Hills Formation, which constrains the maximum depositional age at 525 ± 2 Ma (multigrain U-Pb zircon upper-intercept age; Randall et al, 2000).…”

Revised Biostratigraphy, Systematics, and Paleobiogeography of the Trilobites from the Middle Cambrian Nelson Limestone, Antarctica

“…Solenopleura as defined currently likely represents a para-or even polyphyletic genus, as Cooper, Jago, and Begg (1996, p. 378) intimated. Thus, the relationships of S. pruina to such taxa as Sohopleura drakensis Jago and Webers, 1992, and Reillopleura braddocki Cooper, Jago, and Begg, 1996, cannot be determined. It is not inconceivable that S. pruina and S. reillyense might instead be referable to Sohopleura Webers, 1992, to Reillopleura Cooper, Jago, andBegg, 1996, or even to some other genus but until a detailed phylogenetic analysis of this family can be performed this cannot be determined with any degree of precision.…”

“…Encarnaci6n, Rowell, and Grunow (1999) concluded that the Taylor Formation was probably Undillan, though it could be upper Floran or less likely lower Boomerangian. Cooper, Begg, and Bradshaw, 1990;Cooper, Jago, and Begg, 1996;Cooper and Shergold, 1991;Jago and Webers, 1992;Evans, Rowell, and Rees, 1995;Encarnacién, Rowell, and Grunow, 1999), and here correlations will be made with the Australian stage names using the general global-correlation scheme of Peng and Robison (2000). This correlation scheme, although not based specifically on Antarctic sections, corresponds closely to schemes that do, e.g., Cooper and Shergold (1991).…”

“…Cocks (1989), Cooper and Shergold (1991), Cooper, Begg, and Bradshaw (1990), Cooper, Jag°, and Begg (1996) Jago and Webers (1992), Wolfart (1994), and Palmer and Rowell (1995) have all presented detailed syntheses of early Paleozoic Antarctic paleobiogeography. Five regions were treated in the biogeographic analysis: East Figure 6.…”