Chapter 2: The Heritage Group of the Ellsworth Mountains, West Antarctica

Abstract

The Heritage Group is composed of about 7,500 m of sedimentary strata exposed in the Heritage Range of the Ellsworth Mountains, West Antarctica. The Heritage Group is here redefined to include the Minaret Formation as the uppermost unit. New formations within the Heritage Group are formally described; they are, from the bottom upward, the Union Glacier, Hyde Glacier, Drake Icefall, Conglomerate Ridge, Springer Peak, Liberty Hills, and Frazier Ridge Formations. The Kosco Peak Member of the Union Glacier Formation is also formally described.Deposition of the Heritage Group took place in Middle and early Late Cambrian time in a rapidly subsiding basin bordered by carbonate rock and quartzite source areas of moderate relief. Sediment transport directions were dominantly from the present south and west. Thick, volcaniclastic terrestrial strata lie at the exposed base of the group, and these rocks grade upward into deltaic black shale and normal marine sediments. A number of active volcanic centers were present in the Heritage Range during the deposition of upper Heritage Group strata.

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

“…The Lower Paleozoic succession consists of the Lower (?) to Upper Cambrian Heritage Group (Webers et al, 1992a), and the overlying uppermost Cambrian (?) to Devonian Crashsite Group (Spörli, 1992).…”

Development of kinematic partitioning within a pure-shear dominated dextral transpression zone: the southern Ellsworth Mountains, Antarctica

“…The succession has been subdivided by Webers et al (1992a, b) into four apparently conformable formations; the Union Glacier, Drake Icefall, Conglomerate Ridge, and Springer Peak. However, recent mapping reveals that the contacts between those formations are in fact tectonic, some of which display structural discontinuity ( Fig.…”

“…Although tectonic contacts are present between the formations, there is little evidence to suggest that the stratigraphic order has been significantly disrupted or tectonically interleaved, as the dated formations, SPF and DIF (Buggisch et al 1992;Jago & Webers 1992;Shergold et al 1992;Webers et al 1992a, b), are in the correct stratigraphic order. However, these tectonic contacts do offer an alternative explanation for the lateral wedging of the CRF and Hyde Glacier Formation (not exposed in the southern Soholt Peaks) outcrops, which are currently proposed to be rapid lateral facies changes (Webers et al 1992a), but instead may be the result of tectonic juxtaposition.…”

“…However, these tectonic contacts do offer an alternative explanation for the lateral wedging of the CRF and Hyde Glacier Formation (not exposed in the southern Soholt Peaks) outcrops, which are currently proposed to be rapid lateral facies changes (Webers et al 1992a), but instead may be the result of tectonic juxtaposition.…”

“…Previous geological studies (Craddock 1972;Craddock et al 1992;SpOrli & Craddock 1992;Webers et al 1992a, b;Curtis 1997) concluded that the Ellsworth Mountains were deformed by…”