Palaeoenvironmental reconstruction of Livingston Island, Antarctic Peninsula, in the Early Cretaceous: interpretations from the Walker Bay erratics

摘要

Chen, K., Stilwell, J.D. & Mays, C., 12.3.2015. Palaeoenvironmental reconstruction of Livingston Island, Antarctic Peninsula in the Early Cretaceous: interpretations from the Walker Bay erratics. Alcheringa 39, 000-000. ISSN 0311-551Fossiliferous, volcaniclastic sandstone erratics, containing abundant plant fragments, palynomorphs and a possible insect wing, were extracted from the previously unstudied Walker Bay moraine, Livingston Island (ca 62 degrees 36'S, 60 degrees 42'W). These samples provide new insights into high southern latitude ecosystems of the South Shetland Islands region during the Early Cretaceous greenhouse interval. The palynofloral assemblage, in particular the co-occurrence of Ischyosporites punctatus, Concavissimisporites penolaensis and Reticulatisporites pudens, suggests that deposition could have occurred between the early Aptian and mid-Albian (ca 125-109 Ma), but was most likely early to mid-Albian (ca 112-109 Ma). The high relative abundance of the pteridophyte taxon, Cyathidites and associated fungal disaster taxa, together with significant quantities of volcaniclastic material, indicates a volcanically perturbed post-eruption riparian environment. Petrologic evidence suggests that the volcanic sediments were deposited rapidly in the above-mentioned fluvial setting. Comparisons to geological studies conducted on Livingston Island reveal an affinity of the Walker Bay erratics to the Byers Group; the unique palynofloral assemblage and petrological features of the erratics suggesting that the volcanogenic lithic sandstone facies may represent a previously undescribed unit of the upper Cerro Negro Formation.