Marine palynomorph abundance estimates of sediment core CRP-2A (Fig. 2)

A diverse assemblage of marine palynomorphs was recovered from the Oligocene - Miocene section of CRP-2/2A. Most of the assemblage is composed of previously unrecognised species. Three distinct groups of marine palynomorph were recognised: (1) prasinophytes, mainly Cymatiosphaera, (2) acritarchs, mainly Leiosphaeridia and Sigmopollis although Leiofusa is an important component of the bottom half of the hole, and (3) dinoflagellate cysts. About 27 species of in situ dinoflagellate cysts were recorded, of which seven apparently undescribed species of Lejeunecysta form a prominent component. Reworked specimens of several species of the Paleogene Transantarctic Flora occur in CRP-2/2A sediments. Several abundance peaks of reworked taxa from the Transantarctic Flora are recorded. Three marine palynomorph zones were recognised (MP3, MP2, MP1), considered to be early Oligocene, late Oligocene, and late Oligocene/early Miocene in age respectively. Samples from the Quaternary and Pliocene part of CRP-2/2A were also examined. These proved either barren or yielded very sparse low diversity floras.

本研究从CRP-2/2A井的渐新世-中新世地层中采集得到一套多样的海洋孢粉型化石（marine palynomorphs）组合。该组合中绝大多数物种均为此前未被报道的新类群。研究识别出三类截然不同的海洋孢粉型化石类群：（1）绿藻（prasinophytes），以顶棘藻属（Cymatiosphaera）为主；（2）疑源类（acritarchs），主要涵盖光滑球囊藻属（Leiosphaeridia）与粉囊藻属（Sigmopollis），但梭形球囊藻属（Leiofusa）是该井段下半部分的重要组成类群；（3）沟鞭藻囊孢（dinoflagellate cysts）。本次研究共记录到27种原位沟鞭藻囊孢，其中勒让囊藻属（Lejeunecysta）的7个疑似未描述新物种构成了该类群的核心组分。CRP-2/2A沉积物中还发现了古近纪南极植物区系（Paleogene Transantarctic Flora）多个物种的再沉积标本，同时记录到该植物区系再沉积类群的多个丰度峰值。本研究识别出3个海洋孢粉型化石组合带（MP3、MP2、MP1），其形成时代分别对应早渐新世、晚渐新世以及晚渐新世/早中新世。此外，本研究还对CRP-2/2A井的第四纪与上新世地层样品开展了分析，结果显示这些样品要么不含任何化石，要么仅产出丰度极低、多样性贫乏的类群组合。