Abundance of ostracoda in sediment cores CRP-1 and CRP-2

Sparse, poorly preserved late Oligocene (3 species) and early Miocene (4 species) ostracod faunas have been recovered from CRP-2A, while relatively more abundant Quaternary faunas occur in CRP-1 (24 species). All taxa are marine. No definitive age assignments can be made on the two older faunas, which are not considered to be in situ, although the taxa identified are not at variance with sediment ages determined on other grounds. The Oligocene ostracods (Lithostratigraphical Unit, LSU 9.4) suggest deposition in cold, relatively shallow, shelf waters with faunal connections to the Antarctic Peninsula and South America, while the Miocene fauna (LSU 5.1) is considered to be a cool-cold, deeper water (?outer shelf) association with faunal connections to both New Zealand and the Antarctic Peninsula. The Quaternary faunas are primarily from LSU 3.1 (carbonate-rich layer), and suggest deposition in very cold, relatively quiet water that was at least 100 m, and possibly 130-200 m deep. None of the taxa are known from pre-Pleistocene sediments, and all occur in modern Antarctic/sub-Antarctic regimes, predominantly from south of 60° S. Specimens in the "carbonate-rich layer" probably have suffered minor penecontemporaneous fractionation, while the fauna in LSU 2.2 has suffered more extensive post-mortem transportation and possible reworking (though not necessarily from pre-Quaternary sources).从CRP-2A钻孔中采集获得的介形类（ostracod）动物群保存状况较差且分布零散，其中渐新世晚期动物群含3个物种，中新世早期动物群含4个物种；而CRP-1钻孔中产出的第四纪介形类动物群相对更为丰富，共计24个物种。所有类群均为海相生物。 两套年代更老的动物群无法确定确切的地质年代归属，且被认为并非原位（in situ）埋藏，尽管已识别的类群与通过其他手段测定的沉积物年代并不矛盾。 产自岩石地层单位（Lithostratigraphical Unit, LSU）9.4的渐新世介形类动物群指示当时沉积环境为寒冷、相对较浅的陆架海域，该动物群与南极半岛及南美洲的生物群存在区系联系；而产自LSU 5.1的中新世介形类动物群则被认为是冷-寒温型深水（？外陆架）组合，其生物区系联系同时涉及新西兰与南极半岛。 第四纪介形类动物群主要产自LSU 3.1（富碳酸盐岩层），指示沉积环境为极度寒冷、相对安静的水体，水深至少100米，可能介于130-200米之间。 所有已发现的介形类类群均未在更新世之前的沉积物中被报道过，且均现生存在南极/亚南极海域生境，主要分布于南纬60°以南区域。 “富碳酸盐岩层”中的介形类标本可能遭受了轻微的准同生分异作用，而LSU 2.2中的动物群则经历了更为显著的死后搬运与可能的再沉积作用（尽管其来源未必来自第四纪之前的沉积物）。