DOI: 10.5194/cp-11-1599-2015
Scopus记录号: 2-s2.0-84949204463
论文题名: Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the southwest Pacific
作者: Pascher K.M. ; Hollis C.J. ; Bohaty S.M. ; Cortese G. ; McKay R.M. ; Seebeck H. ; Suzuki N. ; Chiba K.
刊名: Climate of the Past
ISSN: 18149324
出版年: 2015
卷: 11, 期: 12 起始页码: 1599
结束页码: 1620
语种: 英语
Scopus关键词: Antarctic Circumpolar Wave
; arctic environment
; circumpolar current
; cooling
; depositional environment
; Eocene
; Eocene-Oligocene boundary
; fossil assemblage
; isotopic ratio
; Oligocene
; paleoclimate
; planktonic foraminifera
; radiolaria
; taxonomy
; Campbell Plateau
; Pacific Ocean
; Pacific Ocean (Southwest)
; Bacillariophyta
英文摘要: The long-term cooling trend from middle to late Eocene was punctuated by several large-scale climate perturbations that culminated in a shift to "icehouse" climates at the Eocene-Oligocene transition. We present radiolarian micro-fossil assemblage and foraminiferal oxygen and carbon stable isotope data from Deep Sea Drilling Project (DSDP) sites 277, 280, 281, and 283 and Ocean Drilling Project (ODP) Site 1172 to identify significant oceanographic changes in the southwest Pacific through this climate transition (∼ 40-30 Ma). We find that the Middle Eocene Climatic Optimum at ∼ 40 Ma, which is truncated but identified by a negative shift in foraminiferal δ18O values at Site 277, is associated with a small increase in radiolarian taxa with low-latitude affinities (5 % of total fauna). In the early late Eocene at ∼ 37 Ma, a positive oxygen isotope shift at Site 277 is correlated with the Priabonian Oxygen Isotope Maximum (PrOM). Radiolarian abundance, diversity, and preservation increase within this cooling event at Site 277 at the same time as diatom abundance. A negative δ18O excursion above the PrOM is correlated with a late Eocene warming event (∼ 36.4 Ma). Radiolarian abundance and diversity decline within this event and taxa with low-latitude affinities reappear. Apart from this short-lived warming event, the PrOM and latest Eocene radiolarian assemblages are characterised by abundant high-latitude taxa. High-latitude taxa are also abundant during the late Eocene and early Oligocene (∼ 38-30 Ma) at DSDP sites 280, 281, 283 and 1172 and are associated with very high diatom abundance. We therefore infer a northward expansion of high-latitude radiolarian taxa onto the Campbell Plateau in the latest Eocene. In the early Oligocene there is an overall decrease in radiolarian abundance and diversity at Site 277, and diatoms are scarce. These data indicate that, once the Antarctic Circumpolar Current was established in the early Oligocene (∼ 30 Ma), a frontal system similar to present day developed, with nutrient-depleted Subantarctic waters bathing the area around DSDP Site 277, resulting in a more restricted siliceous plankton assemblage. © 2015 Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/49092
Appears in Collections: 气候变化与战略
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Recommended Citation:
Pascher K.M.,Hollis C.J.,Bohaty S.M.,et al. Expansion and diversification of high-latitude radiolarian assemblages in the late Eocene linked to a cooling event in the southwest Pacific[J]. Climate of the Past,2015-01-01,11(12)