Quaternary through early Eocene benthic foraminifera off Peru

Stratigraphic assemblages of Quaternary through early Eocene benthic foraminifers were recovered among 10 Peru margin drill sites. Various hiatuses and intervals barren in foraminifers characterize the sections, but numerous samples contain abundant, well-preserved benthic foraminifers.
Bathymetry of the extant species and California-based estimates of the paleobathymetry of the extinct species permit recognition of Quaternary sea-level fluctuations between shelf and upper bathyal depths that produced vertical migrations of oxygenated and low-oxygen habitats at the six shallow sites. Assemblages from lower-slope sites at about 9° and 11°S indicate a general subsidence of the continental margin from shelf or upper bathyal depths in Eocene time to the present lower bathyal depths. Data from 11°S suggest a major part of this subsidence occurred in late Oligocene to early Miocene time. Downslope-transported shelf specimens, particularly the small biserial species, Bolivina costata and B. vaughani, are major contributors to these lower bathyal assemblages from the middle Miocene through Quaternary time.

本数据集依托秘鲁海域10个钻探站位，获取了自第四纪至始新世早期的底栖有孔虫（benthic foraminifers）地层组合。各岩芯剖面均发育多段沉积间断及有孔虫贫乏层段，但多数样品中产出丰富且保存完好的底栖有孔虫。
通过分析现生种的现代水深数据，以及基于加州研究团队的灭绝种古水深（paleobathymetry）估算结果，可识别出6个浅水区站位在第四纪期间发生的陆架至半深海上带海平面波动，该波动驱动了含氧生境与低氧生境的垂直迁移。来自南纬约9°及11°斜坡下部站位的有孔虫组合显示，该大陆边缘整体经历了从始新世时期的陆架或半深海上带深度，沉降至现今半深海下带深度的过程。南纬11°站位的数据表明，该沉降过程的主要阶段发生于渐新世晚期至中新世早期。自中新世中期至第四纪，经斜坡搬运的陆架标本（尤其是小型双列壳类饰形玻提诺虫（Bolivina costata）与沃恩玻提诺虫（B. vaughani））是这些半深海下带组合的主要组成部分。