Cenozoic Coccolith Collection of David Bukry in Oregon and Washington, USA

Micropaleontological data have provided essential stratigraphic age control for geologic investigations in the Cascadia forearc, such as the Coast Range-Olympic Mountains and Puget-Willamette Lowland west of the Cascade Range. Foraminiferal assemblages and, later, coccoliths (calcareous nanoplankton) have been the most abundant microfossils recovered from the Cenozoic sequence. The usefulness of coccolith assemblages for establishing the Cenozoic stratigraphic framework (especially the Paleogene) in western Oregon was brought to the attention of Parke D. Snavely, Jr. in the 1960s by a letter from Dr. M. N. Bramlette of the Scripps Institution of Oceanography. Dr. Bramlette reported to Snavely that coccoliths in the Tyee Formation of western Oregon are correlative to “Laiming’s A2 zone of the Canoas Member” of the Kreyenhagen Formation in California (Bukry and Snavely, 1988). Dr. David Bukry, also of the USGS, joined Snavely’s geologic investigation team in the mid-1960s and provided the coccolith zonal assignments for many of the Cenozoic units in the Cascadia forearc. Coccolith information was originally reported to the collector in written form. Report sheets, accumulated over the past 30 years, served as the source of the data entered in the coccolith database.

微古生物学数据为卡斯卡迪亚前陆（Cascadia forearc）的地质调查提供了关键的地层年代约束，研究区域涵盖喀斯喀特山脉西侧的海岸山脉-奥林匹克山脉及皮吉特-威拉米特低地（Puget-Willamette Lowland）。有孔虫组合（Foraminiferal assemblages）以及后续的颗石藻（coccoliths，钙质超微浮游生物，calcareous nanoplankton）是新生代地层序列（Cenozoic sequence）中产出最为丰富的微体化石。1960年代，美国斯克里普斯海洋研究所（Scripps Institution of Oceanography）的M·N·布拉姆利特（M. N. Bramlette）博士致信小帕克·D·斯纳夫利（Parke D. Snavely, Jr.），令其认识到颗石藻组合在建立俄勒冈州西部新生代地层框架（尤其是古近纪（Paleogene））方面的重要价值。布拉姆利特博士向斯纳夫利告知，俄勒冈州西部泰伊组（Tyee Formation）中的颗石藻与加利福尼亚州克雷恩哈根组（Kreyenhagen Formation）的卡诺阿斯段（Canoas Member）“莱明A2带（Laiming’s A2 zone）”可进行地层对比（Bukry与Snavely，1988）。同样任职于美国地质调查局（USGS）的戴维·布克里（David Bukry）博士于1960年代中期加入斯纳夫利的地质调查团队，为卡斯卡迪亚前陆内诸多新生代地层单元提供了颗石藻带划分方案。颗石藻相关信息最初以书面形式提交给资料收集者。过去30年间积累的报告表，是本次颗石藻数据库所收录数据的原始来源。