Trace element analyses, Sr and Nd isotopic data of shark teeth and sediments from La Meseta Formation, Seymour Island, Antarctica

The purpose of this study is to test the timing of Drake Passage opening using rare earth element (REE) concentrations, strontium, and neodymium isotope analyses on fossil shark teeth and neodymium isotopes on sediments from the Eocene La Meseta Formation , located on Seymour Island, in the Antarctic Peninsula, East Antarctica. The shark teeth εNd vary from -7 to -4, between present day Pacific and Atlantic seawater εNd values, and higher than associated sediments (εNd = -9 to -6), while 87Sr/86Sr show a narrow range 0.707722 to 0.707775, corresponding to Eocene seawater. The PAAS-normalized REE patterns show enrichment in the middle ones with respect to both light and heavy ones and no cerium anomalies. The data is used to infer the presence of Pacific seawater in the Atlantic sector of the Southern Ocean earlier than 41 My.

本研究的宗旨在于通过稀土元素（REE）浓度、锶和钕同位素分析，对古鲨齿及南极半岛东南极洲塞缪尔岛上的始新世La Meseta地层沉积物中的钕同位素进行分析，以验证德雷克海峡开启的时间。鲨齿中的εNd值介于现今太平洋和大西洋海水εNd值之间，从-7至-4，且高于相关沉积物（εNd = -9至-6），而87Sr/86Sr比值显示出较窄的范围，介于0.707722至0.707775之间，与始新世海水相匹配。PAAS标准化REE模式显示出相对于轻、重稀土元素而言，中稀土元素的富集，且未出现铈异常。这些数据被用于推断太平洋海水在41百万年前已存在于南大洋的 Atlantic sector。