Testing for high-frequency (104-105 yr) glacio-and thermo-eustasy in greenhouse and transtional climates using oxygen isotopes of conodont apatite

使用牙形石磷灰石的氧同位素测试温室和过渡气候期间的高频冰川和/或热游动。高频率（104-105年）的上浅碳酸盐旋回是常见的沉积特征，通常归因于轨道驱动的冰川-游动（冰量变化）。但在温暖的温室条件下，冰川被认为并不重要，这使得这种对高频碳酸盐旋回的解释不那么令人信服。我们将通过分析牙形刺（一种常见的由成岩抗性磷酸盐组成的化石）的氧同位素比率来评估在温暖气候下发生冰川-游动的可能性。冰川冰强烈地含有氧的轻稳定同位素。因此，当存在大量冰（低海平面）时，海洋的氧同位素比率就会明显变大。抗成岩牙形刺将使我们能够寻找这一信号，并解决长期争论的暂时持续和广泛的米尺度碳酸盐旋回/准层序的起源，特别是有争议的瞬时冰盖甚至在温暖气候时期也能形成的提议是否合理并得到地球化学证据的支持。我们的研究将集中在三个温室（晚志留世、早泥盆世和早三叠纪）和一个过渡（早密西世）气候模式上。我们计划将当地的初中和高中科学教师纳入我们的研究项目，以帮助将科学探究带入课堂。这将通过与西南科学教育研究所（SEIS）合作，并通过举办一系列为期一周的夏季讲习班，以培养科学专业教师来实现。

Testing for high-frequency glacio- and/or thermo-eustasy during greenhouse and transitional climates using oxygen isotopes of conodont apatite.Maya Elrick and Zachary SharpUniversity of New MexicoEAR-0920830ABSTRACTHigh-frequency (104-105 years) upward-shallowing carbonate cycles are common sedimentary features and are generally attributed to orbitally driven glacio-eustasy (changes in ice volume). But in warm, greenhouse conditions, glacial ice is thought not to have been significant, making this interpretation for high frequency carbonate cycles less compelling. We will evaluate the possibility that glacio-eustasy did occur in warm climates by analyzing oxygen isotope ratios of conodonts, a common fossil composed of diagenetically-resistant phosphate. Glacial ice strongly incorporates the light stable isotope of oxygen. Therefore, when large ice volumes are present (low sea level), the oxygen isotope ratio of the ocean becomes measurably heavier. The diagenetically resistant conodonts will allow us to search for this signal and address the long-debated origin of temporally persistent and widespread meter-scale carbonate cycles/parasequences, specifically whether the controversial proposal that transient ice sheets can form even in warm climatic periods is reasonable and supported by geochemical evidence. Our study will center on three greenhouse (Late Silurian, Early Devonian and Early Triassic) and one transitional (Early Mississippian) climatic mode. We plan to incorporate local middle and high school science teachers into our research project to help bring scientific inquiry into the classroom. This will be accomplished through collaboration with the Science Education Institute of the Southwest (SEIS), and by conducting a series of week-long summer workshops for professional teacher development in the sciences.