Oxygen isotopes of Pennsylvanian conodonts: surface water salinity in the US Midcontinent Sea

宾夕法尼亚牙形刺的氧同位素：美国中部大陆海的地表水盐度

• 批准号: 79275439
• 负责人: Professor Dr. Michael M. Joachimski
• 金额: --
• 依托单位: The University of Texas at San Antonio
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2008
• 资助国家: 德国
• 起止时间: 2007-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/79275439?language=en
• 关键词: Oxygen; isotopes; Pennsylvanian; conodonts; surface

Pennsylvanian glacio-eustatic sea-level variations resulted in the worldwide deposition of cyclic sediments in epeiric seas. Oxygen isotopes of conodont apatite from cyclothems in the USA and Russia were studied to constrain the amplitude of these sea-level changes. Oxygen isotope ratios of conodonts from the US Midcontinent cyclothems suggested that glacio-eustatic changes in sea-level were probably larger than 120 m. This estimate could not be confirmed by oxygen isotope analyses of conodonts from Russian cyclothems (Moscow basin and Ural foredeep). This discrepancy could be explained by changes in surface water salinity as consequence of enhanced river discharge during interglacial times, a factor previously not considered in our interpretation. This project focuses on potential salinity changes in surface waters of the US-Midcontinent Sea. We intend to study oxygen isotopes of conodonts from interglacial black shales along a transect from distal (Texas) to proximal parts (Ohio) of the US Midcontinent basin in order to document a salinity gradient in the basin. A salinity gradient is expected in case discharge from the Appalachian and Ouachita orogenic belts increased during the interglacial intervals. The new data are expected to contribute to a better understanding of the magnitudes of Pennsylvanian glacio-eustatic sea level changes.

宾夕法尼亚州的冰川海平面变化导致循环沉积物在高eir虫海洋中的全球沉积。研究了来自美国和俄罗斯的牙齿磷灰石的氧气同位素，以限制这些海平面变化的幅度。来自美国中部旋风的肌肌肌肌官的氧同位素比表明，海平面的冰川变化可能大于120 m。通过对俄罗斯环球体（莫斯科盆地和乌拉尔·菲德普）的肌肌肌肌肌组织分析，无法证实该估计值。由于冰间时期的河流排出增强，地表水盐度的变化可以解释这种差异，这是我们解释中以前未考虑的因素。该项目着重于美国 - 米德大陆海地水域的潜在盐度变化。我们打算研究从美国中部盆地的远端（德克萨斯州）到近端（俄亥俄州）的牙齿间黑色页岩的牙齿氧同位素，以记录盆地的盐度梯度。如果在冰河间间隔内从阿巴拉契亚语和瓦希塔造山带排出，则有望有盐度梯度。预计这些新数据将有助于更好地理解宾夕法尼亚冰川的海平面变化的幅度。