ID-TIMS U-Pb ZIRCON RADIOMETRIC AGES FOR THE PENNSYLVANIAN-CISURALIAN TIME SCALE: IMPLICATIONS FOR GLOBAL CORRELATION AND RATES OF PROCESSES

宾夕法尼亚-中部时间尺度的 ID-TIMS U-Pb 锆石辐射年龄：对全球相关性和过程速率的影响

• 批准号: 0418703
• 负责人: Mark Schmitz
• 金额: --
• 依托单位: Boise State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-15 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0418703&HistoricalAwards=false
• 关键词: ID; TIMS; Pb; ZIRCON; RADIOMETRIC

Schmitz0418703The Late Pennsylvanian through Early Permian was an important interval in Earth's history.Significant events of this age include the final assembly and early evolution of Pangea, major eustaticchanges in sea level, and global climate change from the Pennsylvanian 'ice house' to the Permian 'hothouse.' Unfortunately, the poor temporal resolution of the geologic time scale during this intervalsubstantially limits our ability to clarify and correlate many aspects of late Paleozoic geologic history.Commonly cited time scales differ by as much as 14 Ma in the estimated age of the Pennsylvanian-Permian boundary, and vary by 500% in the inferred duration of various stages. Significant uncertaintiesin this part of the time scale arise because numerical ages assigned to period and stage boundaries arebased on linear interpolation between relatively sparse control points. Moreover, the existing controlpoints were obtained from geographically disparate stratigraphic sections, assigned positions in the timescale using several different taxa, and dated by several different radiometric techniques. Because muchfundamental research depends directly on the accuracy and precision of the geologic time scale,improving its age calibration is critical, and requires a robust, well-constrained, and internally-consistentframework of biostratigraphic and geochronologic data for the Late Carboniferous to Early Permian.This is a three-year multidisciplinary research effort to calibrate this interval of the time scaleusing the type sections and principal reference sections in the southern Ural foreland of Russia-Kazakhstan. Three aspects of the southern Urals make this an excellent laboratory for age calibration:first, the internationally accepted definition of the chronostratigraphic scale for Early Permian(Cisuralian) comes from this region, and it is a principal reference area for the Late Pennsylvanian aswell; second, late-Paleozoic marine fauna (including small foraminifera, fusulinids, conodonts, andammonoids) are numerous and well preserved, allowing precise biostratigraphic control; and third,interstratified volcanic ashes are common, making precise radiometric age control achievable. The proposed study will have truly global significance. Researchers worldwide working on a broadrange of Late Paleozoic problems will benefit directly and measurably from the results.

Schmitz0418703宾夕法尼亚晚期到早二叠世是地球历史上的一个重要时期。这个时代的重大事件包括盘古大陆的最终组装和早期演化，海平面的重大海平面变化，以及从宾夕法尼亚的冰屋到二叠纪的温室的全球气候变化。不幸的是，在这段时间内，地质时间尺度的时间分辨率很低，这大大限制了我们澄清和对比晚古生代地质历史的许多方面的能力。通常引用的时间尺度在宾夕法尼亚-二叠纪边界的估计年龄上相差高达14 Ma，在推断的不同阶段的持续时间上相差500%。由于分配给周期和阶段边界的数字年龄是基于相对稀疏的控制点之间的线性内插，因此在这部分时间尺度中出现了显著的不确定性。此外，现有的控制点是从地理上不同的地层剖面中获得的，使用几个不同的分类群在时间尺度上指定了位置，并通过几种不同的辐射测量技术确定了年代。由于许多基础研究直接依赖于地质时间尺度的准确性和精确度，因此提高地质时间尺度的年龄标定是至关重要的，并且需要一个健壮的、约束良好的、内部一致的晚石炭世至早二叠世的生物地层和地质年代学数据框架。这是一项为期三年的多学科研究工作，旨在利用俄罗斯-哈萨克斯坦南部乌拉尔前陆的类型剖面和主要参考剖面来标定这一时间尺度区间。乌拉尔南部的三个方面使其成为进行年龄校正的优秀实验室：首先，国际公认的早二叠世(西苏拉纪)年代地层标尺的定义来自该地区，它也是宾夕法尼亚晚期的主要参考区；第二，晚古生代海洋动物群(包括小有孔虫、丝虫、牙形刺和菊石)数量众多且保存良好，可以进行精确的生物地层控制；第三，层间火山灰很常见，因此可以进行精确的放射性年龄控制。这项拟议的研究将具有真正的全球意义。世界各地致力于晚古生代广泛问题的研究人员将直接和可测量地从结果中受益。