Stratigraphy and chronology of Provo shoreline deposits and lake‐level implications, Late Pleistocene Lake Bonneville, eastern Great Basin, USA
Stratigraphy and chronology of Provo shoreline deposits and lake‐level implications, Late Pleistocene Lake Bonneville, eastern Great Basin, USA
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普罗沃海岸线沉积物的地层学和年代学以及湖平面的影响，晚更新世美国东部大盆地邦纳维尔湖
DOI：
10.1111/j.1502-3885.2012.00297.x
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发表时间：
2013
期刊：
影响因子：
2.2
通讯作者：
J. McGeehin
中科院分区：
文献类型：
--
作者：
David M. Miller;C. Oviatt;J. McGeehin
邦纳维尔湖的普罗沃湖岸线是在邦纳维尔洪水之后形成的，并且根据之前的测年，形成于大约 17.5 到 15.0 cal 的溢流期间。卡。在许多地方，普罗沃海岸线由一对不同的海岸线组成，其中一条比另一条高约 3 米。我们提供了两次穿过双海滩的数据，表明上海滩更年轻，代表了湖位上升后的沉积作用。此外，较低的海滩沉积物内部有河床分层，这表明在其发展过程中湖面又上升了三个。因此，普罗沃海滩综合体似乎是在湖水位上升期间建造的，这可以通过连续的山体滑坡沉积导致溢流阈值上升来解释。对海滩高度的评估表明，整个邦纳维尔盆地的两个海滩波峰经历了来自湖泊荷载消除的等效反弹，因此它们是在普罗沃早期发生与邦纳维尔洪水相关的反弹之后形成的。然而，海滩沉积物中收集的腹足动物的放射性碳年龄表明，五个海滩沉积物的序列形成于c.18.1至c.18.1。 17.0 口径ka，邦纳维尔洪水发生在 18 cal 之前。卡。这些年龄与近海沙地内贝壳的先前日期不一致，并引发了关于邦纳维尔湖贝壳放射性碳年龄以及邦纳维尔洪水和普罗沃海岸线年龄的有效性的问题。普罗沃湖最大深度的时间及其与冰消期气候阶段的关系仍未解决。
The Provo shoreline of Lake Bonneville formed following the Bonneville flood, and, based on previous dating, was formed during a period of overflow from about 17.5 to 15.0 cal. ka. In many places the Provo shoreline consists of a pair of distinct shorelines, one ∼3 m higher than the other. We present data from two cuts through double beaches to show that the upper beach is younger and represents sedimentation after a lake‐level rise. In addition, the lower beach deposits are internally stratified by beds that suggest three more lake‐level rises during its development. The Provo beach complex thus appears to have been built during rising lake levels, which can be explained by rises in the overflow threshold by sequential landslide deposition. Evaluation of beach altitudes demonstrates that the two beach crests throughout the Bonneville basin experienced equivalent rebound from removal of the lake load, and therefore they formed after the rebound associated with the Bonneville flood occurred in early Provo time. However, radiocarbon ages on gastropods collected within the beach deposits suggest both that the sequence of five beach deposits formed from c.18.1 to c. 17.0 cal. ka, and that the Bonneville flood occurred before 18 cal. ka. These ages are discordant with previous dates on shells within offshore sands, and raise questions about the validity of radiocarbon ages for shells in Lake Bonneville as well as about the age of the Bonneville flood and Provo shoreline. The timing for maximum Provo lake depths and its association with climate stages during deglaciation remain unresolved.