Nontectonic influences on continental basin-fill sedimenta- tion and post-orogenic sedimentation in a late Cenozoic Extensional Basin

该项目将评估沉积学和地层学 上新世-早更新世圣大卫组 亚利桑那州东南部 圣大卫组沉积在 相对运动几乎停止后的盆岭谷 在山脉前沿和谷底之间 此设置允许 研究中的盆地沉积特征 盆地边缘沿着没有活动变形。 初步研究显示，大约150米厚的 向上变粗的层序， 可变性 在没有活跃的构造作用的情况下， 沉积样式的变化必然是由气候变化引起的 以及与区域排水有关的不断演变的排水模式 一体化 其中一些变化暂时与 海洋古气候记录 该项目代表了第一个 协调一致的努力，以评估沉积学的一个很大程度上前， 重视气候的第四纪陆相盆地充填单元 和古地貌变化，而不是构造作用， 产生沉积物粒度的时空变化 相带分布。 结果将用于a） 表征后期盆地沉积的性质，B） 评估当前假设的有效性， 地层变化，先验，幕式构造作用，和c） 一个上新世-早更新世非冰期的尝试对比 从大陆记录到海洋古气候记录。

The project will evaluate the sedimentology and stratigraphy of the Pliocene-early Pleistocene St. David Formation in southeastern Arizona. The St. David Formation was deposited in a Basin and Range valley after near cessation of relative motion between range fronts and valley floor. This setting allows for examination of the characteristics of basin sedimentation in the absence of active deformation along the basin margins. Preliminary study reveals an approximately 150 m thick coarsening-upward sequence with considerable vertical and lateral variability. In the absence of active tectonism, temporal changes in depositional style must be caused by climatic changes and evolving drainage patterns related to regional drainage integration. Some of these changes are tentatively correlated to marine paleoclimatic records. This project represents the first concerted effort to evaluate the sedimentology of a largely pre- Quaternary continental basin-fill unit with emphasis on climate and paleogeomorphological changes, rather than tectonism, to produce temporal and spatial variations in sediment grain size and facies distribution. The results will be used to a) charactertize the nature of late-stage basin sedimentation, b) evaluate the validity of current hypotheses relating stratigraphic variation, apriori, to episodic tectonism, and c) attempt correlation of a Pliocene-early Pleistocene nonglacial continental record to marine paleoclimatic records.