Chemical and Isotopic Composition of Late-Cretaceous and Early Tertiary Conglomerates, Western California: Constraints on Paleogeography

9628549约翰逊 在中生代，一个发育良好的大陆岩浆弧沿着美国太平洋边缘活动，在晚白垩世至早第三纪时期，由于伸展塌陷和圣安德烈亚斯转换断层的发展，这些岩石变得支离破碎并广泛重新排列。Salinian Black是这个弧的中心环节的一个移位的和独特的片段。瓜拉拉盆地包含与这种破碎有关的晚白垩世-早第三纪砾岩，因此提供了通过检查盆地鹅卵石和砾岩的亲和力来帮助追踪弧形岩石构造块的机会。这项工作是利用现代同位素分析来建立瓜拉拉盆地的鹅卵石和建议的源岩之间的岩性和时间联系。所产生的连续相关性对于在现存的几种弧的坍塌和碎裂模型之间进行对比是有价值的。

9628549 Johnson During the Mesozoic a well developed continental magmatic arc was active along the Pacific margin of the U.S., which by late Cretaceous to early tertiary time became fragmented and extensively rearranged by the development of extensional collapse and San Andreas transform faulting. The Salinian Black is a displaced and distinded fragment of the central link of this arc. The Gualala Basin contains late cretaceous -early tertiary conglomerates related to this fragmentation, thus provides an opportunity to help track tectonic blocks of arc rocks by examining affinities of the basin's cobbles and conglomerates. This work is to use modern isotopic analysis to establish lithologic and temporal links between cobbles in the Gualala Basin and proposal source terranes. Definitive correlation's produced would be valuable in dueriminating between the several extant models for the collapse and fragmentation of this arc.