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

9628549约翰逊在中生代期间，美国太平洋边缘活跃着一条发育良好的大陆岩浆弧，到晚白垩世至第三纪早期，由于伸展坍塌和圣安德烈亚斯变换断裂的发展，该大陆岩浆弧变得支离破碎，并进行了广泛的重新排列。萨利安黑色是这条弧线中央连接的一个错位和突出的碎片。瓜拉拉盆地含有与这种碎裂有关的晚白垩世-早第三纪砾岩，因此提供了一个机会，通过研究盆地鹅卵石和砾岩的亲和力来帮助追踪弧岩的构造块体。这项工作是利用现代同位素分析来建立瓜拉拉盆地鹅卵石与建议的源区之间的岩性和时间联系。所产生的明确关联对于验证现有的这一弧线坍塌和碎裂的几种模型将是有价值的。

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.