摘要
Abstract
The famous breached salt anticlines and walls in the northeastern Paradox Basin have previously been considered to bepreexisting diapirs amplified by late Cretaceous to Paleocene Laramide regional compression. Similarly, the spectacular arrays ofnormal faults along the valley sides have been attributed to dissolution of underlying salt. We present evidence that both foldingand normal faulting were a response to NE-directed regional extension during late Eocene to Oligocene, which reactivated thepreexisting NW-trending salt diapirs. Salt diapirs, which grew mainly by sedimentary differential loading during late Paleozoic andMesozoic times, localized the Cenozoic extension within the weak diapirs and their thin roofs, resulting in normal faults above thediapir crests. Faults are cn echelon because extension was oblique to the trend of the preexisting salt structures. Extension createdfanh-slip and rollover anticlines separated by listric normal faults. Where the source layer was thick, diapirs reactively rose belowthe normal faults. Elsewhere, where the source layer was depleted, diapirs subsided as they widened during regional extension.The flanks of tall diapirs subsided, whereas low diapirs entirely subsided. Crestal grabens sank into the widening, subsidingdiapirs, creating cusps of salt. Salt locally extruded over extensionally foundered grabens.关键词
Paradox盆地/盐构造/拉伸活化/下降盐刺穿/断滑褶皱/滚动褶皱/构造地质学Key words
Paradox Basin/ salt structure/ extensional rejuvenation/ falling diapir/ fault-slip fold/ rollover fold/ structural geology分类
天文与地球科学
