A flexural model for the Paradox Basin: implications for the tectonics of the Ancestral Rocky Mountains
A flexural model for the Paradox Basin: implications for the tectonics of the Ancestral Rocky Mountains
复制标题
悖论盆地的弯曲模型：对祖先落基山脉构造的影响
DOI：
10.1046/j.1365-2117.2003.00194.x
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发表时间：
2003
期刊：
影响因子：
3.2
通讯作者：
D. Barbeau
中科院分区：
文献类型：
--
作者：
D. Barbeau
Paradox盆地是美国科罗拉多州犹他州在宾夕法尼亚-二叠纪原始落基山(ARM)造山事件期间沿着基底参与的不压实隆起西南侧发育的一个大型(190公里×265公里)不对称盆地。以前被解释为拉分盆地，Paradox盆地更类似于前陆内挠曲盆地，如那些在晚期以基底为核心的隆起之间发育的盆地
美国西部内陆白垩纪-始新世拉莱米德造山作用。不相容-悖论系统的形态、沉降史、相结构和构造关系是典型的静止前陆盆地系统的典范。沿着西南向的逆冲冲断，约5公里的粗粒同构造Desmoinesian-WolfCampiao(宾夕法尼亚中期至早二叠世；-310-260 Ma)的沉积物被冲积扇从不压实隆起中剥离出来，并被悖论盆地近端的风成改造的河流巨型扇沉积所改造。不压实锋西南200 km处隆起-平行屏障的同时代隆起限制了盆地南部和西部开阔大洋的回流，并促进了盆地中部和远洋部分厚重的蒸发岩-页岩和生物礁碳酸盐相的沉积。近岸碳酸盐浅滩和陆相硅质碎屑沉积在盆地下沉后期溢流
密苏里到沃尔夫坎皮亚(-300-260 Ma)，因为沉积物通量超过了可容纳空间的生成速度。根据地震、钻孔和露头资料重建的二叠纪末期二维盆地剖面描绘了这些沉积系统与宾夕法尼亚-二叠纪沉降产生的差异可容空间的关系，突出了Paradox盆地充填与其他古代和现代前陆盆地的相似之处。恢复的盆地剖面的弯曲模拟表明，悖论盆地可以用模式不压实隆起和伴生的同生沉积对完全破碎的陆壳进行挠曲加载来描述。ARM的其他逆冲盆地具有与Paradox盆地相似的盆地剖面和相结构，表明许多ARM盆地可能具有挠曲地球动力学机制。因此，试图解释ARM隆起发展的板块构造模型需要包含一个广泛生成挠曲盆地的机制。
The Paradox Basin is a large (l90km x 265 km) asymmetric basin that developed along the southwestern flank of the basement-involved Uncompahgre uplift in Utah aod Colorado, USA during the Pennsylvaoian-Permian Ancestral Rocky Mountain (ARM) orogenic event. Previously interpreted as a pull-apart basin, the Paradox Basin more closely resembles intraforeland flexural basins such as those that developed between the basement-cored uplifts of the Late
Cretaceous-Eocene Laramide orogeny in the western interior USA. The shape, subsidence history, facies architecture, and structural relationships of the Uncompahgre-Paradox system are exemplary of typical \\\'immobile\\\' foreland basin systems. Along the southwest-vergent Uncompahgre thrust, ~ 5km of coarse-grained syntectonic Desmoinesian-Wolfcampiao (mid-Pennsylvaniao to early Permian; -310-260 Ma) sediments were shed from the Uncompahgre uplift by alluvial fans and reworked by aeolian-modified fluvial megafan deposystems in the proximal Paradox Basin. The coeval rise of an uplift-parallel barrier -200 km southwest of the Uncompahgre front restricted reflux from the open ocean south and west of the basin, and promoted deposition of thick evaporite-shale and biohermal carbonate facies in the medial and distal submarine parts of the basin, respectively. Nearshore carbonate shoal and terrestrial siliciclastic deposystems overtopped the basin during the late stages of subsidence during
the Missourian through Wolfcampian (-300-260 Ma) as sediment flux outpaced the rate of generation of accommodation space. Reconstruction of an end-Permian two-dimensional basin profile from seismic, borehole, and outcrop data depicts the relationship of these deposystems to the differential accommodation space generated by Pennsylvanian-Permian subsidence, highlighting the similarities between the Paradox basin-fill and that of other ancient and modern foreland basins. Flexural modeling of the restored basin profile indicates that the Paradox Basin can be described by flexural loading of a fully broken continental crust by a model Uncompahgre uplift and accompanying synorogenic sediments. Other thrust-bounded basins of the ARM have similar basin profiles and facies architectures to those of the Paradox Basin, suggesting that many ARM basins may share a flexural geodynamic mechanism. Therefore, plate tectonic models that attempt to explain the development of ARM uplifts need to incorporate a mechanism for the widespread generation of flexural basins.