Late Neogene stratigraphy and tectonic control on facies evolution in the Laguna Salada Basin, northern Baja California, Mexico
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- 作者：Martí ; n-Barajas ; A. ; Vá ; zquez-Herná ; ndez ; S. ; Carreñ ; o ; A.L. ; Helenes ; J. ; et. al.
- 关键词：Gulf of California ; Stratigraphy ; Neogene ; Laguna Salada ; Salton Trough
- 刊名：Sedimentary Geology
- 出版年：2001
- 出版时间：October 1, 2001
- 年：2001
- 卷：144
- 期：1-2
- 页码：5-35
- 全文大小：1.78 M
文摘
The Laguna Salada Basin (LSB) in northeastern Baja California records late-Neogene marine incursions in the Salton Trough and progradation of the Colorado River delta. Early subsidence and subsequent tectonic erosion are related to evolution of the Sierra El Mayor detachment fault during late Miocene time (<12Ma). The stratigraphy of uplifted blocks on the east-central margin of the Laguna Salada Basin and from three exploratory wells allows reconstruction of the main sedimentary and tectonic events. Marine mudstone and sandstone, and subordinate conglomerate of the Imperial Formation tectonically overlie metamorphic and granitic basement. Microfossils, lithology, and sedimentary structures in the Imperial Formation define Upper Miocene (<6Ma) outer-shelf facies that grade up-section into inner-shelf and tide-dominated delta plain deposits of the ancient Colorado River. Lower Pliocene (
4–2Ma) reddish, sub-arkosic fluvial sandstone and siltstone of the Palm Spring Formation defines progradation of non-marine fluvio-deltaic deposits over the marine Imperial Formation. Continuous outcrops of the Palm Spring are less than 170-m thick, but correlative deposits are more than 570m thick in the lower part of a 2400-m deep geothermal exploratory well on the eastern margin of LSB. Interfingering fluvial-sandstone deposits and prograding alluvial fanglomerates with coarse debris-flow and rock-avalanche deposits crudely mark the onset of vertical slip along the Laguna Salada fault and rapid uplift of Sierra Cucapa and Sierra El Mayor. Up to 2km of Quaternary alluvial-fan and lacustrine deposits accumulated along the eastern margin of LSB, whereas lower subsidence rates produced a thinner sedimentary wedge over a ramp-like crystalline basement along the western margin. In early Pleistocene time (2–1Ma), the Laguna Salada became progressively isolated from the Colorado River delta complex, and the Salton Trough by activity on the Elsinore and Laguna Salada fault zones.
4–2Ma) reddish, sub-arkosic fluvial sandstone and siltstone of the Palm Spring Formation defines progradation of non-marine fluvio-deltaic deposits over the marine Imperial Formation. Continuous outcrops of the Palm Spring are less than 170-m thick, but correlative deposits are more than 570m thick in the lower part of a 2400-m deep geothermal exploratory well on the eastern margin of LSB. Interfingering fluvial-sandstone deposits and prograding alluvial fanglomerates with coarse debris-flow and rock-avalanche deposits crudely mark the onset of vertical slip along the Laguna Salada fault and rapid uplift of Sierra Cucapa and Sierra El Mayor. Up to 2km of Quaternary alluvial-fan and lacustrine deposits accumulated along the eastern margin of LSB, whereas lower subsidence rates produced a thinner sedimentary wedge over a ramp-like crystalline basement along the western margin. In early Pleistocene time (2–1Ma), the Laguna Salada became progressively isolated from the Colorado River delta complex, and the Salton Trough by activity on the Elsinore and Laguna Salada fault zones.