کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6431353 | 1635157 | 2014 | 26 صفحه PDF | دانلود رایگان |
- Study the sequential stratigraphic analysis of the Los Colorados Formation.
- We clarified the contacts between the units that compose the Group Payogastilla and its hierarchy.
- Tectonic effects have controlled the evolution and characteristics of the basin.
- The changes in the paleoenvironment of the Payogastilla Group are consequence of the tectonic and accommodation space.
The stratigraphic and sedimentological characteristics of the Payogastilla Group represent important tectono-sedimentary constraints on the evolution of the Andean foreland basin in northwestern Argentina. This nonmarine unit unconformably rests on top of the post-rift deposits of the middle Eocene Lumbrera Formation of the Santa Bárbara Subgroup (Salta Group). Eocene-Pliocene paleoenvironmental changes are a direct result of the tectonic settings and accommodation space. Sequential stratigraphic analysis of the paleoenvironment of the Los Colorados Formation strata indicates the presence of three third-order sequences. Each sequence comprises a low-accommodation systems tract (LAST) and a high-accommodation systems tract (HAST). Substantial tectonic activity from the middle to upper Miocene is represented by Angastaco Formation strata that contain a shallow, gravel-braided fluvial system associated with gravity flows, with thicknesses of 4550 m (Calchaquà River) to 1500 m (Tonco). This activity marked the depocenter of the Angastaco basin. The development of a basal unconformity and the erosion of the Los Colorados Formation suggest a renewed uplift of the source area. Changes in the fluvial systems indicate an increase of the accommodation space.To obtain better temporal constraints on the basin evolution, new U-Pb ages on zircons from five pyroclastic airfall and two sedimentary levels were determined. A substantial environmental change in the upper Miocene (10-5 Ma) is associated with three episodes of tectonic uplift that are reflected in variations in the sedimentation rates of the Palo Pintado Formation. A reactivated Pliocene tectonic uplift is recorded in alluvial fans that originated from the east.
Journal: Journal of South American Earth Sciences - Volume 52, July 2014, Pages 234-259