Pedro Val

Department of Earth Sciences

116 Heroy GL


Pedro's CV

PhD Student Earth Sciences
Advisor: Greg Hoke

Research Interests

I study surface/geomorphic processes and the pace at which they act to modify different landscapes. At present, I work on two different projects: one focusing on the mechanisms driving episodic filling and excavation of a piggyback basin in the northern Andean Precordillera; another focusing on the reorganization of a complete drainage network in Central Amazonia.

On the northern end of the Precordillera (San Juan Province, Argentina), the Iglesia basin rides on top of a thin skinned fold and thrust belt that formed some 20 Ma ago. East-verging thrusting is thought to be ongoing, especially on the far eastern end, but deep incision occurs up in the headwaters to west. Here, paleosurfaces are perched some 1500 m above present-day base-level, forming a jaw-dropping low slope surface at 3000 m altitude (Figure 1). Fortunately, extensive paleomagnetic dating was carried by others in the past and provide precise deposition ages of the various units in the foreland basin and also within the Iglesia basin itself (near Angualasto and Rodeo), with reliable accumulation rates. I intend to use cosmogenic isotopes to obtain paleoerosion rates of the last 8 Ma (I hope) of sedimentary record where paleomagnetic data is available and assess wether erosion rates could have been influenced by changes in global climate, or if tectonics was /is the main driver of increased erosion rates in this particular region. While a tectonic signal should be very strong in the foreland (east of the thrust belt), the units within the piggyback basin could bear a climatic signal since this area is deemed to be tectonically quiescent for the past 10 Ma or so.

Picture of Mallory in the field in the Andes

Figure 01: Medano paleosurface at 3100 m altitude. On the far right is a 1.4 m deep profile that Horacio Canelo (field assistant) and I dug in order to sample quartz bearing material for cosmogenic nuclide dating. Hopefully we’ll get a nice surface age here.

Picture of Pedro sitting on the outcrop with the Andes in the background

 In Central Amazonia, extensive and impressive “scars” resembling part of a large drainage network are preserved on the Negro-Solimões interfluve (Figure 2, WNW of Manaus, AM, Brazil). While the paleovalleys indicate a general paleoflow to south, present-day drainage flows north and incise those paleovalleys. It has been suggested by others that this extensive paleonetwork consists of the former course of one of the largest tributaries to the Amazon River, the Rio Negro. My objective is to use cosmogenic nuclides do obtain long-term erosion rates of basins on the right margin of the Rio Negro, as well as in the across-paleonetwork, north-flowing river (Puduari River) to verify whether changes in landscape are ongoing (fast rates), or already stabilized (slow rates). Hopefully, if access allows me to reach a preserved paleo-surface, it should be possible to obtain an age of the abandoned surfaces using beryllium-10 and aluminum-26. Mechanisms behind the network abandonment can be dynamic topography (long-term process related to mantle convection and rise of the Andes), or neotectonism triggered by the same dynamic topography or related to an unknown intraplate faulting mechanism (Caribean vs SA plates?).

Digital Elevation Map of the Amazonia region
Figure 02: Digital Elevation Model of the study area in Amazonia indicating the paleonetwork area marked by very impressive scars on the surface. Inset shows location of study area in South America.



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Department of Earth Sciences
204 Heroy GL
Ph: 315-443-2672
Fx: 315-443-3363

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