Geophysical borehole logging data from Santa Gracia, Chile

Cite as:

Weckmann, Ute; Bauer, Klaus; Krawczyk, Charlotte; Kück, Jochem; Übernickel, Kirstin; von Blanckenburg, Friedhelm (2020): Geophysical borehole logging data from Santa Gracia, Chile. GFZ Data Services. https://doi.org/10.5880/GFZ.2.7.2020.001

Status

I N R E V I E W : Weckmann, Ute; Bauer, Klaus; Krawczyk, Charlotte; Kück, Jochem; Übernickel, Kirstin; von Blanckenburg, Friedhelm (2020): Geophysical borehole logging data from Santa Gracia, Chile. GFZ Data Services. https://doi.org/10.5880/GFZ.2.7.2020.001

Abstract

The DFG funded DeepEarthshape project within the SPP1803 EarthShape (second phase) combines several geoscientific methods and approaches to study the weathering zone in detail in dependence of climate conditions. Projects of the first phase have shown that the weathering zone is much deeper than expected, so that the weathering front was never encountered in the excavated soil pits. At depth of 1 – 2 m appreciable amounts of microbial biomass and DNA counts were encountered. It was further found that bacteria and archaea colonizing rock surfaces are close relatives to those from deeper soil zones. Because we do not know a) the depth of weathering; b) the process advancing it; c) whether this advance is driven by water, gases, and/or biological activity and concentrated along faults; d) whether this zone presents a habitat and interacts with the surface biosphere, we have designed a drilling campaign at all four study sites for joint geochemical, biogeochemical and microbiological exploration and a geophysical campaign for imaging the depth and physical properties of the critical zone. The principle hypotheses of the DeepEarthshape projects are: 1) The advance of the weathering front at depth is a recent process that is linked to climate and coupled with erosion at the surface through a biogeochemical feedback 2) Microbial activity in the deep regolith that advances weathering, is fuelled by young organic matter. The four study sites are distributed along the coast of Chile to have a similar geological setting but different climatic conditions.

Here we present the logging data of the first geophysical borehole survey which took place at Santa Gracia, 40 km NE of La Serena (Coquimbo Region, Chile). The data were acquired on the 2nd of April 2019. The borehole logging was conducted by COMPROBE. The vertical borehole reached down to 87.2 m depth and had a diameter (PQ) of 83.5 mm.

The acoustic televiewer data are freely accessible now in .dlis and PDF formats. The original data files are embargoed until 30 June 2022 and will be accessible via this page afterwards.

Additional Information

The DFG Priority Program 1803 "EarthShape - Earth Surface Shaping by Biota" (2016-2022; https://www.earthshape.net/) explored between scientific disciplines and includes geoscientists and biologists to study from different viewpoints the complex question how microorganisms, animals, and plants influence the shape and development of the Earth’s surface over time scales from the present-day to the young geologic past. All study sites are located in the north-to-south trending Coastal Cordillera mountains of Chile, South America. These sites span from the Atacama Desert in the north to the Araucaria forests approximately 1300 km to the south. The site selection contains a large ecological and climate gradient ranging from very dry to humid climate conditions.

Authors

Weckmann, Ute;GFZ German Research Centre for Geosciences, Potsdam, Germany
Bauer, Klaus;GFZ German Research Centre for Geosciences, Potsdam, Germany
Krawczyk, Charlotte;GFZ German Research Centre for Geosciences, Potsdam, Germany;Technical University Berlin, Institute for Applied Geosciences, Berlin, Germany
Kück, Jochem;GFZ German Research Centre for Geosciences, Potsdam, Germany
Übernickel, Kirstin;University of Tübingen, Tübingen, Germany
von Blanckenburg, Friedhelm;GFZ German Research Centre for Geosciences, Potsdam, Germany

Contact

Weckmann, Ute (Head of research group "Magnetotellurics") ; GFZ German Research Centre for Geosciences, Potsdam, Germany; ➦

Contributors

Araya Vargas, Jaime

Keywords

geophysical borehole logging, televiewer, Full seismic wave fields, electrical resistivity, gamma ray, spontaneous potential, single point resistance, seismic p wave velocities, seismic s-wave velocities, EarthShape, Chile, Coastal Cordillera, Private Reserve Santa Gracia