NSF Org:	EAR Division Of Earth Sciences
Recipient:	TRUSTEES OF INDIANA UNIVERSITY
Initial Amendment Date:	July 7, 2014
Latest Amendment Date:	July 7, 2014
Award Number:	1445649
Award Instrument:	Standard Grant
Program Manager:	Justin Lawrence jlawrenc@nsf.gov  (703)292-2425 EAR  Division Of Earth Sciences GEO  Directorate for Geosciences
Start Date:	April 1, 2015
End Date:	March 31, 2016 (Estimated)
Total Intended Award Amount:	$53,151.00
Total Awarded Amount to Date:	$53,151.00
Funds Obligated to Date:	FY 2014 = $53,151.00
History of Investigator:	Broxton Bird (Principal Investigator) bwbird@iu.edu
Recipient Sponsored Research Office:	Indiana University 107 S INDIANA AVE BLOOMINGTON IN  US  47405-7000 (317)278-3473
Sponsor Congressional District:	09
Primary Place of Performance:	Indiana University Purdue University Indianapolis 980 Indiana Avenue, Room 2232 Indianapolis IN  US  46202-2915
Primary Place of Performance Congressional District:	07
Unique Entity Identifier (UEI):	YH86RTW2YVJ4
Parent UEI:
NSF Program(s):	GLOBAL CHANGE
Primary Program Source:	01001415DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s):	1304, 7916, EGCH
Program Element Code(s):	157700
Award Agency Code:	4900
Fund Agency Code:	4900
Assistance Listing Number(s):	47.050

ABSTRACT

The proposed work would conduct a detailed geophysical survey of the Laguna de Tota, a large tectonic lake in the Eastern Cordillera of the Colombian Andes. The survey would determine the thickness and layout of the bottom sediment layers, and allow the researchers to better understand the type of materials available for a possible later expedition to extract samples by drilling for cores. The proposed geophysical work involves an international team of U.S. and Colombian geoscientists, which will strengthen international collaboration and provide training for U.S. and Colombian graduate students. Drs. Bird and Escobar will engage local communities that rely on Tota's water resources by giving lectures about the geophysical and drilling project at community centers. They will also speak at Colombian universities to increase awareness about Andean water resources and climate change.

The location of the lake is important, because as South America's third largest lake, it is well removed to the North from the other two (Lakes Titicaca and Junin, in Bolivia and Peru). A sediment core from the Laguna de Tota could potentially contain climate data recording temperatures and lake process history over the last several hundred thousand years, and include several glacial/inter-glacial climate signals, including that of the South American Summer Monsoon, whose details are poorly understood.

Using a small, high-resolution single-channel airgun seismic reflection system and a CHIRP sub-bottom profiler the team would map Tota's bathymetry, determine the thickness of lacustrine sedimentary sequences, locate depositional centers and identify lake-level transgression-regression sequences. Littoral sediment cores collected from Tota in 2013 suggest that the lake's sediment archive contains detailed climatic information, including evidence of past lake level changes. The team would characterize Tota's sediment archive and assess its potential for developing a long-term paleoclimate record. Despite near certainty that Tota's sediment archive spans at least several hundred thousand years, no known geophysical or paleoclimate work has been conducted on the lake previously. The proposed work therefore represents a unique opportunity to investigate a site that has tremendous potential for containing a long, continuous record of Northern Hemisphere South American Pleistocene climate. This work is in its initial phases, but has potential to transform our understanding of tropical climate change. As such, this work is appropriate for the EAGER funding mechanism that is designed to support "high risk-high pay off" exploratory work in its early stages.

The funding is requested for ¾ of a summer month for the lead PI, 1 month for his graduate student, as well as travel for 3 PIs and 2 U.S. graduate students. Airfreight for the coring equipment from LacCore and its return, per diem in the Tota vicinity, and boat and truck rental are also requested.

PROJECT OUTCOMES REPORT

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

Lago de Tota is one of the largest of the tectonic basins in the Eastern Cordillera of the Colombian Andes and the largest lake in the northern Andes. The lake has been recognized by the paleoclimate community as having great potential for advancing our understanding of the global climate system and identified as a priority for deep lake drilling. Determining the physical and spatial characteristics of the sediment package contained within Tota is an essential and critical step toward developing a deep lake drilling project that would ultimately produce a long, continuous paleoclimate record from the Northern Hemisphere Andes.

 

This award funded the acquisition of geophysical data that will be used to identify the location of future drilling activities and ultimately allow the most complete and longest sediment sequence to be collected from Tota. Because this paleoclimate archive would likely extend from the present day sediment water interface through the Pleistocene, paleoclimate proxies would be able to be calibrated to a modern understanding of the relationships between lake processes and climate.

 

Over the course of a week, over 82.5 km of data were acquired. Two different seismic datasets were collected simultaneously during the study:

 

1. A single-channel seismic reflection survey of the lake basin using a small airgun source. This survey was used to image the complete sedimentary fill of the basin;
2. A high-resolution survey of the near-surface section (z < 20 m) using a CHIRP sub-bottom profiler.

 

The collected data indicate that:

1. The lake basin is partitioned into a series of sub-basins bounded by steeply inclined faults.
2. The sediment package filling these basins are typically asymmetrically developed.
3. Reflections associated with the sediment package span more than 400 ms, suggesting that the sediment package is probably over 300 m thick.
4. In general, the upper portion of the basin fill is composed of moderate to high amplitude reflections that are locally continuous. The CHIRP sections document localized truncation of surfaces that indicate lake level has fluctuated in the past.
5. Reflection amplitude becomes weaker and more discontinuous in the deeper portions of the basin.
6. Locally the reflections of the sedimentary package appear contorted and chaotically organized. These are interpreted to be debris flows associated with reactivation of the many faults that border the basin. Debris flows appear more frequently in the northern sub-basin.
7. Displacement of near surface reflections is interpreted as evidence that the basin continues to seismically active.

 

The geophysical work funded by this award, involved an international team of US and Colombian geoscientists, strengthening international collaboration between these countries. Graduate students from the US and Colombia were involved in the fieldwork, fostering capacity building for Colombian geoscience students and providing the US graduate students with international research experience.

 

Last Modified: 07/13/2016
Modified by: Broxton W Bird

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