Seismic Analysis and Basin History of

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Feb 22, 2014 (3 years and 8 months ago)

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Seismic Analysis and Basin History of
Lake Titicaca, Peru and Bolivia

Colby A. Smith

Department of Geology

University of Cincinnati

Cincinnati, OH

South American Monsoon



During the austral summer the inter
-

tropical convergence zone (ITCZ)

moves south over the northern Altiplano.










During the austral winter the ITCZ moves

north of the equator and little or no

precipitation reaches the Altiplano.



delta 1 at 341 ms

delta 2 at 303 ms

1

2

Lower Deltas: Boomer Only

delta 2 at 298 ms

delta 3 at 242 ms

Delta 2 appears in both data sets

delta 3 at 242 ms

delta 4 at 122 ms

Upper Deltas: Air Gun Only

Other Features of Interest:

Diapirs

LT01
-
2B Density Data

LT01
-
2B TOC Data

Lowstand Deltas

Delta
Number

ms BLL

m BLL

Maximum Age
YBP

Delta 4

122

125

102,000

Delta 3

242

182

132,000

Delta 2

303

227

154,000

Delta 1

341

256

248,000

60 m isobaths in blue were used to construct the curves.

(D’Agostino et al., 2002)


Deltas in red are at depths of 125,182, 227, 256 m BLL.


Initial Porosity 0.75

Porosity Gradient
-
1.77 km
-
1

(Fritz et al., in prep.)




Holocene Sedimentation Rate 0.2 mm yr
-
1

Last Glacial Sedimentation Rate 0.6 mm yr
-
1

(Seltzer et al., 2002)

Weighted Mean Sedimentation Rate 0.5 mm yr
-
1




Approximately 600 m of sediment in
Copacabana Bay decompacts to 1142 m.


Maximum Age
5710 ka


Minimum Age 1903
ka

Weighted Mean Age 2260 ka

The Age of Lake Titicaca

Conclusions


Four lowstand sediment packages each including a delta were
interpreted from seismic data obtained in or near Copacabana
Bay on the west side of Lake Titicaca. Maximum ages for these
deltas range from 125 ka to 256 ka BP



A study of the modern bathymetry of Lake Titicaca along with
the seismic data showing paleo
-
deltas suggests that
sedimentation is out pacing subsidence of the basin.



Seismic data to bedrock were used in conjunction with
sedimentation rates from Copacabana Bay to estimate the age
of Lake Titicaca to between 5710 ka and 1903 ka BP with a
weighted mean age of 2260 ka BP.


C. A. Scholz,


Departement of Earth Sciences, Syracuse University, Syracuse, NY


P. A. Baker,


Division of Earth of and Ocean Sciences, Duke Univerisity, Durham, NC


S. C. Fritz,


Department of Geosciences University of Nebraska, Lincoln, NE


P. Cataneo,


Departement of Earth Sciences, Syracuse University, Syracuse, NY


Acknowledgements