Michigan Technological University - Plio-Quaternary kinematics … · 2011. 3. 13. · March 2011 Master of Science in Geological & Mining Eng Sciences To reconstruct the fault kinematics

March 2011 Master of Science in Geological & Mining Eng & Sciences

Plio-Quaternary kinematics and geometry of the Calama-Olacapato-El Toro fault zone across the Puna Plateau, Argentina

A brief overview of my MS Thesis project and INVOGE experience

Federica Lanza

UMB Supervisor: Prof. A. TibaldiAssistant supervisor: Prof. C. Corazzato

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University of Milano-Bicocca - Faculty of Mathematics, Physics and Natural Sciences and

Michigan Technological University – College of Engineering

MTUSupervisor: Prof. G. P. Waite


PURPOSE OF THE WORK

Geological and structural field data were collected along The Calama-Olacapato-El Toro (COT) fault zone, where it crosses the Puna Plateau (Argentina).

Introduction

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San Antonio De

Los Cobres

COT

Structural stations

Fault

After Jordan et al. (1983)


To reconstruct the fault kinematics and the fault geometries through the individuation of striated fault planes and the offset of surface deposits and landforms.

To perform a stress analysis through time by

(I) reconstructing the paleostress tensor using stress-inversion methods

(II) determining stress orientations via study and new calculations of focal mechanisms

To connect faults with recent seismic events and provide information about the seismic risk of the region

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Principal Aims


GEOLOGICAL AND STRUCTURAL SETTING

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The Calama – Olacapato – El Toro Fault Zone (COT)

Transversally crosses the Andean chain and the Puna Plateau at about 24° S.

NW-SE trending left-lateral trascurrent fault system

Can be considered the surface expression of ancient deep crustal trans-lithospheric structures, which have been periodically reactivated

Along with the Archibarca Transverse Zone, the COT is considered a bounding structure of regional importance

From Chernicoff et al. (2002)


Creates favourable tectonic conditions for the locus of mineralizations.

Young volcanic activity (from Miocene to recent times) developed along this fault zone forming an important NW-SE trending volcanic belt constituted by several stratovolcanoes , monogenenitic cones and calderas. E.g: Tugzle, San Jeronimo, Negro De Chorrillos

The Calama – Olacapato – El Toro Fault Zone (COT)

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WHAT I HAVE DONE

Field activities

Interpretation of satellite images

Field surveys:

- Faults measurements (dip direction, dip angle, pitch and kinematic indicators)- Geomorphological observations- Calculation of river offsets and associated slip rates- Logs of paleosismological sections

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Example of paleoseismological section

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Fault gauge, pebble and boulder alignments

High density of fractures and secondary faults

Faulting occurred during multiple events with surface ruptures


First Assumptions from structural data, and measurements collected in the field

The surface trace is rectilinear suggesting a vertical dip at least in the uppermost crust.

Considering the kinematics, a vertical component is usually present in the form of relative uplift of the northeastern tectonic block.

In the Chilean region, field evidence of Plio-Quaternary motions disappears and so the COT lineament should be older there.

Open fissures are only partially filled and are not located along or close to slopes. They might be interpreted as evidence of prehistoric/historic surface faulting.

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Faults offset Pliocene or Pleistocene volcanic deposits suggesting a Plio-Quaternary activity of the Puna Plateau segment of the COT fault zone.


N=12

MP=

66.67%

4

N=6

MP=

83.33%

5

N=9

MP=

44.44%

6

N=7

MP=

71.43%

7

N=6

MP=

50%

22

10

MP=

100%

N=3

11

MP=

50%

N=6

19

MP=

100%

N=5

98

MP=

60%

N=5 N=8

MP=

50% MP=

100%

N=3

107 108 60

MP=

60%

N=5

21

MP=

57.14

%

N=7 N=7

MP=

42.86

% 28

N=23

MP=

52.17

%

N=19

MP=

47.37

%

W

E

82-104-105-

106

N=6

MP=

83.33%

30

First Results from Initial Processing: fault geometry as obtained by rose diagrams

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457

6

22

10

11

19

98 107

108

60 21 28

30

82-104-105-

106

E

W

Direction of

compression

Direction of

extensionσ1 σ2 σ3

Stress Analysis (I): results from numerical inversion of striated fault planes

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456722

10

11

19

98 107 108 60 21 28

W

E

82-104-105-

106

30

Compressive Tensile

Fault Plane Solutions: Right Dihedra Method of Angelier and Mechler (1977)

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WHAT IS LEFT TO DO

Project developement

Stress Analysis (II)

- calculation of focal mechanisms in order to compare them to those derived from the inversion of striated fault planes

Research in seismic catalogs (CERESIS and IRIS) about the seismicity of the area in order to connect faults with recent seismic events and to provide information about the seismic risk of the region

Expected date of finishing: end of this summer (August 26th 2011)

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Coursework and acquired skills

How to write a research paper

How to write a review paper

Interpret seismic signals fromvolcanoes, how to use MATLAB

Chance to learn physicalvolcanology and interpret volcanodeposits.

Field methods and seismic data processing

Volcanology

Global Geophysics and Geotectonics

Volcano Seismology (currently enrolled)

Research project

Volcanology Field trip to New Mexico (as Special Topic in Geology)

IRIS/PASSCAL Instrument Center and EarthScope USArray Array Operations Facility summer student internship at New Mexico Tech.

THE OVERALL INVOGE EXPERIENCE

… and what will happen before I leave for Italy

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Highlights

Unique courses

Unique opportunities

Increase effectiveness by different learning approach

Implementation of new tools

Improve organizational competence

Development of personal skills

Inspiring, creative, and cosmopolitan environment

American culture

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Questions?

Thank you!

Documents

Michigan Technological University - Plio-Quaternary kinematics … · 2011. 3. 13. · March 2011 Master of Science in Geological & Mining Eng Sciences To reconstruct the fault kinematics