Skip to Main Content
Book Chapter

The magnetism in tectonically controlled travertine as a palaeoseismological tool: Examples from the Sıcak Çermik geothermal field, central Turkey

By
H. Gürsoy
H. Gürsoy
Department of Geology, Cumhuriyet University, 58140 Sivas, Turkey (e-mail: gursoy@cumhuriyet.edu.tr)
Search for other works by this author on:
B. L. Mesci
B. L. Mesci
Department of Geology, Cumhuriyet University, 58140 Sivas, Turkey (e-mail: gursoy@cumhuriyet.edu.tr)
Search for other works by this author on:
J. D. A. Piper
J. D. A. Piper
Geomagnetism Laboratory, Department of Earth and Ocean Sciences, University of Liverpool, Liverpool L69 7ZE, UK
Search for other works by this author on:
O. Tatar
O. Tatar
Department of Geology, Cumhuriyet University, 58140 Sivas, Turkey (e-mail: gursoy@cumhuriyet.edu.tr)
Search for other works by this author on:
C. J. Davies
C. J. Davies
Geomagnetism Laboratory, Department of Earth and Ocean Sciences, University of Liverpool, Liverpool L69 7ZE, UK
Search for other works by this author on:
Published:
January 01, 2007

Abstract

In regions of neotectonic activity geothermal waters flow into extensional fissures and deposit successive layers of carbonate as fissure travertine incorporating small amounts of ferromagnetic grains. The same waters spill out onto the surface to deposit bedded travertine, which may also incorporate wind-blown dust with a ferromagnetic component. Travertine deposits are linked to earthquake activity because geothermal reservoirs are reset and activated by earthquake fracturing but tend to become sealed by deposition of carbonate between events. A weak ferromagnetism records the ambient field at the time of deposition and sequential deposition can identify cycles of secular variation of the geomagnetic field to provide a means of estimating the rate of travertine growth. The palaeomagnetic record in three travertine fissures from the Sıcak Çermik geothermal field in central Anatolia dated to between 100 and 360 ka by U–Th determinations has been examined to relate the geomagnetic signature to earthquake-induced layering. Sequential sampling from the margins (earliest deposition) to the centres (last deposition) identifies directional migrations reminiscent of geomagnetic secular variation. On the assumption that these cycles record time periods of 1–2 ka, the number of travertine layers identifies resetting of the geothermal system by earthquakes every 50–100 years. Travertine precipitation occurs at rates of 0.1–0.3 mm a−1 on each side of the extensional fissures and at a rate an order higher than for bedded travertine on the surface. Earthquakes of magnitude M≤4 occur too frequently in the Sivas Basin to have any apparent influence on travertine deposition but earthquakes with M in the range 4.5–5.5 occur with a frequency compatible with the travertine layering, and it appears to be events of this order that are recorded by sequential travertine deposition. Two signatures of much larger earthquakes on a 1–10 ka time scale are also present in the travertine deposition: (1) the incidental emplacement of massive travertine or fracturing of earlier travertine without destruction of the fissure as a site of travertine emplacement; (2) termination of the fissure as a site of deposition with transfer of the geothermal activity to a new fracture. The presence of some 25 fractures in the c. 300 ka Sıcak Çermik field growing at rates of 0.1–0.6 mm a−1 suggests that the type (2) signature may be achieved by an M c. 7.5 event approximately every 10 ka.

You do not currently have access to this article.

Figures & Tables

Contents

Geological Society, London, Special Publications

The Geodynamics of the Aegean and Anatolia

T. Taymaz
T. Taymaz
Istanbul Technical University, Turkey
Search for other works by this author on:
Y. Yilmaz
Y. Yilmaz
Kadir Has University, Istanbul, Turkey
Search for other works by this author on:
Y. Dilek
Y. Dilek
Miami University, Ohio, USA
Search for other works by this author on:
Geological Society of London
Volume
291
ISBN electronic:
9781862395398
Publication date:
January 01, 2007

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal