TY - JOUR
T1 - Identifying past earthquakes on carbonate faults
T2 - Advances and limitations of the 'Rare Earth Element' method based on analysis of the Spili Fault, Crete, Greece
AU - Mouslopoulou, Vasiliki
AU - Moraetis, Daniel
AU - Fassoulas, Charalambos
N1 - Funding Information:
This research was supported by a post-doctoral Marie Curie International Incoming Fellowship to V. Mouslopoulou (within the 7th European Community Framework Programme under contract no. PIIF-GA-2009-235931 ). Useful communication with A. Schlagenhauf, I. Manighetti and E. Boucher is gratefully acknowledged. G. Iliopoulos and N. Mouslopoulos are thanked for assistance during fieldwork and core crushing, respectively. N. Nikolaidis is thanked for providing access to the ICP-MS whereas A. Androulaki and L. Saru are thanked for effectively pursuing the ICP measurements. J. Begg is gratefully acknowledged for a thorough review and for numerous constructive comments and discussions that improved this work. Last but not least, D. Hristopulos is thanked for providing constant support and encouragement towards the successful completion of this study. Two anonymous reviewers and the Editor (Dr Y. Ricard) are gratefully acknowledged for constructive comments that improved this study.
PY - 2011/9/1
Y1 - 2011/9/1
N2 - Recent work (Carcaillet et al., 2008; Manighetti et al., 2010) has utilised a well-established earthquake record on a normal fault in Italy (the Magnola Fault) to successfully test a new method for identifying paleoearthquakes on carbonate rocks: that of chemical analysis of their exhumed fault planes. Here we take the next natural step, applying this novel method on a notionally active normal fault in Greece, the Spili Fault, for which no paleoearthquake record exists. Despite the 'blind' sampling, data reveal an outstanding record of systematic fluctuations in the concentrations of Rare Earth Elements (REE) and Yttrium (Y) upscarp, which closely resemble those recorded on the Magnola Fault. Chemical analysis of 35 core-samples extracted from a 10. m high section of the exhumed Spili Fault plane records upscarp depletion in the REE-Y concentrations at an average rate of ca. 9.3%/m. Depletion is overprinted by locally increased REE-Y concentrations upscarp. A minimum of four such concentration fluctuations, with wavelengths ranging from 0.5 to 3. m, are recorded. Each fluctuation is interpreted to be generated by at least one paleoearthquake that episodically exhumed a zone of the fault plane. Each zone consists of an upper domain that is enriched in REE-Y and a lower un-enriched domain. REE-Y enrichment is due to the prolonged (at least few 100's of years) contact of the limestone with the soil, whereas the un-enriched domain reflects instantaneous uplift from depths greater than the base of the soil, during the same earthquake. The REE-Y analytical method cannot resolve individual small-sized earthquakes (with slip less than the thickness of the soil-cover) and/or individual large- and small-sized earthquakes which are clustered in time (repeat time< 100's. yr). It may therefore yield better results when applied on large (≥ 20. km) carbonate faults that rupture the earth's crust at most once every ca. 0.5. kyr; nevertheless the number of identified earthquakes should always be treated as a minimum.
AB - Recent work (Carcaillet et al., 2008; Manighetti et al., 2010) has utilised a well-established earthquake record on a normal fault in Italy (the Magnola Fault) to successfully test a new method for identifying paleoearthquakes on carbonate rocks: that of chemical analysis of their exhumed fault planes. Here we take the next natural step, applying this novel method on a notionally active normal fault in Greece, the Spili Fault, for which no paleoearthquake record exists. Despite the 'blind' sampling, data reveal an outstanding record of systematic fluctuations in the concentrations of Rare Earth Elements (REE) and Yttrium (Y) upscarp, which closely resemble those recorded on the Magnola Fault. Chemical analysis of 35 core-samples extracted from a 10. m high section of the exhumed Spili Fault plane records upscarp depletion in the REE-Y concentrations at an average rate of ca. 9.3%/m. Depletion is overprinted by locally increased REE-Y concentrations upscarp. A minimum of four such concentration fluctuations, with wavelengths ranging from 0.5 to 3. m, are recorded. Each fluctuation is interpreted to be generated by at least one paleoearthquake that episodically exhumed a zone of the fault plane. Each zone consists of an upper domain that is enriched in REE-Y and a lower un-enriched domain. REE-Y enrichment is due to the prolonged (at least few 100's of years) contact of the limestone with the soil, whereas the un-enriched domain reflects instantaneous uplift from depths greater than the base of the soil, during the same earthquake. The REE-Y analytical method cannot resolve individual small-sized earthquakes (with slip less than the thickness of the soil-cover) and/or individual large- and small-sized earthquakes which are clustered in time (repeat time< 100's. yr). It may therefore yield better results when applied on large (≥ 20. km) carbonate faults that rupture the earth's crust at most once every ca. 0.5. kyr; nevertheless the number of identified earthquakes should always be treated as a minimum.
KW - Carbonate scarp
KW - Crete
KW - Normal fault
KW - Paleoearthquake
KW - Rare earth elements
KW - Soil
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U2 - 10.1016/j.epsl.2011.06.015
DO - 10.1016/j.epsl.2011.06.015
M3 - Article
AN - SCOPUS:79961128557
SN - 0012-821X
VL - 309
SP - 45
EP - 55
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
IS - 1-2
ER -