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Marine terrace uplifting rates in the Cantabrian shore:

contribution of U-Th speleothem dating2*Jimnez-Snchez, M.; 1 Stoll, H., 2Giralt, S., 3Aranburu, A. 4 Moreno, A., 1 Domnguez-Cuesta, M.J., 1Mndez-Vicente, A. 1 Ballesteros, D., 1 Pirla, G., 4Valero-arcs, B., R., 5Cheng, H., 5Edwards, L.

1 Department of Geology, University of Oviedo, Arias de Velasco s/n 33005 Spain. * mjimenez@geol.uniovi.es 2 Department of Environmental Geology and Georisks, ICTJA, Sol i Sabaris s/n, E-08028 Barcelona, Spain 3Department of mineralogy and Petrology, University of Basque Country, Sarriena s/n, 48940 Leioa, Spain

INTRODUCTION

arine terraces are wave-cut platform abandoned by the decline

the sea level and/or coast uplift. Speleothems dating fromves situated in marine terraces can contribute to elaborate aodel of coastal evolution because the age of the speleothemsovides a minimum age for the marine terraces. Previoussearch in the Cantabrian Coast (Northern Spain) based on U-Thting of speleothems and cosmogenic nuclides dating ofartzite bedrock indicates uplift rates ranging from 0.03 mm/yr0.19 mm/yr (Jimnez-Snchez et al., 2006; lvarez-Marrn et, 2008). The aim of this study is to present newochronological data obtained in three caves of the Cantabrianast that constrain uplift rates for karstified surfaces identifiedmarine terraces.

4. RESULTS AND DISCUSSIONTable 1 shows the chronological results. These results give a minimum age for the karstic systems and the marine terraces in whichcaves are developed. Maximum rates of uplift were estimated considering four assumptions: 1) speleothem precipitation tookplace in vadose conditions; 2) uplifting took place at a constant rate; 3) during the past 500 ka, the average value of sea levelreached -50 m and prior to 800 ka, reached -25 m (Naish et al., 2009); 4) speleothem ages give minimum values for the ages of theconduits in which they precipitate, while the minimum age of active cave levels is taken as the present time. Considering these

scenarios, maximum rates for marine terraces uplifting range from 0.06 to 0.15 mm/yr (based on cave levels incision) and from0.13 mm/yr to 0.51mm/yr (based on global sea level changes). The first range of values is consistent with uplifting rates obtainedin the West Cantabrian Coast (lvarez-Marrn et al., 2008) with cosmogenic nuclides (0.07-0.15 mm/yr). Also, the ranges of valuesare consistent with the estimated in other marine terraces with U series (e.g. Mediterranean Sea, 0.2-0.4 mm/yr, Dutton et al.,2009) and show lower values than the estimated ones in tectonically uplifting areas (e.g. USA Pacific Coast, 0.15-1.08 mm/yr,Muhs et al., 1992).

. CONCLUSIONS- U-Th dating from speleothems from marinerraces give minimum ages for the marine terraces

nd allows to estimate maximum rates of uplift.- The results shows maximum rates for Cantabrianarine terraces uplifting range from 0.06 to 0.15m/yr, consistent values with previous works in the

rea.

Acknowledgements

This research is a colaboration between several research groups. We are indebted to the projects GRACCIE

(Multidisciplinary research consortium on gradual and abrupt climate changes and their impacts on the environment),

FICYT (Cambio climtico en Asturias: eventos extremos de precipitacin y rgimen hidrolgico en los ltimos 4000 aos)

and Ctedra UNESCO Euskadi Government project entitled Evolucin paleoambiental del Pleistoceno-Holoceno en base a

rellenos krsticos (zona de Urdaibai).

References lvarez-Marrn J, Hetzel R, Niedermann S, Menndez R, Marqunez J (2007) Geomorphology 93(3-4):316-334. Dutton A, Scicchitano G, Monaco C, Desmarchelier J M, Antolioli F et al. (2009) Quaternary Geochronology4, 210 Jimnez-Snchez M, Bischoff J L, Stoll H, Aranburu A (2006) Zur fr Geomorphologie147-129-141. Muhs D R, Rockwell T K, Kennedy G L (1992)Quaternary International, Vol. 15/16, pp. 121-133, 1992. Naish T, Powell R, Levy R, Wilson G, Scherer R, Talarico F, Krissek L, Niessen F, Pompilio M et al. (2009) Nature 458:322-329

SETTINGntabrian shore is an E-W trending coast that represents the south limit of the Bay of Biscayg. 1). This coast is characterized by sea cliffs, short marine terraces (Fig. 2) and a mountain

nge located to the South (Cantabrian Mountain Range). This mountain range was upliftedring the Alpine and shows peaks that exceeded the 2,000 m a.s.l. The three studied caves arecated to the East of Asturias and to the Basque Country (Fig. 1) and are described as follows:

Table 1.- U-Th ages from speleothems samples.

. METHODOLOGYGeomorphological mapping, sketchs and field

bservations were previously made in each cave.Seven samples of speleothems were taken (directmpling and coring) an dated by U-Th with Alpha

pectrometry or ICP-MS in different labs (Table 1).Uplift rates were calculated considering the

elative difference of altitudes between caves and

resent active levels (Fig. 7); estimations based onobal paleo-sea levels (Naish et al. 2009) were alsoade.

stract: New geochronological data obtained in three caves from several marine terraces of the Cantabrian Coast (N Spain) are reported here. Uplift rates based on speleothems U-Th dating weretimated in 0.06-0.15 mm/yr. The results are compared with the obtained ones in other works.

Figure 1.- Situation of the caves of study in the Cantabrian shore.

DRT 2011

Meeting

Oviedo

La Vallina cave (Porra, Asturias), is opened at 70 m a.s.l. (Fig. 3b). The cave shows a NW-SEtrending, 600 m development, and an active level located at 35 m a.s.l.; the karstic massif islimited on top by a surface also interpreted as a marine terrace (90 m a.s.l.). Flowstone levelscovering quartzite sands of fluvial origin can also be recognized (Fig. 5), as well as severalgenerations of speleothems.

El Pindal cave (Ribadedeva, Asturias) is located at 24 m a.s.l. in a karstic massif limited by amarine terrace at 50-64 m a.s.l. (Fig. 3a). The cave shows an E-W trending, 590 m of horizontaldevelopment and the active level located at 6 m a.s.l. The Deva River is interpreted as theformer base level of the cave system. Several quarzitic gravel and sand alluvial levels depositedinside the cave are interpreted as the result of erosion of another marine terrace located to theSouth and carved in quartzite bedrock (150-160 m a.s.l.). Five phases of precipitation ofspeleothems have also been identified; gravity processes, with roof fallen blocks and collapsestructures in cave floor are also remarkable (Fig. 4).

Asnarre cave (Laga, Vizcaya) is located at 20 m a.s.l. (Fig. 3c and 6), developed in a karstic massifalso interpreted as a remnant of a marine terrace (50-60 m), with a horizontal development ofat least 50 m, parallel to the coastline. The first conglomeratic level consists of sandstones andophites clasts deposited by fluviokarstic processes, and fills up more than half of the phreaticconduct. Several cycles of conglomerate and speleothem silted up and fossilized the cave. Noactive level is known at present.

gure 3.- Sketchesfrom the surrounding of a) El Pindal Cave, b) La Vallina Cave and c) Asnarre Cave.

Cave Method/LabSample

ID

Type of

speleothem Age (yr BP)

Reference

level

Inferred Uplift rate (mm/yr)

Cave level

incission

Paleo-sea levels deduced

from Naish et al. (2009)

-50 m -25 m

El Pindal

ICP-MS LABORATORYMinnesota, USA

BANP Stalactite 295,299 12,177Cave active

level at

6 m a.s.l.

0.06 0.25 0.17Core 1 B Flowstone 166,737.3 3,284.7 0.11 0.44 0.29

ALPHA SPECTROMETRYICTJA, Barcelona, Spain

Ceb 1-2 B Flowstone-Core 2 230,011 + 29,484/-23,290 0.08 0.32 0.21Capilla 1 Flowstone-outcrop218,872 +28,256/-22,728 0.08 0.34 0.22Capilla 2 Flowstone-outcrop200,060 +26,326/-21,424 0.09 0.37 0.24

La Vallina ICP-MS LABORATORYMinnesota, USA 100211 Flowstone-outcrop 233,917 19,842 Water tableat 35 m a.s.l. 0.15 0.51 0.32

AsnarreALPHA SPECTROMETRY

Dep. Prehistoire, Muse NationaldHistoire Naturel

Paris, France

LAG0701 Flowstone-outcrop 292 +65/-40

Sea level

- 0.24 0.15

LAG0702Flowstone-outcrop 339 +166/-66 - 0.21 0.13

Flowstonedated

Alluvial sand 10 cm

Figure 5.-

Flowstoneover thealluviandeposits atLa VallinaCave.

Figure 6.-

Entre of theAsnarreCave.

Figure 4.-

Flowstonefrom ElPindalCave.

4Department of Geoenvironmental Processes and Global Change, IPE CSICAvda. Montaana, 1005, 50059 Zaragoza, Spain5Department of Geology and Geophysics, University of Minnesota, Twin Cities, Minneapolis, Minnesota, 55455, U.S.A.

http://www.terra.es/personal2/willow4/llanes_siglo_XXI.jpg

Figure 2.- a) Marine terracesat 50-64 and 125-170 m a.s.l.of El Pindal surrounding. b)Marines terraces at 20-30 and220 m a.s.l. located at the

Eastern of La Vallina (fromwww.rebeliondigital.es ).

a) b)

Figure 6.- Calculate of the uplift rate.