Geologia Sudetica, 2014, 42: 188–189.
Tec tonic geomorphometric stud ies in the sur round ings of Rechnitz tec tonic win dow, East ern Alps
Gábor Kovács1,2,3, Tamás Telbisz4, Balázs Székely1,5,6 & Zsófia Koma1
1 De part ment of Geo phys ics and Space Sci ences, Eötvös Loránd Uni ver sity, 1/C Pázmány P. str, H-1117 Bu da pest, Hun gary, e-mail:
skovacsgabor@caesar.elte.hu
2 De part ment of Ge ol ogy, Uni ver sity of West Hun gary, 4. Károlyi Gáspár tér, H-9700 Szombathely, Hun gary
3 Geomega Ltd. 4. Mester utca, H-1095 Bu da pest, Hun gary
4 De part ment of Phys i cal Ge og ra phy, Eötvös Loránd Uni ver sity, 1/C Pázmány P. sétány, H-1117 Bu da pest, Hun gary
5 Interdisziplinäres Ökologisches Zentrum, TU Bergakademie Freiberg, Leipziger Str. 29, 09596 Freiberg, Ger many
6 Re search Group Photo gram metry, De part ment of Ge od esy and Geoinformation, Vi enna Uni ver sity of Tech nol ogy, Gusshausstr.
27-29/E120.7, A-1040 Vi enna, Aus tria
The var i ous el e ments of geomorphometric toolkit of sur face anal y sis, proved to be use ful in tec tonic geo mor - phol ogy (Marple & Talwani 2000; Keller & Pinter 2002) have been ap plied to ana lyse our study area sit u ated be - tween the still up lift ing East ern Alps and the sub sid ing Dan - ube Ba sin. (For de tailed de scrip tion of the study area see Kovács, in this vol ume). In this pa per, we stud ied young (Late Mio cene) de for ma tions that ex hibit ver ti cally small scale top o graphic vari a tions and ver ti cal dis place ments.
These are hardly ob serv able in ex ist ing in dus trial seis mic sec tions due to the low (~30 m) ver ti cal res o lu tion. Fur ther on, ex ist ing seis mic pro files ex plore only some parts of the study area. Rock out crops are scarce due to the in tense veg - e ta tion. Even a qual i ta tive vi sual com par i son may re veal dif fer ences among parts of the study area, how ever Dig i tal El e va tion Model (DEM) based geomorphometry is re quired for an in-depth study of these dif fer ences.
DEM was an a lyzed in or der to com pare sub units of the area. Av er age el e va tion, gen eral tilt of the en ve lope sur face, slope and as pect dis tri bu tions proved to be very ef fi cient in
this anal y sis (Fig. 1). These meth ods re vealed sig nif i cant dif fer ences among sub units that are partly caused by tec ton - ics. Top o graphic swath pro file anal y sis is con sid ered to be an im proved, DEM-based ver sion of tra di tional cross-sec - tion anal y sis. To avoid ar bi trari ness of sim ple line pro files, the swath method hor i zon tally ex pands the cross sec tion line into a rect an gu lar swath. Com monly, pro file Z val ues are cal cu lated as sta tis ti cal pa ram e ters (min i mum, mean, max i mum, etc.) of el e va tion val ues be ing at the same dis - tance from the base line of the swath (Telbisz et al., 2013).
Top o graphic swath anal y ses ap plied for the sur face and for Pleis to cene gravel ter races dis tinctly, re vealed the post-sed - i ment tilt ing of dif fer ent blocks (Telbisz et al., 2013; Ko- vács & Telbisz, 2013). A ro bust DEM seg men ta tion method has been de vel oped by Székely et al. (in re view) for var i ous geoscientific ap pli ca tions. The al go rithm takes DEM pix els as a point cloud as in put and is search ing for pla nar fea tures that ful fill cer tain cri te ria con trolled by user-de fined pa ram - e ters (num ber of points to cal cu late lo cal nor mal vec tors, point-to-plane dis tance, an gu lar tol er ance, etc.). Al though the seg men ta tion is of ten sen si tive to the ini tial pa ram e ters, in many cases many fit ted planes are sta ble. Many planes tend to out line geomorphic fea tures of the study area and there fore they are suit able for fur ther geomorphometric anal y sis.
River style in ves ti ga tion (RSI) is a widely used method (Holbrook & Schumm, 1999; Keller & Pinter, 2002; Marple
& Talwani, 2002) proved to be ef fi cient in neotectonic in - ves ti ga tion ap plied to dif fer ent parts of the Pannonian Ba sin (Petrovszki & Timár, 2010; Zámolyi et al., 2010; Gál et al., 2010; Petrovszki et al., 2012). Sin u os ity cal cu la tion of me - an der ing seg ments is a fre quently used com po nent of RSI.
In our study, it was com ple mented with the iden ti fi ca tion of other river styles such as straight, in cised, anastomosing and braided ones. Rivers rap idly, and more im por tantly, very sen si tively re act to even small slope changes of the val ley floor by switch ing their river style. As river gra di ent incre- ases, the pat tern may be come more sin u ous or even braided, whereas de creas ing gra di ent seg ments be come less sin u ous, straight or anastomosing. Thus, these changes are re flected in the mor phol ogy (Ouchi, 1985). In the to tally flat south - east ern area streams turn left sharply in some cases where as pect map sug gest gen tle fold ing. River style in that cases
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CETeG 2014 AB STRACTSFig. 1. Dif fer ences of mode of slope in the study area with the de - lin eated sub units. Ac cu racy is 1°, win dow size 1000 m. For lo ca - tion see the in set.
re flect the same: the gra di ent of the val ley floor de creases where streams ap proach this folded struc ture, and it increa- ses where streams leave the axis of this struc ture (Fig. 2).
The re sults re fer ring to the East ern fore land of the East - ern Alps are de scribed is Kovács (in this vol ume).
The study was sup ported by Hun gar ian Sci en tific Re - search Fund (OTKA NK83400) and was re al ized in the frames of TÁMOP 4.2.4.A/2-11-1-2012-0001 high pri or ity
“Na tional Ex cel lence Pro gram – Elab o rat ing and Op er at ing an In land Stu dent and Re searcher Per sonal Sup port Sys tem con ver gence pro gram” pro ject’s schol ar ship sup port. BS con trib uted partly as an Al ex an der von Humboldt Research Fellow.
Ref er ences
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Fig. 2. As pect map of the study area with river style in ves ti ga tion re sults and de rived lin ea ments (for lo ca tion see Fig. 1). 1 – de rived lin ea - ments, sup posed fold axes; 2 – na tional bor der be tween Aus tria and Hun gary; 3 – main streams; 4 – in creas ing stream gra di ent; 5 – de creas - ing stream gra di ent; 6 – pre sum ably struc tur ally pre formed val ley; 7 – rel a tive up lift.
