Results of recent Terrace Research in the Middle Rhine Valley Fig. 1.: Downstream Correlation Diagram of River-Terraces in the Lower Nahe & Upper Middle Rhine Valley. Fig. 2 & Tab. 1: Collected Sequence of the Rhine and Nahe Terraces at Bingen-Trechtingshausen Downstream Correlation Diagram of River Terraces in the Lower Nahe & Upper Middle Rhine Valley correlated with Pollen Records and Marine Isotope Stages.
Collected Terrace- MIS Elevation of Assumed Difference Incision at Lower Nahe Valley Upper Middle Rhine Valley Lower Lahn Valley Age Palaeomagnetic Marine Isotope Stages (MIS) Mean Temp.°C Sequence Base NW-European Age labels Terr. Base Mean in Age Collected 18 Nahe / Rhein LowerGÖRG Nahe(1984) Valley Upper PMiddleREUSS, BURGER & SRhineIEGLER (2015) Valley Lower ALahnNDRES & SEWERING Valley(1983); (Ma) Record (Ma) (δ OOcean‰) in July (Pollen) (m a.s.l.) Stages (Ma) Nahe / Nahe/Rhine Age Nahe/Rhine Sequence 5 4 0° 10° 20° SEWERING (1993) tRh 11.2 78 Rhine (No.) (m a.s.l.) (Ma) (Ma) Nahe/Rhine GÖRG (1984) PREUSS, BURGER & SIEGLER (2015) ANDRES & SEWERING (1983); 2 tRh 11.1 81 Weichselian (mm/a) 4 tRh 10 84 SEWERING (1993) 6 Eemian tNa 12. 1 75 0,00 0,01 0,30 tRh 9. 90 Saalian tNa 11.2 1-2 78 0,01 0,01 0,30 8 tRh 8.2 94 tNa 11.1 2 81 0,02 0,04 0,08 10 tRh 8.1 101 Holsteinian tNa 10. 4 84 0,06 0,08 0,08 12 tRh 7.4 108 Elsterian tRh 7.3 114 tNa 9. 6 90 0,14 0,11 0,04
Elevation m a.s.l. m Elevation 14+ 120 Elevation m a.s.l.m Elevation 14 tRh 7.2 Cromerian tNa 8.2 8 94 0,25 0,09 0,08 16 tRh 7.1 160 ? 18 tRh 6.5 170 tNa 8.1 10 101 0,34 0,10 0,07 tRhtRh 3.1 3.1 tLatLa 3.1 3.1 tLa 3.2 tNa 7.4 12 108 0,44 0,07 0,09 tRhtRh 3.2 3.2 tLa 3.2 20 tRh 6.4 176 tRh 3.3 tLatLa 3.3 3.3 tNa 3.2 3.2 tRh 3.3 (HT 10) 22 tRh 6.3 182 tNa 7.3 14+ 114 0,51 0,03 0,20 (HT 10) tLatLa 3.4 3.4 tRhtRh 3.4 3.4 tLatLa 3.5 3.5 tRhtRh 3.5 3.5 Bavelian tNa 7.2 14 120 0,54 0,09 0,44 tRh 6.2 186 tRh 3.5 3.5 30 tNa 7.1 16 160 0,63 0,08 0,13 34 Menapian tRh 6.1 190 tNa 6.5 18 170 0,71 0,08 0,08 36 tRh 5.2 195 tNa 6.4 20 176 0,79 0,08 0,08 42 tRh 5.1 200 Waalian tNa 6.3 22 182 0,87 0,17 0,02
48 tRh 4.3 206 tNa 6.2 30 186 1,04 0,08 0,05 tNa 7.1 7.1 ? (MT ? 7)(MT 7) 52 tRh 4.2 212 tNa 6.1 34 190 1,12 0,07 0,07 tNa 7.2 7.2 (MT 6)(MT 6) Collected Sequence Eburonian Collected Sequence tNatNa 7.3 7.3 (MT 5)(MT 5) 56 tRh 4.1 217 tRh 5.2 36 195 1,19 0,13 0,04 tNa 7.4 7.4 (MT 4)(MT 4) 60 tRh 3.5 226 tRh 5.1 42 200 1,33 0,11 0,05
tRh 4.3 48 206 1,45 0,08 0,08 68 tRh 3.4 233 tRh 4.2 52 212 1,53 0,12 0,04
tRh 4.1 56 217 1,65 0,10 0,09 78 tRh 3.3 242 Tiglian tRh 3.5 60 226 1,75 0,11 0,06 82 tRh 3.2 246 tRh 3.4 68 233 1,86 0,21 0,04
Loreley Loreley Northing tRh 3.3 78 242 2,07 0,09 0,04 (UTM 32) (UTM 32) 96 tRh 3.1 255 tRh 3.2 82 246 2,16 0,27 0,03 ? Praetiglian tRhtRh 3.3 3.3 100 tRh 2. 264 tRh 3.1 96 255 2,43 0,09 0,10 3.2 (HT (HT 10) 10) tRhtRh 3.4 3.4 tRh 3.5tRh 3.5 BRENGEL (2011) BRENGEL (2011) NotNot clear clear tRh 3.2 tRh 2. 100 264 2,52 0,19 0,05 NoNo Terrace Terrace Sediment Sediment tRh 3.2 Reuverian Sources: Landesamt für Vermessung und Geobasisinformation, Koblenz; Wasser- und Schifffahrtsamt, Bingen; Bundesanstalt für Wasserb tRh 1. 274 tRh 1. G4 274 2,71 - - Sources:au, Karlsruhe.Landesamt für Vermessung und Geobasisinformation, Koblenz; Wasser- und Schifffahrtsamt, Bingen; Bundesanstalt für Wasserb au, Karlsruhe. Figure 1: The DCD of river terraces in the Lower Nahe and Upper Middle Rhine Valley contains 28 alluvial of terraces consist of at least 17 clearly distinguishable terrace levels, which correspond to the river terraces between 200 m a.s.l. and 170 m sediment bodies. They were identified at key locations with the help of more than 720 borehole drillings, many of sequences of the Nahe and Lahn valleys (GÖRG 1984, SEWERING 1993). Taking the results of a.s.l. are arranged more or less horizontally and them in clusters, which in most cases reached the rockbed of the river terraces. The field work was based on Görg (1984) into account, further 11 levels can be identified below the jHT in the Lower Nahe river terraces below 140 m a.s.l. have a normal contour level maps derived from a LIDAR terrain model. The older study at the Nahe (GÖRG 1984) was based on Valley. In Fig. 1 the gradients of the Palaeo-Rhine (see the triangles between 240-270 m a.s.l.) gradient to the north. This diagram shows that the German Basic Map, scale 1:5,000 ("Deutsche Grundkarte 1:5.000"). Our findings show that the upper group are inversely inclined to the river´s current flow of direction - namely to the south, the hypothesis of a missing gradient is obsolete, but at the same time the longitudinal gradients Fig. 3.: Comparison of the collected Chronosequence of Nahe and Rhine with the Fig. 4.: Contour Lines of Height Changes and of the Crust-Mantle Boundary, are obviously affected by tectonic processes (see green line). Chronosequence of the Maas, with Pollen Records and Marine Isotope Stages. Epicentres of Earthquakes, and Slope Inclination.
Legend Figure 2: Using the idea of VAN DEN BERG (1996),
Epicentres a collected sequence of Nahe and Rhine terraces was arranged at Rhine-kilometre 533, using their discernible trends. The “elevations of the terrace Crust-Mantle Boundary (km) bases” from this collected sequence were matched to the cold periods of the thermal
Height interpretation of the results of pollen analysis in Changes the Netherlands (ZAGWIJN 1985, 1998), which in (Equidistance turn were correlated to the diagram of the 0,2 mm / a): Zero Line Marine Isotope Stages (COHEN & GIBBARD 2011). Using this approach, we obtained a correlation Negative with climatic events of the last 2.7 million years, Positive the standard NW-European Stages and an approximate age for the river terraces. Inclination (%) Tab 1: From Fig. 2 several relevant information 0 was extracted (terrace-labels, MIS, elevation of 0 – 1 the terrace base, assumed mean age) and new 1 – 2 2 – 3 information was calculated (difference in age, 3 – 4 incision rate for the collected sequence). 4 – 5 5 – 7 Figure 3: Two linear trends are visible in the 7 – 10 diagram, one between 0.7 Ma and 2.7 Ma, the 10 – 13 other between 0.14 Ma and 0.5 Ma. The 13 – 17 gradients of the linear equations are 52.37 m/Ma 17 – 21 for the older and 66.13 m/Ma for the younger 21 – 27 27 – 33 period. These values are fluvial incision rates, but 33 – 43 they can be interpreted as tectonic uplift rates as 43 – 53 well. The difference of 14 m/Ma is interpreted as 53 – 63 a subsidence rate of the collected 0 50 km 63 – 83 > 83 chronosequence. Of further interest is the period between 1.04 Ma and 0.51 Ma, which marks an excessively changing environment, visible in the Fig. 5.: Geomorphological Map of River Incision. climatic records and in the incision rates.
Figure 4: An explanation model for the changes in slope of the longitudinal gradients of the terraces of the upper terrace group could be derived by considering the direction and the amount of recent crustal movements in this area, which have been measured by MÄLZER et al. (1983) with the help of precision levellings. Uplift processes can be observed north of the mouth of the Lahn, and subsidence processes southeast of it. The course of the River Rhine is thus located in a zone of crust which is inclining contrary to the gradient of flow, with values increasing towards the Upper Rhine Graben. From there the research area is uplifted and partly lowered, depending on geotectonic processes of the Upper Rhine Rift Valley in the south and southeast, and the graben of the Cologne Bay in the northwest. To visualize and localize the tectonic processes, the crust-mantle boundary and epicenters were integrated (FRANKE et al. 1990; USSGS 2002; LEYDECKER 2005). SRTM-Computing: M. SCHMANKE 2007 Crust-Mantle Boundary (FRANKE et al. 1990)
Fig. 6.: Terrace Model of the Middle Rhine Valley. Fig. 7.: Evaluation of the Terrace Model with two Figure 5: The tectonic setting can be visualized with a geomorphological map of river Datasets from the Lower Middle Rhine Valley. incisions. In it we see the consequences of the collision of Africa and Europe, the uplift of the Alps, the creation of the uplifted uplands to their north and the Rhine Graben. The river incision is the calculated difference between the base of the relief, i.e. the tangential plain to the thalweg of the valleys, and the SRTM-topography. The valleys in uplifted areas as the Alps, the Vosges, the Black Forest etc. are deep (> 100 m, red), in the uplands the incision of the rivers is mainly 75-50 meters (dark green). The crust-mantle boundary visualizes and localizes the tectonic processes. Figure 6: A simple model could be calculated and designed with data from the collected chronosequence of Nahe and Rhine terraces, especially with the calculated subsidence rate of 14 m/Ma. With it the terraces could be virtually uplifted again. The base of the tRh 1. is actually at 274 m a.s.l. and has been lowered by 37 m within 2.71 Ma. Therefore the thalweg back then was positioned at 311 m a.s.l. Finally, the actual height of the rockbeds of the terraces of the collected sequence were connected to the heights of the mouth of the Lahn with red lines. The graphical result is more or less the same picture as in the Downstream Correlation Diagram (DCD) (Fig. 1.). The missing gradient of some river terraces is therefore the product of the subsidence of the Middle Rhine Valley. Figure 7: The terrace model was evaluated with two datasets from the Lower Middle Rhine Valley (BIBUS 1980, HOSELMANN 1994). We could observe that the test data fits quite well into the framework of the model. Therefore we think that the ages of the terraces, based on their correlation with the data of ZAGWIJN (1985, 1998) and COHEN & GIBBARD (2011) are quite good and representative.
Source: PREUSS, J., BURGER, D. & SIEGLER, F.: Neue Ergebnisse zur Gliederung und zum Längsgefälle der Talbodenniveaus im Mittelrheintal und an der Unteren Nahe: Revision der Hypothese der Niveaukonstanz, Berücksichtigung des Modells der aktuellen Höhenänderungen, Korrelation der Terrassensequenz mit den Marinen Isotopen Stadien und den Terrassen der Maas. Mainzer naturwissenschaftliches Archiv, Band 52, S. 5-75, 19 Abb., 8 Tab., Mainz, 2015.
Prof. Dr. Johannes Preuss, Johannes Gutenberg-Universität Mainz, Geographisches Institut, Becherweg-21, D-55099 MAINZ; E-Mail: [email protected]; Tel.: (0049)-(0)6131-39-22771