Dinocyst zonation and lithostratigraphy of the Miocene succession in the Schillsdorf borehole, Neumünster, Germany

This report presents the results of a biostratigraphic analysis of the Miocene succession in the borehole Schillsdorf based on fossil dinoflagellate cysts (dinocysts). The borehole is located southeast of the village Schillsdorf, east of Neumünster, Germany (Fig. 1) and was drilled in 2015 using the “straight flush”-drilling method.

In previous studies from 2010 and 2015, respectively, it was proven that the dinocyst zonation of Dybkjær & Piasecki (2010), defined for the Danish Miocene succession, could be applied to the Miocene succession in the Schleswig-Holstein area. A detailed and well-documented correlation between the Miocene succession in the German Westerlangstedt borehole and the succession in the southern part of Jylland, Denmark, was presented in Dybkjær & Rasmussen (2010). In Dybkjær (2015) a borehole at Schulensee were likewise dated and correlated with the Danish Miocene succession and with the Westerlangstedt borehole.

The purpose with the present study is to date the Miocene part of the drilled succession in the Schillsdorf borehole, to refer the succession to the dinocyst zonation of Dybkjær & Piasecki (2010), and to subdivide the succession into lithostratigraphic units. Unfortunately, only the lower part of the supposed Miocene succession (from 114 m and downwards) was sampled, as the interval from 78 m and down to approxiamtely 110 m previously was interpreted as being part of the Quaternary.

The sampled Miocene part of the studied succession (187 m - 114 m) is subdivided into the dinocyst zonation defined by Dybkjær & Piasecki (2010). Based on the dinocyst stratigraphy combined with the lithology and the gamma ray log pattern, the succession was further subdivided into the lithostratigraphic units of Rasmussen et al. (2010) and correlated with the succession in the Schulensee borehole, the Westerlangstedt borehole and with the Danish Miocene succession. The Miocene succession unconformably overlies Rupelian to lower Chattian clay, referred to dinocyst zone D14 of Köthe (1990; 2003). Minor reworking of Jurassic and especially Palaeogene palynomorphs was found throughout the studied succession. In addition, a few caved dinocysts were recorded.

The following dinocyst zones were found:
204 m - 187 m: D14
187 m - 181 m: The Homotryblium spp. Zone
181 m - 175 m: The Caligodinium amiculum Zone
175 m - 172 m: The Thalassiphora pelagica Zone
172 m - 114 m: The Sumatradinium hamulatum Zone

The Miocene succession thus comprises the interval from the lower Aquitanian to the lower Burdigalian, Lower Miocene.

Based on a combination of the dinocyst stratigraphy, the lithology of the samples and the geophysical log-pattern, the studied succession was subdivided into the Miocene lithostratigraphic units defined in the Danish area (Rasmussen et al., 2010) (the corresponding German lithostratigraphic units are mentioned in paranthese);
1) 187 m - 181 m: The Vejle Fjord Formation (=”Unterer Glimmerton”)
2) 181 m - 150 m: The Klintinghoved Formation (= “Unterer Glimmerton”)
3) 150 m - 145 m: The Bastrup Formation (= “Unterer Braunkohlensande”)
4) 145 m - 134 m: The Klintinghoved Formation (= “Unterer Glimmerton”)
5) 134 m - 120 m: The Bastrup Formation (= “Unterer Braunkohlensande”)
6) 120 m - 105 m: The Klintinghoved Formation (= “Unterer Glimmerton”)
7) 105 m - 100 m: The Stauning Member of the Odderup Formation (= “Obere Braun-kohlensande”)
8) 100 m - 78 m: The Odderup Formation (= “Obere Braunkohlensande”)

The Miocene succession is unconformably overlain by Quaternary deposits.