TY - JOUR
T1 - Comparative palynofacies, magnetic susceptibility and cyclicity of the Middle Devonian Müllertchen Section (Eifel area, Germany)
AU - Brocke, Rainer
AU - Brett, Carlton E.
AU - Ellwood, Brooks B.
AU - Hartkopf-Fröder, Christoph
AU - Riegel, Walter
AU - Schindler, Eberhard
AU - Tomkin, Jonathan H.
N1 - Sincere thanks are expressed to the technical assistants of the Senckenberg Research Institute Frankfurt, namely Michael Ricker who prepared sedimentological samples and Jutta Oelkers-Schaefer who processed the palynological samples. We are very grateful to Maria Mönnig (Üxheim-Ahütte) and Sue Ellwood for support in the field. This study is a part of ongoing field research on the Devonian of Germany funded by a Humboldt Foundation Research Prize awarded to C.E. Brett. Thanks are also extended to the Robey Clark endowment to LSU for partial support of B.B. Ellwood. J.E.A. Marshall and an anonymous reviewer are acknowledged for their constructive comments, which helped to improve the paper. We also thank the editors for careful handling.
PY - 2017/9/1
Y1 - 2017/9/1
N2 - The recognition of subtle small-scale cycles in “monotonous” calcareous mudstone intervals requires a multi-disciplinary approach. In the classical Eifel area of Germany, a section of lower Givetian calcareous rocks is exposed in the well-known Müllertchen Quarry near Üxheim-Ahütte. Lying on top of limestones of the Lahr Member of the Ahbach Formation, a succession of calcareous mudstones (marlstones) is developed. This succession contains diverse brachiopods, corals and bryozoans, which are mostly small, especially in the lower part. In the present study, we focus on the combination of lithology, palynological content and magnetic susceptibility in order to evaluate whether a cyclic pattern is developed and can be mirrored by these methods. The lithological succession shows a rather homogenous marly sequence interrupted by a few more rigid calcareous beds; two of them are known as the Lower and Upper Wurmweide beds, which yield traces of Chondrites on the upper surface. For palynological analyses, 19 samples were obtained from a 4-m interval in the marly succession. Eighty samples were collected at regular spacing through the same interval, for magnetic susceptibility analysis. Palynofacies analysis has been carried out, and the assemblage of leiosphaerids, acritarchs, scolecodonts and miospores reflects the lithology. In particular, the distribution pattern, abundance and ratios of leiosphaerids and miospores can be applied for palaeoenvironmental interpretation. Patterns of change in proportion of these two groups match that of the magnetic susceptibility. These combined data indicate small-scale cyclicity, even within a relatively monotonous, thin stratigraphic interval.
AB - The recognition of subtle small-scale cycles in “monotonous” calcareous mudstone intervals requires a multi-disciplinary approach. In the classical Eifel area of Germany, a section of lower Givetian calcareous rocks is exposed in the well-known Müllertchen Quarry near Üxheim-Ahütte. Lying on top of limestones of the Lahr Member of the Ahbach Formation, a succession of calcareous mudstones (marlstones) is developed. This succession contains diverse brachiopods, corals and bryozoans, which are mostly small, especially in the lower part. In the present study, we focus on the combination of lithology, palynological content and magnetic susceptibility in order to evaluate whether a cyclic pattern is developed and can be mirrored by these methods. The lithological succession shows a rather homogenous marly sequence interrupted by a few more rigid calcareous beds; two of them are known as the Lower and Upper Wurmweide beds, which yield traces of Chondrites on the upper surface. For palynological analyses, 19 samples were obtained from a 4-m interval in the marly succession. Eighty samples were collected at regular spacing through the same interval, for magnetic susceptibility analysis. Palynofacies analysis has been carried out, and the assemblage of leiosphaerids, acritarchs, scolecodonts and miospores reflects the lithology. In particular, the distribution pattern, abundance and ratios of leiosphaerids and miospores can be applied for palaeoenvironmental interpretation. Patterns of change in proportion of these two groups match that of the magnetic susceptibility. These combined data indicate small-scale cyclicity, even within a relatively monotonous, thin stratigraphic interval.
KW - Cyclicity
KW - Givetian
KW - Magnetic susceptibility
KW - Palynology
KW - Rheinisches Schiefergebirge
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U2 - 10.1007/s12549-017-0289-9
DO - 10.1007/s12549-017-0289-9
M3 - Article
AN - SCOPUS:85021757902
SN - 1867-1594
VL - 97
SP - 449
EP - 467
JO - Palaeobiodiversity and Palaeoenvironments
JF - Palaeobiodiversity and Palaeoenvironments
IS - 3
ER -