Magnetostratigraphy: the key to a global correlation of the classic Germanic Trias-case study Volpriehausen Formation (Middle Buntsandstein), Central Germany

摘要

An integrated lithostratigraphic-magnetostratigraphic study was carried out in order to provide a magnetic record for the Volpriehausen Formation of the classic Germanic Trias. In its type area of Central Germany, the similar to150-m thick Volpriehausen Formation consists of nine small-scale fining-upward cycles, ranging from about 10 to 20 m in thickness. They can readily be correlated over large parts of the Central European Basin using a combination of cyclic stratigraphy and gamma ray logging. Based on this robust high-resolution lithostratigraphic framework, a precise positioning and verification of paleomagnetic data has been realized. To this end, the classic outcrop Kleines Bodetal and the continuously cored well Bockenem A100 were collected, yielding a total of 361 paleomagnetic samples. From about 87% of them, a characteristic remanence was obtained in both the magnetite-bearing gray lithologies as well as the hematite-bearing red-brown lithologies. The between-site correlation allows the creation of a well-defined composite magnetostratigraphy of the uppermost Bernburg Formation to lowermost Detfurth Formation, encompassing a total of five magnetic polarity intervals, which can be combined unambiguously with a recently established polarity scale for the uppermost Zechstein and Lower Buntsandstein. Moreover, the resulting composite magnetostratigraphy can be correlated with corresponding records from the Continental, Boreal, and Tethyan realms. Thus, the Buntsandstein magnetostratigraphy is important in that it provides valuable anchors to link the Germanic Trias high-resolution lithostratigraphy to the biostratigraphically calibrated Triassic substages. (C) 2004 Elsevier B.V. All rights reserved.