Palynofazies, Bio- und Lithostratigrafie im Grenzbereich Trias/Jura in der Bohrung Mariental 1 (Lappwaldmulde, Ostniedersachsen)

In well Mammal I. drilled in the Lappwald Syncline, the complete section from the higher part of the autochthonous Hettangian to the top of the Contoria Beds was cored It was the first time ever in this region, that the Triassic/Jurassic boundary had been cored The stratigraphic sequence was investigated in detail using logs and sedimentological as well as palynological and micropalaeontologcial methods It was subsequently linked to the regional lithostratigraphy of the Upper Keuper and Lower Liassic strata of the Lappwald Syncline All 98 palynological samples contain numerous palynomorphs and allow, apart from a biostratigraphical classification, a detailed facies analysis Generally, within the sequence there is a remarkably small amount of marine microplankton and a noticeably fluctuating content of pyrite Both, the facies as well as the kerogen analysis confirm a paralic, deltaic to lagoonal sedimentary depositional environment with a large supply of land-derived organic material The alternation between continental and marine environments is also reflected in the microfauna and megaspores. To a large extent the state of preservation of the marine microfauna is mostly inadequate (stony cast preservation, partly pyritized). Despite the good preservation of the megaspores, their biostratigraphical validity is unsatisfactory A temporarily exposed outcrop section near Langelsheim (Harz), comprising the same Lower Jurassic stratigraphical sequence, was investigated at the same time as the Mammal 1 core In contrast to the cored section ills a strongly condensed sequence which is only marginally suitable for comparison.