Early Cretaceous (Neocomian-Cenomanian) Palynomorphs

Abstract. INTRODUCTION

This study is primarily concerned with the Neocomian to Aptian palynomorphs recorded in selected exploration wells (See Fig. 9). In order to document a complete Early Cretaceous microfloral succession in the studied wells, a reconnaissance of Aptian to Early Cenomanian palynomorphs was also undertaken. Details of the results from this younger interval appear in a later section.

Palynomorph assemblages vary in preservation and character. To the north, sandstone, siltstone and shale deposited in shallow-marine environments, contain well-preserved assemblages of dinoflagellate cysts, pollen and spores which can be used for stage-level age determination. A majority of the samples analysed, however, contain moderate numbers of dinoflagellate cysts, but fewer miospores. The abundance of land derived detritus indicates the relatively close proximity of the shoreline. In the central and southern parts of the study area, sandstone and siltstone that are deposited in non-marine, fluvial, lacustrine or lagoonal environments show a general paucity of well-preserved palynofloras. Miospores of stratigraphic value are generally rare or absent although the majority of the samples are dominated by land derived detritus.

PALYNOMORPH SUCCESSION

The majority of the wells from northern Cyrenaica show a hiatus at the Jurassic Cretaceous boundary. Late Neocomian or Aptian sediments occur immediately above Middle or early Late Jurassic sediments. Well preserved Neocomian palynomorphs were recorded in wells A1-36, B1-36, Bla-18 and A1-45. The stratigraphical ranges of palynomorphs presented on the plate explanations are local ranges and are based on the studied intervals only. A preliminary palynological zonation of Late Jurassic (Late Kimmeridgian) to . . .