Middle – Late Jurassic (Late Bathonian – Tithonian) Palynomorphs

Abstract. INTRODUCTION

Jurassic palynomorph assemblages have been recovered in numerous wells in northeast Libya. Jurassic rocks reflect changing sedimentary environments which have greatly influenced the composition of the palynological assemblages.

In the northernmost area, Jurassic sediments unconformably overlie the Palaeozoic or Triassic and show a mixed marine and continental influence. In the northeastern part of the area thicker and deeper water marine sediments are known, while shallow marine sediments overlie the platform facies immediately to the south. Pollen and miospores are fairly well preserved and are dominant in most samples. Dinoflagellate cysts are richly represented especially in the deposits of the north and northeast. Most samples contain abundant variably sorted cuticular debris and structured wood fragments. This significant influx of terrestrial debris together with the associated palynomorph assemblages indicate deposition in a shallow marine environment in close proximity to the shoreline for most of the Jurassic deposits in the northern area.

In the central and southern region, sandstone, silt stone and red shale deposited in non-marine fluvial to lacustrine or lagoonal environment, unconformably overlie the metamorphic or igneous Precambrian Basement. These sediments show a general lack of well preserved palynomorphs. Miospores, though present are generally long ranging and terrestially derived detrital kerogen dominate the assemblages.

MICROFLORAL SUCCESSION

Miospore assemblages present in most of the samples investigated are dominated by small gymnosperm pollen. Classopollis spp., Exesipollenites spp., Sphaeripollenites spp., and nonaperturate pollen assigned to Araucariacites spp. Saccate pollen assigned to Concentrisporites spp., Perinopollenites spp., Callialasporites spp., and Inaperturopollenites spp., are often common . . .