biostratigraphy and paleoecology of cretaceous/tertiary boundary in ...

Chapter Two
Lithostratigraphy
medium to massive well bedded ridge forming recrystalized pale grey
limestone and sandstone to silty limestone occasionally dolomitized rich in
rudist and other macro and microfossils intercalated by with beds of shale and
calcareous shale at the lower and upper part of this interval. The Aqra
Limestone interval overlained by 67m of Tanjero Formation with alternation of
bluish white marl, marly siltstone, thin bedded recrystalized fossiliferous
limestone and weathered pale grey friable sandstone layer with some pebbly
sandstone, clay ball and pillow structure.
The third unit of this section is transitional zone 35m of clastic increasing
upward consists of reddish weathered friable sandstone pebbly sandstone
rich in reworked Loftusia, Omphalocyclus and Orbitoides fig(2.8a) at the base
and followed by alternation grey shale, marl, friable detrital sandy limestone
with purple to reddish claystone, and two conglomerate beds at the upper part
of this interval, the conglomerate genetically comprises igneous, metamorphic
and sedimentary origin of the pebbles and they extended laterally for limited
short distances. This interval is characterized by shell debris of macrofossils
such as solitary corals cyclolites, echinoids, dwarfed gastropods, and
pelecypodes.The transition interval overlained by typical molasses of Red Bed
Series in this section marked by 3m of friable brownish weathered
conglomerate of metamorphic and sedimentary pebbles and complete reddish
color (fig 2.8b) with reworked dwarfed fossils of corals, brachiopod, echinoid,
gastropod and pelecypods, followed by red beds of claystone, sandstone,
pebbly sandstone. It is important to mention that in addition to Kato and
Qishlagh sections, other three preliminary outcrops were taken into
consideration for sampling on Tanjero/ Red Bed contact like (Zardabee,
Tagaran and Shakha Sur) sections in order to get high foraminiferal
survivorship recovery, but it proved useless result from the foraminiferal
recovery point of view.
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