Monday, August 30, 2010

Field trip to the chalk-quarry Laegerdorf

In July our small group of hobby-micropaleontologists heads to the chalk-quarry Laegerdorf near Hamburg: doors are open, it its collectors Sunday. While our macropaleontological colleagues are already busy with their heavy equipment and first findings of belemnites are reported we discuss the stratigrafical setting:

We soon skip our plan to match stratigrafical maps in the literature with sampling in the quarry. We do a chronological sampling and hope, that the micropaleontological content will tell us more.

After 7 hours of continous sampling we have 15 bags of 500g. Mircofossils are not observable, with a magnifying glas: 0,00.
What have you got ? is the question of our colleagues with the buckets full of belemnits, starfish, sponges ...
Yeah , oh my god - us ? - we don't know ...

Our field trip starts back home. After cleaning, washing, sieving of 1/3 of the first bag a residue with fraction > 63µm is left:

In three such spoons we find hundreds of foraminifera and other microfossil specimens. Cleaning needs to be improved though.

Some prominent index foraminifera for the Lower Upper Campanian/ Upper lower Campanian found are these:

Neoflabellina buticula

Stensioeina pommerana

Bolivinoides decoratus (var. decoratus ?)

Learn more about our findings at
Laegerdorf Sample 22

Tuesday, August 10, 2010

Globorotalia truncatulinoides

Globorotalia truncatulinoides (d'Orbigny, 1839) is a planktic foraminifera.

It tolerates a broad range of sea surface temperatures and salinities and occurs in subtropical and transitional water masses. It is a deep-dwelling species which ascends to shallower depths during its reproduction period in winter. In the fossil record it is since the Pleistocene and may be used for studies on climate change of the last 2 mya.

The relative abundance of dextral coiling is higher at lower latitudes.

The specimens shown here are from a sample from the Hebridian Slope off Scotland in the North Atlantic. Northwest of the British Isles, this steep continental slope to depths greater than 2000 m separates the distinct continental shelf of Europe from the deeper Atlantic Ocean. The sample is in the repository of the Scottish Association for Marine Sciences, Oban.

see more foraminifera found at the Hebridian Slope

Umbilical view of a
dextral coiling specimen

Spiral View

more images of Globorotalia truncatulinoides at
Laboratório de Microfósseis Calcários,
Rio Grande do Sul, Brasil