Lake Pavin History, geology, biogeochemistry, and sedimentology of a deep meromictic maar lake

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22.5 Sedimentary Environments
in the Deep Central Basins of Lakes
Chauvet and Pavin

22.5.1 Lake Chauvet Basin

The deep central basin of Lake Chauvet is clearly imaged by
12 kHz sub-bottom acoustic profi les (Fig. 22.6 ). It is fi lled by
up to 4.6 m thick well-stratifi ed deposits were few continu-
ous refl ections are terminate by onlap against the edges of
the basin and the moraine ridges. Locally, moraine ridges

can also be partly draped by a thin layer of sediment devel-

oping a transparent acoustic facies.

Down slopes from the lake tributary, the MWD rework-

ing slope sediments forms a lens-shaped body at the edge of

the basin where it is characterized by a transparent to chaotic

facies. This body is laterally thinning toward the central

basin into a distinct high amplitude refl ection that has been

sampled in short core CHA13-7B (Fig. 22.6 ). Such a succes-

sion of acoustic facies is typical of a mass wasting phenom-

ena evolving downslope from a mass movement into a

Lake Pavin crater geomorphology

outlet

subaquatic

plateau

littoral

lake shore

isoline (5 m), tracks and paths

cliff

thalweg

Topographic features

Subaquatic features

isobath (2 m)

slide scar

outcroping lavas

canyon

Subaquatic

outlet?

• 26 m

crater ring

• 60 m

central

basin

Limnologic features

oxic waters

(mixolimnion)

anoxic waters

(monimolimnion)

-12 m

-26 m

Fig. 22.10 Lake Pavin crater
geomorphology from the
crater ring to the deep central
basin illustrating key
topographic, subaquatic and
limnologic features of this
young and deep meromictic
crater lake

22 Pavin Sedimentary Environments