Microbial fabric formation in spring mounds ("microbialites") of alkaline salt lakes in the Badain Jaran Sand Sea, PR China
Zeitschrift: Palaios, 199813, 6: 581 - 592
Arp, Gernot; Hofmann, Jürgen; Reitner, Joachim, 1998: Microbial fabric formation in spring mounds ("microbialites") of alkaline salt lakes in the Badain Jaran Sand Sea, PR China. In: Arp, Gernot; Hofmann, Jürgen; Reitner, Joachim (1998): Microbial fabric formation in spring mounds ("microbialites") of alkaline salt lakes in the Badain Jaran Sand Sea, PR China - Palaios, Vol. 13, 6, p. 581-592, DOI: 10.23689/fidgeo-2568.
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The large sandy desert of Badnin Jaran Shamo, Inner
Mongolia, has several salt lakes located among megadunes
with crests as high as 400 m. Most of the lakes are hypo- to
hypersaline and alkaline, with pH values between 8.5 and
10. Because of their reef-like aragonitie pinnacles rising
from the lake floor, Lake Nuoertu and Lake Huhejaran haue
been investigated in detail. The porous limes tones of the
tufa pinnacles ("spring mounds'') result {rom a hydrochemieally
forced, exopolymer-mediated calcification of cyanobacteria-
dominated mierobial mats at sublacustrine
springs. The development oftheir enigmatie fabries is documented
for the first time. Siekle-cell-like and bubbleshaped
fabries reflect successive mineralization during degradation,
shrinkage of the organie mucus, and gas formation
by bacteria. Fossil analogues are known from the Pleistocene
and Miocene (Ries-crater lake), but older non-marine,
Phanerozoie examples are expected. 1b the extent that
these textures are associated exclusively with alkaline environments,
they can be used to test the hypothesis of an alkali
ne ocean early in Earth history.
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