Original paper

Origin of Eocene-covered karst bauxites of the Transdanubian Central Range (Hungary): evidence for early Eocene volcanism

Dunkl, István

European Journal of Mineralogy Volume 4 Number 3 (1992), p. 581 - 596

69 references

published: Jun 11, 1992
manuscript accepted: Dec 11, 1991
manuscript received: Aug 8, 1991

DOI: 10.1127/ejm/4/3/0581

BibTeX file

ArtNo. ESP147050403002, Price: 29.00 €

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Abstract Fission track (FT) ages measured in detrital zircon crystals from Eocene-covered bauxites of the Transdanubian Central Range (TCR) appear to reflect the cooling age of the source rock(s). Thus, by means of FT-dating of zircons new information could be obtained to explain the problem of source rocks debated so far. Since the majority of the detrital zircon crystals proved to be euhedral, their typologic analysis permitted conclusions regarding the petrographic character of the source rocks as well. (1) In the light of the age results it is clear that the pyroclastics of a Pre-Middle Eocene volcanism contributed to the bauxite material which was deposited on the exposed karstified carbonate terrain. Andesitic tuffite layers intercalated in the upper part of the overlying Eocene sequence are traces of younger explosions of the same Paleogene volcanic event. Zircon grains found in the bauxite are morphometricaHy identical to those found in the younger Eocene pyroclastics of andesitic character. (2) A euhedral zircon population of 210 to 260 million years was also identified in some of the bauxite deposits studied. These crystals derive most probably from Middle Triassic trachyandesite tuffs of the Central Range, though anatectic granitic sources cannot be excluded. (3) Those zircon grains which are the oldest and fairly well rounded are thought to derive from the parametamorphic of Hercynian age of the surrounding areas. The bauxites of the TCR, though obviously of polygenetic origin, clearly received considerable amounts of pyroclasic contribution related to a Lower Eocene to Lower Lutetian volcanic event and this probably played an important role in the formation of the deposits


bauxitezircon typologyfission track datingEocene volcanismHungary