Geneza polew naciekowych z Jaskini Psiej i Naciekowej w Tatrach Zachodnich

Piotr Dziadzio, Roman Różniak, Joachim Szulc

Abstrakt


ORIGIN OF THE PLEISTOCEN CALCITE FLOWSTONES OF TWO CAVE (JASKINIA PSIA AND JASKINIA NACIEKOWA) IN THE WEST TATRA MTS

Summary

The Pleistocene calcite flowstones of two caves systems from the Tatra Mts. (Fig. 1) have been studied in terms of their growth, mechanism controlled by dynamic sedimentary processes. Microfacies analysis of the flowstones supported by chosen geochemical studies enabled a discerning of several types of the flows tone covers. They may by generally divided into rhythmically laminated and nonlaminated flowstone types. The first type comprises perfectly seasonally laminated ("varved") sets composed of coupled calcite-allophane laminae (domal mf. Fig. 11, 12 and even laminated mf. Fig. 13). The calcite lamina represents a dry season increment while the dark, clayey lamina might be attributed to wet seasons involving more intense percolation of the soil-derived clay material. The seasonal couples are grouped in bands reflecting likely longer-term climatic fluctuations. Generally the rhythmically laminated flowstones are attributed to relatively dry and warm intervals of the interglacial. The other microfacies types of flows tones are lacking rhytmic lamination and display more or less massive internal structure. This type of flow stone comprises moonmilk microfacies (mf.), (Fig. 3, 4, 5), columnar mf. (Fig. 7, 8, 9), blocky mf. (Fig. 10) and botryoidal mf. (Fig. 6). Their habit and crystal forms depend on water availability and clastic input.
The moonmilk calcite is microbiologically precipitated from solution fed by capillary and/or aerosols water. The blocky mf. is exclusively limited to basinal layers commencing every flowstone cover, and reflecting start of glacier melting. The botryoidal mf. is closely related to depositional breaks and accompany corrosion surfaces and residual clastic drapes. In contrast to the above mentioned flowstone microfacies the columnar mf. developed under stable hydrological regime and precipitated from relatively thick and pure water layer.
This type of microfacies dominates most of the flowstones and might be related to warm and humid phases of interglacial. In order to astimate age and stable isotope contents of the studied speleothems some preliminary measurements of U-Th ratio and δX13, δO18 have been made (Tab.I,II). Following the dynamic controls of the flowstone formation a qualitative rank of flowstone mf. for stable isotopes and radiometric purposes has been elaborated (Tab. III).