Heavy Minerals as Indicators of the Source and Stratigraphic Position of the Loess-Like Deposits in the Orava Basin (Polish Western Carpathians)

Dorota Chmielowska,Dorota Salata

doi:10.3390/min10050445

Abstract

This study is focused on the loess-like deposits accumulated on glaciofluvial fans of the Czarny Dunajec River in the Orava Basin (Southern Poland). The deposition of these sediments took place during three cold intervals of the Pleistocene: Würm, Riss, and Günz/Mindel. So far, the provenance and age of the deposits has not been precisely defined, even though the development of each fan is believed to be related to the successive glacial periods in the Tatra Mountains. Heavy minerals were studied to determine the source of the deposits. Heavy mineral analyses revealed that zircon, tourmaline, rutile, garnet, amphibole, epidote, and apatite are the typical constituents of the heavy mineral fraction. Abundances of heavy minerals differ in each of the Pleistocene fans of the Czarny Dunajec River, especially the amphibole content. However, the chemical composition of garnet, amphibole, and tourmaline is rather uniform. This research showed that mainly medium-grade metamorphic rocks with a subordinate share of high-grade metamorphics, and granitic rocks are the dominant source rocks of the deposits studied. Such rocks are exposed in the Western Tatra Mountains, which most probably supplied the Orava Basin with clastic material. Change in abundances of heavy minerals in the succession may reflect the progressive erosion of the source area. Grain-size distribution and textural features of the sampled sediments suggest fluvial and aeolian modes of transportation. Additionally, this study indicated that heavy minerals may be used to correlate the loess covers in the Orava Basin.

Highlights

Heavy minerals are commonly used to track the sources of deposits and transport directions, reconstruct depositional environments, recognize the paleogeography of the source area or types of post-sedimentary processes affecting the sediments [1].Loess-deposits cover one-tenth of the earth’s surface [2,3,4], recording important information on the paleoatmospheric patterns and climate change (e.g., [5,6,7,8,9,10,11,12,13])
Material for the heavy mineral analyses was collected from the loess-like deposits in three study sites (Chochołów, Chyżne, and Čimhova) representing three glaciofluvial fans of the Czarny Dunajec in the Orava Basin, each corresponding to a different age (Figure 1)
This study shows an additional advantage of the heavy mineral analyses in the study area

Summary

Introduction

Heavy minerals are commonly used to track the sources of deposits and transport directions, reconstruct depositional environments, recognize the paleogeography of the source area or types of post-sedimentary processes affecting the sediments [1].Loess-deposits cover one-tenth of the earth’s surface [2,3,4], recording important information on the paleoatmospheric patterns and climate change (e.g., [5,6,7,8,9,10,11,12,13]). Heavy minerals are commonly used to track the sources of deposits and transport directions, reconstruct depositional environments, recognize the paleogeography of the source area or types of post-sedimentary processes affecting the sediments [1]. One of the fundamental problems posed by loess deposits is the identification of their potential source areas. It is believed that this is the first step toward understanding how the production of the dust fraction took place, its incorporation in the transport mode, transport and depositional conditions [2]. Dust from different source areas may be homogenized in the atmosphere, causing serious problems with the identification of individual source areas [2,14,15,16]. Determining the composition of heavy mineral assemblages in loess is important for places where, theoretically, material supply seems to be limited by orographic barriers

Methods

Results

Discussion

Conclusion