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Jiří Otava
TRACING THE ORIGIN OF CAVE SANDS:
STATE OF THE ART IN THE MORAVIAN KARST
17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
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Variscan Europe and Moravian Karst, Czech Republic

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
…it is very easy to know the provenance of cave sands near the ponor…

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
…but it is sometimes very difficult to recognize the sources of cave sediments
when you are deep inside the limestone massif:

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
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Assemblages coming from the western sources
 (Neoproterozoic granitoids and Devonian clastics):
Translucent heavy mineral assemblage derived directly from Devonian clastics and granitoids of the
Brno Massif, locality 1 on fig. 1, Suchdolský ponor, Dóm Juniorů.

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY


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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY


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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
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Assemblages coming from the northern sources:
Lower Carboniferous, Mississippian
(greywackes of the Protivanov F.):
Translucent heavy mineral assemblage of the northern Culmian greywacke, locality 2 on fig. 1,
Helišova skála.

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY


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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
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Assemblages coming from the eastern sources
Lower Carboniferous, Mississippian
 (greywackes of the Rozstání and Myslejovice Fms.):
Translucent heavy mineral assemblage of the Culmian
greywacke at NE, locality 3 on fig. 1, Krasovský potok Valley.
Translucent heavy mineral assemblage of the Culmian
greywacke easterly from the Moravian Karst, locality 4 on fig. 1, Habrůvka Village.
Translucent heavy mineral assemblage of the Culmian
greywacke SE from the Moravian Karst, locality 5 on fig. 1, Hádek near Ochoz.

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY


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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
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Assemblages  coming  from  the  paleokarst  fill,
Cretaceous, Cenomanian
 (sands of the Rudice Formation):
Translucent heavy mineral assemblage
of the Cretaceous sands, locality 6 on fig. 1, Rudice-Seč.

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
Cretaceous (Cenomanian) kaolinic quartz sands in a palokarst depression, locality 6 on fig. 1,
Rudice-Seč

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
Assemblages coming from the lower Miocene sands:
Translucent heavy mineral assemblage of the terrestric Miocene, locality 7 on fig. 1, Ostrov,
borehole OM3. ZTR means ultrastable minerals zircon + tourmaline + rutile.

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
Distiguishing of source of cave sands in the northern part of the Moravian Karst:
terrestric Miocene source;

eastern Culmian source;
western and northern sources.

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
Cave sands of the Macocha Abyss and its closest vicinity are divided in two groups with different
provenance:
The first one (    ) comes from Cretaceous paleokarst fill (staurolite, kyanite, tourmaline,
rutile), while the other one (    )
comes mainly from the western vicinity of the Moravian karst ((epidote, amphibole) with various
admixture
of the eastern source (garnets).

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
Kyanite – one of the most characteristic heavy mineral of the Cretaceous paleokarst fill. Photo in
crossed polars.

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
Conclusions
•The metod of translucent heavy mineral analyses has been used to trace the provenance af cave
sands in the Moravian Karst.
•Several examples of distiguishing the source of sands in enigmatic positions are presented.
•The first one shows differences between cave sands coming from W and N, i.e. from granitoids and
old Culmian rocks, from E (younger Culmian rocks) and from terrestric miocene
•The other example was taken from cave sands in the close vicinity of the Macocha Abyss.
•The result shows mixing of prevailing western source with minor share of easten source and another
clearly different source – the products of Cretaceous paleokarst fill.
•One of main goals of the analyses is to establish the paleohydrography of Moravian Karst (or any
other karst)
•and off course to show possibilities of new discoveries

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17TH INTERNATIONAL CONGRESS OF SPELEOLOGY, SYDNEY, AUSTRALIA 2017 JULY
Thank you for your kind attention