Weathering by dolomite dissolution responsible for the formation of an important palaeontological locality in the Prague Synform

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985891%3A_____%2F18%3A00496386" target="_blank" >RIV/67985891:_____/18:00496386 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.irsm.cas.cz/materialy/acta_content/2018_doi/Rowberry_AGG_2018_0022.pdf" target="_blank" >https://www.irsm.cas.cz/materialy/acta_content/2018_doi/Rowberry_AGG_2018_0022.pdf</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.13168/AGG.2018.0022" target="_blank" >10.13168/AGG.2018.0022</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Weathering by dolomite dissolution responsible for the formation of an important palaeontological locality in the Prague Synform

Popis výsledku v původním jazyce

Karst landforms can result from a single stage process in which chemical dissolution and mechanical erosion proceed simultaneously or from a two stage process in which chemical dissolution recedes mechanical erosion. During the second of these processes, chemical dissolution leads to the creation of karst features hosting a residual weathering product, here referred to as alterite. An example of one such feature is the enclosed mass of altered rock at Červený Quarry near Klukovice which represents one of the richest localities for exceptionally preserved echinoderm ossicles in the Prague Synform. In this study the processes responsible for the formation of this feature have been investigated. Nineteen samples were obtained from the bioclastic Slivenec Limestone and from these it has been possible to calculate the carbonate volume content, which defines the weathering intensity, and the carbonate rock weathering index, which defines the weathering state. The results demonstrate that carbonate dissolution has not been accompanied by gravitational compaction or the incorporation of mineral inputs. Thin sections analysed under polarised light and under cathodoluminescence emphasise heterogeneous dolomitisation of the limestone. As the weathering grade intensifies, empty rhomboidal pores become increasingly common until, ultimately, the rhomboidal forms are lost due to corrosion and enlargement. In contrast it is rare to find evidence of calcite dissolution and, therefore, the altered mass still hosts almost all of its post dolomitisation micrite, sparite, and bioclasts. Negligible calcite dissolution helps to explain the exceptional nature of the fossil preservation at the site while the dolomite dissolution accounts for the ease with which it is possible to extract the fossils. Further research should focus on better understanding the role of dolomite dissolution in the formation of other important palaeontological localities in the Prague Synform.

Název v anglickém jazyce

Weathering by dolomite dissolution responsible for the formation of an important palaeontological locality in the Prague Synform

Popis výsledku anglicky

Karst landforms can result from a single stage process in which chemical dissolution and mechanical erosion proceed simultaneously or from a two stage process in which chemical dissolution recedes mechanical erosion. During the second of these processes, chemical dissolution leads to the creation of karst features hosting a residual weathering product, here referred to as alterite. An example of one such feature is the enclosed mass of altered rock at Červený Quarry near Klukovice which represents one of the richest localities for exceptionally preserved echinoderm ossicles in the Prague Synform. In this study the processes responsible for the formation of this feature have been investigated. Nineteen samples were obtained from the bioclastic Slivenec Limestone and from these it has been possible to calculate the carbonate volume content, which defines the weathering intensity, and the carbonate rock weathering index, which defines the weathering state. The results demonstrate that carbonate dissolution has not been accompanied by gravitational compaction or the incorporation of mineral inputs. Thin sections analysed under polarised light and under cathodoluminescence emphasise heterogeneous dolomitisation of the limestone. As the weathering grade intensifies, empty rhomboidal pores become increasingly common until, ultimately, the rhomboidal forms are lost due to corrosion and enlargement. In contrast it is rare to find evidence of calcite dissolution and, therefore, the altered mass still hosts almost all of its post dolomitisation micrite, sparite, and bioclasts. Negligible calcite dissolution helps to explain the exceptional nature of the fossil preservation at the site while the dolomite dissolution accounts for the ease with which it is possible to extract the fossils. Further research should focus on better understanding the role of dolomite dissolution in the formation of other important palaeontological localities in the Prague Synform.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10505 - Geology

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Acta geodynamica et geomaterialia

ISSN

1214-9705

e-ISSN

—

Svazek periodika

15

Číslo periodika v rámci svazku

3

Stát vydavatele periodika

CZ - Česká republika

Počet stran výsledku

13

Strana od-do

297-309

Kód UT WoS článku

000446886800007

EID výsledku v databázi Scopus

2-s2.0-85055333753