Name 1
MID-TRIASSIC EROSION SURFACE WITH DISCORDANT POSITION OF LADINIAN DOLIMITE CONGLOMERATE ON CARBON SLATE
Name 2
/
ID number
002.3.Idrija
Manager / Administrator
Idrija Mercury Heritage Management Centre, Bazoviška 2, SI-5280 Idrija
Ownership
Public
Owner
Republic of Slovenia
Local / Original ID Number
Geological profile 1, part 4644 Idrija ore deposit
Type of Object
Ore deposit

Description

Short description
On the Anthony's Main Road level, approximately 120m from the entrance, a Mid-Triassic erosion gap is visible, the contact between the carbon slates and Ladinian conglomerate. The layers have an inverse position, which applies for the entire upper structure of the Idrija ore deposit. Due to the inverse position, dark grey to black carbon slate lies on top and discordantly above it (below) there is approx. 15cm of Ladinian dolomite conglomerate. Dolomite pebbles are beautifully visible on the profile. Conglomerate is overlapped (due to the inverse position below) by smaller tuffites.
Measures
The tunnel intersection is approx. 2 × 2 m.
Materials
Slate, dolomite conglomerate, tuffites
Dating
Approximately 238 million years ago, in the Mid-Triassic tectonic stage, which took place in middle and upper Anisian and Ladinian.
Author / Producer
/
Picture attachments
Original use
Two strong tectonic phases contributed to the creation of the ore deposit. The contact between carbon slate and conglomerate is an erosional gap, which is the result of the first and second erosion periods. In the first phase, at least 750m of Anisian, Scythian, Permian and partially carbon rocks were removed, and at least 50m of rocks in the second phase. From erosionally removed rocks different breccias and conglomerates were created. After the conglomerate was deposited, it was immediately covered by volcanic ash. The rocks follow one another by age, therefore the contact between the tuffite and the dolomite conglomerate is normal.
Present use
The Idrija ore deposit and Anthony's Main Road gained the status of a geological natural value of national importance in 2004. In the Anthony's Main Road area, eight geological profiles of the utmost importance are registered, which represent an important part of the European naturalistic heritage. In these geological profiles, the development elements, which were involved in the creation and formation of mercury ore deposit, are preserved. At the same time, also the numerous tectonic events, which transformed the original Mid-Triassic mine structure into the current condition. Geological profiles are on display for visitors of Anthony's Main Road, geology students and professional groups. In the described profile, the erosion contact between carbon slate and Ladinian conglomerate is open, which is the result of both erosional Mid-Triassic periods. This is a rarely seen geological phenomenon.
Original location
Idrija ore deposit, Anthony’s Main Road.
Present location
Anthony’s Main Road (top pit building, south mine unit on the level of Anthony's Main Road, 120 m from the entrance), Kosovelova 3, 5280 Idrija

STATE OF CONSERVATION

History of conservation:
/
Present state
good
Necessary activities:
Performing regular maintenance services by the programme, including status control and preservation, security and presentation of the heritage.

DOCUMENTATION

Addresses / collections / links etc. where further in-depth information is accessible:
- Official Gazette of the Republic of Slovenia no. 111/2004 of 14/10/2004 4623. Rules on the designation and protection of natural values, p. 13173–13175; https://www.uradni-list.si/glasilo-uradni-list-rs/vsebina/51517. See: Annex 1: Seznam naravnih vrednot in njihova razvrstitev na vrednote državnega in lokalnega pomena;
- Čar, Jože. Opis najpomembnejših geoloških profilov v odprtem delu idrijske jame. Tipkopis, 9 strani, 4 priloge, 35 fotografij s komentarjem in 6 jamskih kart. CUDHg, Idrija, 2017.
Submitted
Mestni muzej Idrija
Submitted by
Miha Kosmač
Date Submitted
27. 2. 2018
Date Edited
Never