Romanian Journal of MINERAL Geological Institute of Romania Society of Economic Geology of Romania...

Click here to load reader

  • date post

    13-Mar-2020
  • Category

    Documents

  • view

    2
  • download

    0

Embed Size (px)

Transcript of Romanian Journal of MINERAL Geological Institute of Romania Society of Economic Geology of Romania...

  • Romanian Journal of

    MINERAL DEPOSITS

    continuation of

    DARI DE SEAMA ALE SEDINTELOR INSTITUTULUI DE GEOLOGIE SI GEOFIZICA

    COMPTES RENDUS DES SÉANCES DE L’INSTITUT DE GÉOLOGIE ET GÉOPHYSIQUE

    (2. Zacaminte)

    Founded 1910 by the Geological Institute of Romania

    ISSN 1220-5648 VOL. 90 No. 1-2

    Geological Institute of Romania

    Society of Economic Geology of Romania

    Bucureşti – 2017

    CONTENT

    Sergiu DRĂGUŞANU, Călin Gabriel TĂMAŞ

    New geological data on Văidoaia mining field, Roşia Montană Au-Ag epithermal deposit,

    Apuseni Mountains, Romania ................................................................................................................ 1

    Robert SZABO, Gheorghe C. POPESCU

    Preliminary data on secondary copper minerals from the Şiglău-Uricani perimeter,

    Vîlcan Mountains, Romania ................................................................................................................. 19

    Paulina HÎRTOPANU, Robert J. FAIRHURST, Gyula JAKAB, Sorin Silviu UDUBAŞA

    Monazite-(Ce) and its associations from the Ditrau alkaline intrusive massif,

    East Carpathians, Romania .................................................................................................................. 27

    Ioan PINTEA, Elena Luisa IATAN

    The magmatic-hydrothermal history of the β-quartz polymorphs from Roşia Montană

    dacite inferred by solid-, melt-, and fluid inclusion assemblages ........................................................ 41

  • DIRECTORS

    Dr. Ştefan Marincea, General Director of the Geological Institute of Romania

    Prof. Dr. Gheorghe Damian, President of the Society of Economic Geology of Romania,

    Technical Univ. Cluj-Napoca – North Center Baia Mare

    Editor in Chief: Conf. Dr. Sorin Silviu Udubaşa (University of Bucharest).

    Editorial Secretary: Dr. Monica Macovei (University of Bucharest)

    Editorial board

    Gheorghe Udubaşa, Romanian Academy; University

    of Bucharest

    Gheorghe Popescu, University of Bucharest,

    Essaid Bilal, Ecole des Mines, Saint Etienne, France

    Georgios Christofides, Aristotle University of

    Thessaloniki, Greece

    Peter Andráš, Geological Institute of the Slovak

    Academy of Science

    Radu Jude, University of Bucharest

    Gheorghe Damian, Technical Univ. Cluj-Napoca –

    North Center Baia Mare,

    Floarea Damian, Technical Univ. Cluj-Napoca –

    North Center Baia Mare

    Grigore Buia, University of Petrosani

    Marian Lupulescu, New York State Museum, USA

    János Földessy, Miskolc University, Hungary

    Ovidiu Gabriel Iancu, "Alexandru Ioan Cuza"

    University, Iaşi

    Anne-Sylvie Andre-Mayer, Université de Lorraine,

    Nancy, France

    Ferenc Molnar, Geological Survey of Finland

    M.S. Pandian, Pondicherry University, India

    Vasilios Melfos, Aristotle University of Thessaloniki,

    Greece

    Gheorghe Ilinca, University of Bucharest

    Mihai Marinescu, University of Bucharest

    Marcel Mărunţiu, Geological Institute of Romania,

    Bucharest

    Ioan Pintea, Geological Institute of Romania

    Mircea Ţicleanu, Geological Institute of Romania,

    Bucharest

    Nicolae Buzgar, "Alexandru Ioan Cuza" University,

    Iaşi

    Marian Munteanu, Geological Institute of Romania

    Ioan Seghedi, Institute of Geodynamics of the

    Romanian Academy, Bucharest

    Dan Stumbea, "Alexandru Ioan Cuza" University, Iaşi

    Sorin Silviu Udubașa, University of Bucharest

    Antonela Neacsu, University of Bucharest

    Călin Tămaş, Babeş-Bolyai University, Cluj-Napoca

    George Tudor, Geological Institute of Romania,

    Bucharest

    Rom . J. Mineral Deposits is also the Bulletin of the Society of Economic Geology of Romania

    The authors are responsible for the ideas presented in the papers.

    ISSN 1220-5648

  • Geological Institute of Romania

    Society of Economic Geology of Romania

    Romanian Journal of

    MINERAL DEPOSITS

    ISSN 1220-5648 VOL. 90 No. 1-2

    CONTENT

    Sergiu DRĂGUŞANU, Călin Gabriel TĂMAŞ

    New geological data on Văidoaia mining field, Roşia Montană Au-Ag epithermal deposit,

    Apuseni Mountains, Romania ............................................................................................................ 1

    Robert SZABO, Gheorghe C. POPESCU

    Preliminary data on secondary copper minerals from the Şiglău-Uricani perimeter,

    Vîlcan Mountains, Romania ............................................................................................................. 19

    Paulina HÎRTOPANU, Robert J. FAIRHURST, Gyula JAKAB, Sorin Silviu UDUBAŞA

    Monazite-(Ce) and its associations from the Ditrau alkaline intrusive massif,

    East Carpathians, Romania ............................................................................................................... 27

    Ioan PINTEA, Elena Luisa IATAN

    The magmatic-hydrothermal history of the β-quartz polymorphs from Roşia Montană

    dacite inferred by solid-, melt-, and fluid inclusion assemblages .................................................... 41

  • Rom. J. Mineral Deposits, vol. 90 (2017), No. 1-2, p. 1-18

    1

    NEW GEOLOGICAL DATA ON VĂIDOAIA MINING FIELD,

    ROŞIA MONTANĂ Au-Ag EPITHERMAL DEPOSIT,

    APUSENI MOUNTAINS, ROMANIA

    Sergiu DRĂGUŞANU1, Călin Gabriel TĂMAŞ1* ¹Department of Geology, Babeş-Bolyai University, 1, Kogălniceanu Street, 400084 Cluj-Napoca, Romania.

    *[email protected]

    Abstract: Văidoaia mining field is located in the north-eastern part of Roșia Montană low to intermediate sulfidation

    Au-Ag ore deposit, Apuseni Mountains, Romania. Significant traces of old mining works are visible within this

    perimeter at the surface and are partially still accessible in the underground. They are testifying an intense mining

    activity once. However, very limited geological and ore deposit data are available for this perimeter from previous

    studies. The country rocks from Văidoaia massif consist of Cretaceous sedimentary rocks (sandstones), vent breccia,

    and a dacite lava flow remnant. Adularia-sericite and silicification are the characteristic hydrothermal alterations. The

    K-alteration is represented by two types of adularia, i) adularia I formed by K-metasomatosis of the magmatic feldspar

    phenocrysts from dacite (lava flow and clasts within vent breccia), and ii) adularia II deposited from the hydrothermal

    fluids as euhedral to subhedral crystals together with hydrothermal quartz. White mica is occurring as small flakes on

    the adularised feldspar phenocrysts or in dacite groundmass. Silicification occurs within the groundmass of the dacite

    rocks and within the matrix of vent breccia. Hydrothermal quartz veinlets and vugs infillings are also quite frequent

    in dacite and vent breccia. Different styles of primary mineralizations occur, i.e. disseminated, stockworks, veins and

    breccia dykes. The disseminations were controlled by the porosity of the rocks (vent breccia), the stockworks are

    occurring along the contacts between vent breccia and Cretaceous flysch, while the veins are represented by small

    sized quartz structures hosted mainly by the vent breccia. The most important ore bodies are represented by several

    breccia dyke structures, five of them creating a parallel system striking WWN-EES with a steep S dip, and another

    one up to 50 cm width, which is heading NNE and has a dip of 70° towards WWN. These breccia dykes were the

    main exploitation targets in Văidoaia mining field. The mineralogy of the ore is very simple, with pyrite, gold and

    traces of chalcopyrite. The largest gold grain identified so far is measuring 80 micrometers. The gangue minerals are

    represented by quartz, calcite, and adularia II. At least two hydrothermal brecciation events were noticed. These

    brecciation events triggered the deposition of a black hydrothermal cement rich in organic matter known by the local

    miners as chinga, and of gold. The mineralizations from Văidoaia massif are typical low-sulfidation.

    Keywords: Roșia Montană, Văidoaia, epithermal mineralization, hydrothermal alterations, breccia structures, gold

    1. INTRODUCTION

    The Roşia Montană ore deposit is the largest gold deposit in Europe (Manske et al., 2006). The ore

    deposit is located in the Apuseni Mountains, west-central Romania (Fig. 1), in the north-western part of the

    Golden Quadrilateral - the most important historical gold mining region of Romania.

    Roşia Montană is a typical epithermal deposit. It was interpreted as a low to intermediate sulfidation

    Au-Ag deposit (Leary et al., 2004; Manske et al., 2006; Tămaş, 2010) related to a Neogene maar-diatreme

    complex (Tămaș, 2010).

    At the ore deposit scale several mining fields were separated, the most important being Cetate,

    Cârnic, Orlea, and Ţarina. Two smaller and less known mining fields exist in the eastern and north-eastern