English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Zendy Open

Presents the pdf analysis as premium feature

PDF Analysis

Insights

Presents the summarisation as premium feature

Summarisation

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the zaia usage as premium feature

ZAIA

Zendy Tools

Zendy Plus

Presents the access of premium content as premium feature

Premium Content

Mineralogical and fluid-inclusion studies have been conducted on Mn-rich breccias from three low-sulfidation epithermal gold deposits, Cirotan (Indonesia), Orcopampa (Peru) and Cavnic (Romania). In these deposits, the manganiferous minerals occur within cockade breccias that precede most of the deposition of sulfide. Cockade breccias consist of a lithic or sulfide nucleus, a few centimeters across, encrusted by several concentric envelopes that can be subdivided into three successive zones . Each zone may be composed of several stacked sequences of deposition. The Mn minerals are mainly clustered within the internal pinkish zone close to the nucleus, that also comprises quartz, "adularia" and sparse sulfides. Within this Mn mineral zone, eac h sequence begins with the deposition of Mn silicate, close to the rhodonite end-member (MnSiO 3), that fully or partially grades into Mn carbonate, close to the rhodochrosite (MnCO3) end-member, before the deposition of the next sequence. The intermedi- ate zone (the quartz-sulfide zone) consists of quartz-sulfide sequences, with minor Mn silicates. Each sequence begins with fin e- grained quartz, indicating a high rate of nucleation, which becomes coarser grained and irregular at the end of the sequence. Chlorite and sulfides are associated with quartz at the end of this zone. The external zone of the cockades is characterized by comb quartz, associated with illite, calcite and, sparingly, manganoan dolomite. The mineralogical zonation illustrated by the cocka des expresses a general evolution of the depositional process with time, with a progressive Mn-depletion and Ca-enrichment. No kutnohorite has been observed. Fluid inclusions from the three zones are all two-phase aqueous inclusions (L + V). The fluid salinities are similar in all the deposits and do not exceed 2.6 wt% NaCl eq., the final comb quartz from Orcopampa excepted. Two isenthalpic boiling events are recorded in relation with brittle deformation. The replacement of rhodonite by rhodochrosite revealed in each sequence of the Mn mineral zone could result in a temperature drop in relation to these boiling events, which release CO2 and increase pH.

the canadian mineralogist

EPISODIC DEPOSITION OF Mn MINERALS IN COCKADE BRECCIA STRUCTURES IN THREE LOW-SULFIDATION EPITHERMAL DEPOSITS: A MINERAL STRATIGRAPHY AND FLUID-INCLUSION APPROACH