A zone in ore deposits consisting of the top of Lindgren's mesothermal zone and the bottom of the epithermal zone. 2, fiche 1, Anglais, - leptothermal
Record number: 1, Textual support number: 1
CONT
... epigenetic-hydrothermal deposits are classified according to their depth and temperature of formation - hypothermal deposits being deep-seated high temperature deposits; mesothermal deposits those formed at low temperatures and medium depths, and, thirdly, epithermal, near-surface deposits. Later terms include leptothermal to cover deposits gradational from mesothermal to epithermal, and telethermal for very low-temperature deposits formed at great distances from the source of the hydrothermal solutions which gave rise to them. 3, fiche 1, Anglais, - leptothermal
Record number: 1, Textual support number: 1
OBS
leptothermal ... Mineral grain size averages smaller and more variable than in mesothermal ores. There is an increased development of vugs toward the shallower limit of the zone. Rock alteration varies from sericitic to propylitic. Vertical depth range is estimated from 10,000 to 15,000 feet. 2, fiche 1, Anglais, - leptothermal
On sépare quelquefois un type «leptothermal», qui correspond à la partie supérieure du mésothermal, sans posséder franchement les caractéristiques épithermales. Les textures rubanées et drusiques y sont plus développées que dans le mésothermal; le grain plus irrégulier. 1, fiche 1, Français, - leptothermal
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