Page 21 - Geochemical Remote Sensing of The Sub-Surface
P. 21
XX Contents
Helium surveys in petroleum exploration ................................................................. 338
Helium surveys in geothermal resource exploration ................................................. 343
Helium in thermal waters and gases ...................................................................... 343
Helium surveys for geothermal resources ............................................................. 344
Helium associated with faults .................................................................................... 346
Faults as secondary sources of helium .................................................................. 346
Groundwater surveys ........................................................................................ 346
Soil gas surveys ................................................................................................ 348
Helium monitoring in earthquake prediction ........................................................ 349
Conclusions ............................................................................................................... 350
Migration of helium in the near-surface environment ........................................... 350
Application of helium surveys .............................................................................. 352
Chapter 11. Radon ........................................................................................................................ 353
W. Dyck and I.R. Jonasson
Introduction ............................................................................................................... 353
Physical and chemical properties of radon ................................................................ 354
Definitions ................................................................................................................. 356
Geochemistry of radon .............................................................................................. 357
Concentrations of radon and radium in natural environments ............................... 358
Disequilibrium in the uranium decay series .......................................................... 365
Emanation and mobility of radon .......................................................................... 367
Analytical methods .................................................................................................... 382
Principles of methods ............................................................................................ 383
Instantaneous mode ............................................................................................... 384
Semi-integrating mode .......................................................................................... 386
Fully-integrated mode ........................................................................................... 388
Field methods ............................................................................................................ 389
Determination of radon in natural waters .............................................................. 389
Determination of radon in soil emanations ........................................................... 391
Comparison studies and case histories ...................................................................... 392
Future needs .............................................................................................................. 394
Chapter 12. Mercury ..................................................................................................................... 395
G.R. Cart and J.R. Wilmshurst
Introduction ............................................................................................................... 395
Geochemistry of mercury .......................................................................................... 396
Behaviour of mercury in the primary environment ................................................... 399
Low temperature epithermal base-metal deposits ................................................. 399
Volcanogenic massive sulphide deposits ............................................................... 400
Sediment-hosted massive sulphide deposits ......................................................... 402
Gold deposits ........................................................................................................ 403
The role of metamorphism .................................................................................... 404
Behaviour of mercury in the secondary environment ................................................ 406
Outcropping mineral deposits in dry climates ....................................................... 406
Outcropping mineral deposits in wet climates ...................................................... 412
Blind and buried mineral deposits in dry climates ................................................ 417