The Reocín mine in northern Spain’s Basque-Cantabrian basin exploited a world-class Mississippi V... more The Reocín mine in northern Spain’s Basque-Cantabrian basin exploited a world-class Mississippi Valley-type Zn-Pb deposit. Its epigenetic mineralization is in Urgonian 116 ± 1 Ma dolomitized limestones of the Santillana syncline, which was formed by Oligocene and mid Miocene pulses of the Pyrenean orogeny. Paleomagnetic results (22 sites, 274 specimens) in mineralization isolated a stable remanence (ChRM) in pyrrhotite and minor magnetite inclusions in ore specimens, Zn concentrate, and tailings. A fold test shows that the ChRM is substantially post-folding. The mineralization’s paleopole lies on the European apparent polar wander path and indicates that the mineralization was formed at 15 ± 10 Ma. We postulate that brines originated in underlying Triassic and Lower Cretaceous sedimentary rocks and were driven upward into the host rocks by the hydraulic gradient created by the nearby Asturian massif.
Located in the Basque-Cantabrian basin of northernmost Spain, the Reocin mine exploited one of th... more Located in the Basque-Cantabrian basin of northernmost Spain, the Reocin mine exploited one of the world
Geological Society, London, Special Publications, 1998
... 29 tion is epigenetic and substantially postdates kar-stification (Gregg et al. ... in the Tr... more ... 29 tion is epigenetic and substantially postdates kar-stification (Gregg et al. ... in the Trend has been correlated with MVT mineralization found in surrounding districts of the American midcontinent based on regional isotopic, geochemical and paragenetic studies (Leach & Rowan ...
Crustal heat flow can provide a strong mechanism for driving groundwater flow, particularly in su... more Crustal heat flow can provide a strong mechanism for driving groundwater flow, particularly in submarine basins where other mechanisms for driving pore fluid flow such as topography, compaction and crustal deformation are too weak or too slow to have a significant effect on disturbing conductive heat flow. Fault zones appear to play a crucial role in focusing fluid migration in basins, as inferred in ancient rocks by many examples of hydrothermal deposits of sediment-hosted ores worldwide. Many rift-hosted deposits of lead, zinc, and barite ore appear to have formed at or near the seafloor by focused venting of hot basinal fluids and modified seawater, although the geophysical nature of these systems is not so well known. For example, the upper Kuna Formation, a finely laminated, black, organic-rich siliceous mudstone and shale in the Western Brooks Range of northwest Alaska, is host to the largest resources of zinc yet discovered in the Earth's crust, containing ore reserves i...
The Reocín mine in northern Spain’s Basque-Cantabrian basin exploited a world-class Mississippi V... more The Reocín mine in northern Spain’s Basque-Cantabrian basin exploited a world-class Mississippi Valley-type Zn-Pb deposit. Its epigenetic mineralization is in Urgonian 116 ± 1 Ma dolomitized limestones of the Santillana syncline, which was formed by Oligocene and mid Miocene pulses of the Pyrenean orogeny. Paleomagnetic results (22 sites, 274 specimens) in mineralization isolated a stable remanence (ChRM) in pyrrhotite and minor magnetite inclusions in ore specimens, Zn concentrate, and tailings. A fold test shows that the ChRM is substantially post-folding. The mineralization’s paleopole lies on the European apparent polar wander path and indicates that the mineralization was formed at 15 ± 10 Ma. We postulate that brines originated in underlying Triassic and Lower Cretaceous sedimentary rocks and were driven upward into the host rocks by the hydraulic gradient created by the nearby Asturian massif.
Located in the Basque-Cantabrian basin of northernmost Spain, the Reocin mine exploited one of th... more Located in the Basque-Cantabrian basin of northernmost Spain, the Reocin mine exploited one of the world
Geological Society, London, Special Publications, 1998
... 29 tion is epigenetic and substantially postdates kar-stification (Gregg et al. ... in the Tr... more ... 29 tion is epigenetic and substantially postdates kar-stification (Gregg et al. ... in the Trend has been correlated with MVT mineralization found in surrounding districts of the American midcontinent based on regional isotopic, geochemical and paragenetic studies (Leach & Rowan ...
Crustal heat flow can provide a strong mechanism for driving groundwater flow, particularly in su... more Crustal heat flow can provide a strong mechanism for driving groundwater flow, particularly in submarine basins where other mechanisms for driving pore fluid flow such as topography, compaction and crustal deformation are too weak or too slow to have a significant effect on disturbing conductive heat flow. Fault zones appear to play a crucial role in focusing fluid migration in basins, as inferred in ancient rocks by many examples of hydrothermal deposits of sediment-hosted ores worldwide. Many rift-hosted deposits of lead, zinc, and barite ore appear to have formed at or near the seafloor by focused venting of hot basinal fluids and modified seawater, although the geophysical nature of these systems is not so well known. For example, the upper Kuna Formation, a finely laminated, black, organic-rich siliceous mudstone and shale in the Western Brooks Range of northwest Alaska, is host to the largest resources of zinc yet discovered in the Earth's crust, containing ore reserves i...
Uploads
Papers by David Leach