Chapter 6
Hydrothermal Activity and Metalliferous
Deposits
Abstract The World’s major marine geological structures have been affected by
physical and chemical changes during and after their creation at spreading axes
and in intraplate regions where islands and seamounts are formed. These changes
are largely related to the penetration of the hydrosphere into the rigid lithosphere.
A chemical reaction between the hydrosphere (seawater) and the lithosphere
(rocks) in the presence of heat gives rise to hydrothermal fluid. The circulation of
this fluid is the main cause of the lithosphere’s transformation due to the alteration
(hydration) of metallic components from rocks and their subsequent precipitation
on the sea floor in the form of ore deposits. A theory about the existence of
hydrothermal discharge and metal deposits on the ocean floor was based on
geophysical constraints related to the Earth’s heat budget. The deficit of heat
discharge on spreading ridges was thought to be the result of a discharge of
hydrothermal fluid on the sea floor.
Hydrothermal activity is a by-product of volcanism. The alteration of rocks due the
circulation of hot fluid in the lithosphere gives rise to the precipitation of metallic
compounds such as iron, copper and zinc sulfides, and precious metals such as
gold and silver as well as other basic compounds, all of which can be utilized by
the world’s population. Land-based hydrothermal deposits were long known and
have been exploited since early periods of human presence. For example, Neanderthal people drew animal pictures with powdery ochreous compounds derived
from hydrothermal precipitates found on the uplifted site
Hydrothermal activity on the sea floor has been one of the scientific community’s interests since its discovery in 1968–1969 (Degens and Ross 1969).
Since the 1970s, we have seen actual evidence of hydrothermal fluid circulation
through the solid, porous lithospheric material, and this has been occurring since
the early formation of our planet. The three main factors governing a hydrothermal system are the presence of a heat source and water, and also the permeability of nearby rocks. Solid Earth’s permeability is an important factor
related to the degree of lithospheric fissuring and fracturing as well as to the
various types of rock formations. For example, pyroclasts, hyaloclastites and
tectonic breccias form incoherent, randomly piled-up deposits, which enhance an
R. Hekinian, Sea Floor Exploration, Springer Oceanography,
DOI: 10.1007/978-3-319-03203-0_6,
Ó Springer International Publishing Switzerland 2014
145
Hydrothermal Activity and Metalliferous
Deposits
Abstract The World’s major marine geological structures have been affected by
physical and chemical changes during and after their creation at spreading axes
and in intraplate regions where islands and seamounts are formed. These changes
are largely related to the penetration of the hydrosphere into the rigid lithosphere.
A chemical reaction between the hydrosphere (seawater) and the lithosphere
(rocks) in the presence of heat gives rise to hydrothermal fluid. The circulation of
this fluid is the main cause of the lithosphere’s transformation due to the alteration
(hydration) of metallic components from rocks and their subsequent precipitation
on the sea floor in the form of ore deposits. A theory about the existence of
hydrothermal discharge and metal deposits on the ocean floor was based on
geophysical constraints related to the Earth’s heat budget. The deficit of heat
discharge on spreading ridges was thought to be the result of a discharge of
hydrothermal fluid on the sea floor.
Hydrothermal activity is a by-product of volcanism. The alteration of rocks due the
circulation of hot fluid in the lithosphere gives rise to the precipitation of metallic
compounds such as iron, copper and zinc sulfides, and precious metals such as
gold and silver as well as other basic compounds, all of which can be utilized by
the world’s population. Land-based hydrothermal deposits were long known and
have been exploited since early periods of human presence. For example, Neanderthal people drew animal pictures with powdery ochreous compounds derived
from hydrothermal precipitates found on the uplifted site
Hydrothermal activity on the sea floor has been one of the scientific community’s interests since its discovery in 1968–1969 (Degens and Ross 1969).
Since the 1970s, we have seen actual evidence of hydrothermal fluid circulation
through the solid, porous lithospheric material, and this has been occurring since
the early formation of our planet. The three main factors governing a hydrothermal system are the presence of a heat source and water, and also the permeability of nearby rocks. Solid Earth’s permeability is an important factor
related to the degree of lithospheric fissuring and fracturing as well as to the
various types of rock formations. For example, pyroclasts, hyaloclastites and
tectonic breccias form incoherent, randomly piled-up deposits, which enhance an
R. Hekinian, Sea Floor Exploration, Springer Oceanography,
DOI: 10.1007/978-3-319-03203-0_6,
Ó Springer International Publishing Switzerland 2014
145