Digital Database of Modern Evaporites and their Predicted Distribution Based on Results...
163
Zerzan (1989) published a FORTRAN program (overlap) to calculate the area
of two overlapping, 2-dimensional polygons. The algorithm was converted to
the C-programming language, by J. Kleypas (NCAR, Boulder, CO) and was revised by CNW to calculate the area of overlap between a digitized polygon and
the present lOx 1 0 grid of latitude and longitude.
Appendix II: Regional Aspects of the Modern Evaporite Distribution
The majority of modern evaporite forming environments in the Americas are
saline pans and saline mud flats (Fig. IB, lC). These occur primarily in the rain
shadow and intermontane basins along the western margin of the north-southtrending continental divide formed by the Rocky and Andes Mountains. The
largest concentration of evaporites is in South America (Fig. 1). There are a large
number of saline pans and mud flats in Argentina, Bolivia, and Chile. These occur predominantly in the rain shadow along the eastern side of the Andes. This
is an example of an alluvial fan-saline pan sub environment, where saline pans
and mud flats are surrounded by alluvial fans extending from mountain flanks
(Smoot and Lowenstein 1991). The northernmost salt-forming body in the
Americas, is the Great Salt Lake in Utah (Fig. lC), where there are saline pans,
mud flats and solar salt operations surrounding a perennial saline lake. There
are a few marginal marine salinas around the Gulf of California and on the coast
of the Gulf of Mexico (Fig. ID). There are also marginal marine sabkhas on the
southeastern margin of Argentina between the Colorado and Parana Rivers
(Fig. ID). In Central America, the Caribbean and Brazil, salt is produced by the
solar evaporation of seawater (Fig. 2).
All of the present-day salt-producing areas in Europe are solar salt operations
(Fig. 2). The majority of modern evaporites in Africa, are saline pans and mud flats
in the northwestern part of the continent (Fig.lB). These evaporites have accumulated in local depressions between eolian dunes and are fed by ephemeral streams.
The primary source of salt for human consumption south of the equator in Africa,
comes from widely distributed solar salt operations (Fig. 2). The largest evaporiteaccumulating areas on the Arabian subcontinent are marginal marine sabkhas in
the United Arab Emirates and Abu Dhabi on the southwest side of the Persian Gulf
(Fig. ID). There are a few saline pans and mud flats in Syria and northern Iraq.
There are some saline lakes in the intermontane basins in Turkey (between the
Mediterranean and Black Seas) and a few sabkhas adjacent to the Black Sea. The
depression around the northern part of the Caspian Sea is covered with salt lakes,
saline pans, and saline mud flats. The mountainous region south of the Caspian
depression has widely distributed saline pans and saline mud flats (Fig.lB).
In China and the region of the former Soviet Union, there are a large number
of saline lakes (Fig. lC). This was the only region covered by the AMS (19341965) maps that explicitly differentiated between saline lakes and saline pans.
The existence of so many saline lakes is probably due in large part, to dissolution
by groundwater and rivers of pre-Holocene evaporite deposits. The former Soviet Union contains some of the world's largest halite deposits (Lefond 1969).
163
Zerzan (1989) published a FORTRAN program (overlap) to calculate the area
of two overlapping, 2-dimensional polygons. The algorithm was converted to
the C-programming language, by J. Kleypas (NCAR, Boulder, CO) and was revised by CNW to calculate the area of overlap between a digitized polygon and
the present lOx 1 0 grid of latitude and longitude.
Appendix II: Regional Aspects of the Modern Evaporite Distribution
The majority of modern evaporite forming environments in the Americas are
saline pans and saline mud flats (Fig. IB, lC). These occur primarily in the rain
shadow and intermontane basins along the western margin of the north-southtrending continental divide formed by the Rocky and Andes Mountains. The
largest concentration of evaporites is in South America (Fig. 1). There are a large
number of saline pans and mud flats in Argentina, Bolivia, and Chile. These occur predominantly in the rain shadow along the eastern side of the Andes. This
is an example of an alluvial fan-saline pan sub environment, where saline pans
and mud flats are surrounded by alluvial fans extending from mountain flanks
(Smoot and Lowenstein 1991). The northernmost salt-forming body in the
Americas, is the Great Salt Lake in Utah (Fig. lC), where there are saline pans,
mud flats and solar salt operations surrounding a perennial saline lake. There
are a few marginal marine salinas around the Gulf of California and on the coast
of the Gulf of Mexico (Fig. ID). There are also marginal marine sabkhas on the
southeastern margin of Argentina between the Colorado and Parana Rivers
(Fig. ID). In Central America, the Caribbean and Brazil, salt is produced by the
solar evaporation of seawater (Fig. 2).
All of the present-day salt-producing areas in Europe are solar salt operations
(Fig. 2). The majority of modern evaporites in Africa, are saline pans and mud flats
in the northwestern part of the continent (Fig.lB). These evaporites have accumulated in local depressions between eolian dunes and are fed by ephemeral streams.
The primary source of salt for human consumption south of the equator in Africa,
comes from widely distributed solar salt operations (Fig. 2). The largest evaporiteaccumulating areas on the Arabian subcontinent are marginal marine sabkhas in
the United Arab Emirates and Abu Dhabi on the southwest side of the Persian Gulf
(Fig. ID). There are a few saline pans and mud flats in Syria and northern Iraq.
There are some saline lakes in the intermontane basins in Turkey (between the
Mediterranean and Black Seas) and a few sabkhas adjacent to the Black Sea. The
depression around the northern part of the Caspian Sea is covered with salt lakes,
saline pans, and saline mud flats. The mountainous region south of the Caspian
depression has widely distributed saline pans and saline mud flats (Fig.lB).
In China and the region of the former Soviet Union, there are a large number
of saline lakes (Fig. lC). This was the only region covered by the AMS (19341965) maps that explicitly differentiated between saline lakes and saline pans.
The existence of so many saline lakes is probably due in large part, to dissolution
by groundwater and rivers of pre-Holocene evaporite deposits. The former Soviet Union contains some of the world's largest halite deposits (Lefond 1969).