The Elements of economic geology

Bibliographic data

Monograph

Identifikator:: 1773832379

URN:: urn:nbn:de:zbw-retromon-172798

Document type:: Monograph

Author:: Gregory, John W. http://d-nb.info/gnd/11683014X

Title:: The Elements of economic geology

Place of publication:: London

Publisher:: Methuen

Year of publication:: 1928

Scope:: XIV, 312 S.; graph. Darst.

Digitisation:: 2021

Collection:: Economics Books

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Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Part III. Earthy minerals

Collection:: Economics Books

210 ECONOMIC GEOLOGY INTRUSIVE SALT DEPOSITS AND SALT DoMEsS—Some salt deposits are of such enormous thickness that the simple evaporation of an inland sea does not explain them. Thus a bore near Berlin at Speerinburg—which is historic from its evidence as to the increase of underground temperature— passed through 3000 feet of rock-salt without reaching the bottom. To produce such a quantity would require the evaporation of seven times as much sea-water as covers the deepest part of the existing oceans. Moreover, some salt deposits, instead of occurring in horizontal sheets regularly interstratified with sediments, are intruded in tongues which have disturbed the adjacent beds and produced slipped and slicken-sided surfaces. These tongues gave rise to the theory that salt is sometimes of igneous origin, a view sup- ported by the abundant chlorine vapours emitted through volcanic vents. Dr. G. E. Pilgrim (Mem. G.S. Ind., xxxiv, 1909, p. 68) explains the salt at Kamarij near the Persian Gulf as due to the injection of a volcanic magma of sodium chloride. The aqueous theory has the recommendation that though salt deposits occur at many different periods in the earth's history their constant association with red beds or limestones of an abnormal character indicates their deposition in lagoons. They thus occur in the Cambrian in the salt range of India and in Persia; in the Devonian of Russia and the United States; in the red beds of the Permian and Triassic Systems in England, Germany, and the United States; and in Kainozoic beds in Eastern Europe, Persia;and Somaliland. The abnormal thickness of salt deposits can be explained by aqueous deposition by the ‘“ bar theory” of Ochsenius, which may be illustrated from the Caspian Sea. That sea has no connection with the ocean and receives at its northern end the waters of the Volga and Ural Rivers. The southern end is bordered by dry steppes and the evaporation during the dry season is high. Karabugas, an extensive basin on the eastern shore, is connected with the Caspian by shallow channels, through which the inflow to replace the water lost by evaporation introduces 3500 tons of salt a day. The change produced in the Caspian water is illustrated by two analyses quoted from A. C. Clarke (Data of Geochemistry, 1924, p. 169) :—

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