Stassfurt Salt-Bearing Basin

(also Stassfurt Basin), a section of the Upper Permian (Zechstein) Western European Basin, located within the German Democratic Republic and the Federal Republic of Germany. In the broad sense, the term is sometimes used as a synonym for the Western European Salt-bearing Basin, which stretches from Great Britain to the northwestern USSR. The salt-bearing deposits also continue beneath the North Sea.

The Stassfurt Basin covers an area of 1–1.2 million sq km. It stretches for more than 1,600 km from west to east in a band measuring 300 to 600 km in width. The thickness of the salt-bearing deposits reaches 1,200–1500 m. The basin includes geological reserves of rock salt, which, according to overall estimates amount to 1.5 × 10⁵ cu km, or 3 × 10¹⁴ tons, and potassium salts, with estimated reserves of 135 billion tons of K₂O). Potassium salts account for its major industrial importance.

The rock salt of the Stassfurt Basin has been known since the beginning of the Middle Ages; the potassium salts were discovered in 1857. The Zechstein salt-bearing deposits are subdivided stratigraphically into five series (in ascending order): Werra, Stassfurt, Leine, Aller, and Ohre. Blanket deposits of potassium salts are found in the three lowest series. There are eight such deposits in the Werra and Northeastern German depressions, five of which are exploited by the German Democratic Republic and the Federal Republic of Germany. The deposition conditions of the strata range from nearly horizontal to complex salt dome formations. The thickness of the strata ranges from 2 to 35–40 m, and the depth at which the deposits occur, from 300 to 1,500–2,000 m. Mining work is carried out at depths of 400 to 1,000 m (rarely to 1,200 m). The Stassfurt stratum is the largest, occupying an area of at least 80,000 sq km.

The potassium deposits are of the sulfate type and contain more than 20 sulfate and chloride potassium and potassium-magnesium minerals. Kieserite-containing sylvinite (hartsalz), mixed potassium-magnesium salts, and carnallite rocks are the major products. The K₂O content in the salts mined is 10–18 percent. The mining of rock salt is carried out by underground methods (in mines) or by leaching through drilled wells. Potassium salts are worked in mines in the German Democratic Republic and the Federal Republic of Germany. In 1974, 2.8 and 2.6 million tons of potassium salts (with respect to K₂O content) were produced in the German Democratic Republic and the Federal Republic of Germany, respectively.