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The Earth Inside and Out phần 5

Nhiều người đã không chắc chắn về đá granite như kết quả cuối cùng của sự khác biệt kết tinh.Lý thuyết của Bowen để lại một dấu ấn không thể phai nhòa trên petrology lửa hiện đại (Yoder 1979; Hargraves 1980). Lý thuyết của ông kết tinh phân đoạn, tất nhiên, | 146 BERNHARD FRITSCHER not active. Similar distinctions of metamorphic depth-zones were subsequently made in 1862 by Bernhard von Cotta 1808-1879 and - emphasizing a steady long-lasting pressure as the essential characteristic of the lower region - by Jakob Johannes Sederholm 1863-1934 in 1891 and Charles Richard van Hise 1857-1918 in 1904. Rosenbusch himself pointed to Joseph Durocher s 1817-1860 statement of a proportionate relation between the degree of contact metamorphism and the distance from the magmatic intrusion that had caused the transformation Durocher 1845-1846 . Notwithstanding these early anticipations it was not until Rosenbusch s detailed study of the Steiger Schiefer that the ideas of metamorphic zones and progressive metamorphism became more widespread among Earth scientists. Rosen-busch s well-known zones of gradually increasing contact metamorphism were see Fig. 1 1 the zone of spotted slates or phyllites Kno-tenthonschiefer with occasional contact minerals mainly chiastolite 2 the zone of spotted schists Knotenglimmer-schiefer - 3 and the zone of hornfelses which represented the highest degree of metamorphism in 1875 Rosenbusch had called this the zone of andalusite schists according to its characteristic mineral . One of Rosenbusch s most significant results was his observation that these zones were made up of just a few minerals such as quartz mica andalusite chiastolite and staurolite as well as though rarely cordierite garnet and pyroxene. Quartz was observed to occur in each zone as well as biotite whereas feldspars seemed to be completely lacking in these contact metamorphic rocks. Rosenbusch also emphasized the transformation of the calcareous components of the original rocks i.e. co2 was usually replaced by SiO2. Rosenbusch s work gave a strong impulse to studies of metamorphism. He was however also responsible for some of the later difficulties in establishing theoretical chemistry as a method of the study of metamorphism. In his .