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Amphibole compositions and metamorphic history of the Rand Schist and the greenschist unit of the Catalina Schist, Southern California

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The Catalina Schist and Rand Schist are two high P/T terranes in southern California. The Catalina Schist is correlated with the Franciscan Complex and occurs in the continental borderland. It consists of a blueschist-facies melange tectonically overlain by a “greenschist” unit, which, in turn, is overthrust by an amphibolite unit. The greenschist unit itself is inversely zoned from epidote-amphibolite fades at the top through greenschist facies in the center to transitional blueschist-greenschist facies at the base. The Rand Schist is part of the eugeoclinal Pelona-Orocopia Schist terrane, which lies interior to the present continental margin, structurally beneath Precambrian to Mesozoic sialic basement. The Rand Schist is inversely zoned from epidote-amphibolite facies to transitional blueschist-greenschist facies, similar to the greenschist unit of the Catalina Schist.

Two trends in amphibole composition, one from actinolite to hornblende in greenschists and epidote amphibolites (calcic series) and the other from actinolite through winchite to crossite in glaucophanic greenschists (sodic-calcic series), are present in both the Rand Schist and the greenschist unit of the Catalina Schist. The transition from actinolite to hornblende in the calcic series is defined by increases in tschermakite, edenite, and glaucophane substitution. Amphiboles of the sodic-calcic series differ mainly in the degree of glaucophanic substitution. The similarity of amphibole trends in the two terranes indicates that they were metamorphosed at approximately the same pressures and temperatures, and is evidence that the Rand Schist originated in a subduction zone, despite its present intracontinental setting.

Most glaucophanic greenschists in the Rand and Catalina Schists contain both a sodic and a calcic member of the sodic-calcic series. Textural relations indicate that calcic members generally developed after the sodic ones. This implies that sodic amphibole formerly may have been present in many of the structurally higher greenschists and epidote amphibolites. Preservation of the inverted zonations, as well as microstructural evidence for the syntectonic development of calcic and sodic-calcic amphiboles, suggest that glaucophanic greenschists, greenschists, and epidote amphibolites all formed during underthrusting (subduction). This contrasts with many orogenic belts, where replacement of blueschists by greenschists to amphibolites is attributed to thermal reequilibration during erosional unroofing.

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  1. Bailey EH (1941) Mineralogy, petrology, and geology of Santa Catalina Island. PhD thesis Stanford University

  2. Bennett V, De Paolo DJ (1982) Tectonic implications of Nd isotopes in the Pelona, Rand, Orocopia and Catalina Schists, southern California. Geol Soc Am Abstr Progr 14:442

  3. Brown EH (1974) Comparison of the mineralogy and phase relations of blueschists from the North Cascades, Washington, and greenschists from Otago, New Zealand. Bull Geol Soc Am 85:333–344

  4. Brown EH (1977) The crossite content of Ca-amphibole as a guide to pressure of metamorphism. J Petrol 18:53–72

  5. Burchfiel BC, Davis GA (1981) Mojave Desert and environs. In: Ernst WG (ed) The geotectonic development of California, Rubey vol 1. Prentice-Hall, Englewood Cliffs, New Jersey, pp 217–252

  6. Cooper AF (1972) Progressive metamorphism of metabasic rocks from the Haast Schist Group of Southern New Zealand. J Petrol 13:457–492

  7. Crowell JC (1968) Movement histories of faults in the Transverse Ranges and speculations on the tectonic history of California. In: Dickinson WR, Grantz A (eds) Proceedings of conference on geologic problems of San Andreas fault system. Stanford University Publications, Geol Sci 11:323–341

  8. Crowell JC (1981) An outline of the tectonic history of southeastern California. In: Ernst WG (ed) The geotectonic development of California, Rubey vol 1. Prentice-Hall, Englewood Cliffs, New Jersey, pp 583–600

  9. Dungan MA, Vance JA, Blanchard DP (1983) Geochemistry of the Shuksan greenschists and blueschists, North Cascades, Washington: variably fractionated and altered metabasalts of oceanic affinity. Contrib Mineral Petrol 82:131–146

  10. Ehlig PL (1958) The geology of the Mount Baldy region of the San Gabriel Mountains, California. PhD thesis University of California, Los Angeles

  11. Ehlig PL (1968) Causes of distribution of Pelona, Rand, and Orocopia Schists along the San Andreas and Garlock faults. In: Dickinson WR, Grantz A (eds) Proceedings of conference on geologic problems of San Andreas fault system. Stanford University Publications, Geol Sci 11:294–306

  12. Ehlig PL (1981) Origin and tectonic history of the basement terrane of the San Gabriel Mountains, central Transverse Ranges. In: Ernst WG (ed) The geotectonic development of California, Rubey vol 1. Prentice-Hall, Englewood Cliffs, New Jersey

  13. England PC (1978) Some thermal considerations of the Alpine metamorphism-past, present and future. Tectonophys 46:21–40

  14. England PC, Richardson SW (1977) The influence of erosion upon the mineral facies of rocks from different metamorphic environments. J Geol Soc London 134:201–213

  15. Ernst WG (1973) Interpretive synthesis of metamorphism in the Alps. Bull Geol Soc Am 84:2053–2078

  16. Ernst WG (1979) Coexisting sodic and calcic amphiboles from high-pressure belts and the stability of barroisitic amphibole. Mineral Mag 43:269–278

  17. Ernst WG, Seki Y, Onuki H, Gilbert MC (1970) Comparative study of low-grade metamorphism in California Coast Ranges and the Outer Metamorphic Belt of Japan. Mem Geol Soc Am 124, p 276

  18. Graham CM (1974) Metabasite amphiboles of the Scottish Dalradian. Contrib Mineral Petrol 47:165–185

  19. Graham CM (1975) Inverted metamorphic zonation and mineralogy of the Pelona Schist, Sierra Pelona, Transverse Ranges. Geol Soc Am Abstr with Progr 7:321–322

  20. Graham CM, England PC (1976) Thermal regimes and regional metamorphism in the vicinity of overthrust faults: an example of shear heating and inverted metamorphic zonation from southern California. Earth Planet Sci Letters 31:142–152

  21. Graham CM, Powell R (1984) A garnet-hornblende geothermometer: calibration, testing, and application to the Pelona Schist, southern California. J Metamorphic Geol 2:13–31

  22. Gray JR, Yardley BWD (1979) A Caledonian blueschist from the Irish Dalradian. Nature 278:736–737

  23. Haxel G, Dillon J (1978) The Pelona-Orocopia Schist and Vincent-Chocolate Mountain thrust system, southern California. In: Howell DG, McDougall KA (eds) Mesozoic paleogeography of the western United States. Soc Econ Paleo Mineral, Pacific Sect, pp 453–469

  24. Haugerud RA, Morrison ML, Brown EH (1981) Structural and metamorphic history of the Shuksan metamorphic suite in the Mount Wilson and Gee Point areas, North Cascades, Washington. Bull Geol Soc Am 92:374–383

  25. Holland TJB, Richardson SW (1979) Amphibole zonation in metabasites as a guide to the evolution of metamorphic conditions. Contrib Mineral Petrol 70:143–148

  26. Jacobson CE (1983a) Structural geology of the Pelona Schist and Vincent thrust, San Gabriel Mountains, California. Bull Geol Soc Am 94:753–767

  27. Jacobson CE (1983b) Relationship of deformation and metamorphism of the Pelona Schist to movement on the Vincent thrust, San Gabriel Mountains, southern California. Am J Sci 283:587–604

  28. Jacobson CE (1983c) Complex refolding history of the Pelona, Orocopia, and Rand Schists, southern California. Geology 11:583–586

  29. Jacobson CE (1984) Petrological evidence for the development of refolded folds during a single deformational event. J Struct Geol 6:563–570

  30. Laird J, Albee AL (1981) High-pressure metamorphism in mafic schist from northern Vermont. Am J Sci 281:97–126

  31. Leake BE (1978) Subcommittee on amphiboles, IMA: Nomenclature of amphiboles. Mineral Mag 42:533–563

  32. Lister GS, Banga G, Feenstra A (1984) Metamorphic core complexes of Cordilleran type in the Cyclades, Aegean Sea, Greece. Geology 12:221–225

  33. Papike JJ, Cameron KL, Baldwin K (1974) Amphiboles and pyroxenes, characteristics of other than quadrilateral components and estimates of ferric iron from microprobe data. Geol Soc Am Abstr with Progr 6:1053–1054

  34. Platt JP (1975) Metamorphic and deformational processes in the Franciscan Complex, California: some insights from the Catalina Schist Terrain. Bull Geol Soc Am 86:1337–1347

  35. Platt JP (1976) The petrology, structure, and geologic history of the Catalina Schist Terrain, southern California. Univ Calif Pub in Geol Sci 112:1–111

  36. Postlethwaite CE (1983) The structural geology of the western Rand Mountains, northwestern Mojave Desert, California. MS thesis Iowa State University

  37. Postlethwaite CE, Jacobson CE (1982) Structural geology and metamorphic petrology of the Rand Schist, western Mojave Desert. Geol Soc Am Abstr Progr 14:225

  38. Postlethwaite CE, Jacobson CE (1986) Structures and metamorphism associated with the Rand thrust, Rand Mountains, northwestern Mojave desert, California. Submitted to J Struct Geol

  39. Sharry J (1981) The geology of the western Tehachapi Mountains, California. PhD thesis Massachusetts Inst Tech

  40. Sorensen SS (1984) Petrology of basement rocks of the California Continental Borderland and the Los Angeles Basin. PhD thesis University of California, Los Angeles

  41. Sorensen SS (1985) Comparative petrology and geochemistry of blueschist and greenschist facies rocks from the Catalina Schist terrane, southern California. Proceedings of the Penrose Conference on high-pressure metamorphism (in press)

  42. Suppe J, Armstrong RL (1972) Potassium-argon dating of Franciscan metamorphic rocks. Am J Sci 272:217–233

  43. Trzcienski WE Jr, Carmichael DM, Helmstaedt H (1984) Zoned sodic amphibole: petrologic indicator of changing pressure and temperature during tectonism in the Bathurst Area, New Brunswick, Canada. Contrib Mineral Petrol 85:311–320

  44. Woodford AO (1924) The Catalina metamorphic facies of the Franciscan Series. Univ Calif Pub Geol Sci 15:49–68

  45. Yardley BWD (1982) The early metamorphic history of the Haast schists and related rocks of New Zealand. Contrib Mineral Petrol 81:317–327

  46. Yeats RS (1968) Southern California structure, seafloor spreading, and history of the Pacific Basin. Bull Geol Soc Am 79:1693–1702

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Correspondence to C. E. Jacobson.

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Jacobson, C.E., Sorensen, S.S. Amphibole compositions and metamorphic history of the Rand Schist and the greenschist unit of the Catalina Schist, Southern California. Contr. Mineral. and Petrol. 92, 308–315 (1986). https://doi.org/10.1007/BF00572159

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  • Subduction
  • Continental Margin
  • Subduction Zone
  • Greenschist Facies
  • Amphibole Composition