Petrologic, structural, and age relations of serpentinite, amphibolite, and blueschist in the Shuksan Suite of the Iron Mountain–Gee Point area, North Cascades, Washington

The importance of talc and chlorite “hybrid” rocks for volatile recycling through subduction zones; evidence from the high-pressure subduction mélange of New Caledonia

“…This information, together with the common occurrence of talcand chlorite-rich rocks in other high-P terranes that represent exhumed subducted slab (e.g. Brown et al 1982;Sorensen and Grossman 1993;Widmer 1996;Pfiffner and Trommsdorff 1998;Katzir et al 2000;Maekawa et al 2004;Beane and Liou 2005;Marschall et al 2006) supports the suggestion of King et al (2006) that mélange and hybrid rock formation commonly occurs in subduction zones. Moreover, nearly pure talc and chlorite schists formed during seafloor hydrothermal processes (e.g., Bach et al 2004;Boschi et al 2006) will also end up as components of subducting slabs.…”

“…Nearly pure talc and/or chlorite rocks have also been recovered during drilling and dredging of ocean floor spreading centres and hydrothermal vents (Lonsdale et al 1980;Hannington et al 2001;Bach et al 2004;D'Orazio et al 2004;Boschi et al 2006). Blackwall rocks also occur in many high-P metamorphic terranes [e.g., Cyclades, Greece (Katzir et al 2000;Marschall et al 2006); Sanbagawa Belt, Japan (Maekawa et al 2004); Central Alps (Widmer 1996;Pfiffner and Trommsdorff 1998); Maksyotov Complex, Russia (Beane and Liou 2005); Catalina Schist, California (Sorensen and Grossman 1989;Bebout 1991;Bebout and Barton 2002;King et al 2006); Franciscan Complex, California (King et al 2003); and the Shuksan Suite, Washington (Brown et al 1982;Sorensen and Grossman 1993)], but these rocks are rarely subject to detailed scientific study. Exceptions include the high-P terranes of Washington, California and Japan by Grossman (1989, 1993), Bebout and Barton (2002), King et al (2003King et al ( , 2006 and Maekawa et al (2004).…”

Polymetamorphism of Aktyuz eclogites (northern Kyrgyz Tien-Shan) deduced from inclusions in garnets

“…The first event was a relatively low to medium P/T amphibolite or epidote amphibolite facies metamorphism. This kind of relatively low P/T type event before eclogitic metamorphism has been described from Sambagawa eclogites in Japan (Miyagi and Takasu, 2005), and may be attained at the metamorphic sole of ophiolites (Brown et al, 1982;Wakabayashi, 1990;Dilek and Whitney, 1997). These studies suggest that the precursor low to medium pressure event was probably caused by the heat from a hot hanging wall at the inception of subduction.…”

Blueschists and Eclogites of the World and Their Exhumation

“…than the surrounding 105-to 130-Ma schists (Misch, 1963(Misch, , 1964Haugerud et al, 1981;Brown et al, 1982). A U-Pb age of 163.5 Ma for a single zircon separated from Shukusan diorite (N. Walker, Univ.…”

“…Protoliths constitute a subduction-zone complex, and were metamorphosed in a near-arc setting. Metamorphic rocks grade from the PA, GS/BS transition to epidoteamphibolite facies; P/T conditions are estimated at T = 330-400° C and P = 7 kbar, with slightly higher P and T calculated for garnet amphibolite (Brown et al, 1982;Brown, 1986). K-Ar ages of muscovite and hornblende separated from amphibolite-facies rocks range from 144 to 164 Ma (Armstrong, 1980), and are older 496 MARUYAMA ET AL.…”