This study from Oman concurs with existing literature that school dropout is common among children with ADHD. Concerted efforts are needed to mitigate this trend. Management strategies should incorporate the treatment of comorbid conduct disorder.
Several types of Ca-rich, metasomatically altered rocks occur as blocks or reaction zones in a serpentinite-matrix mélange in the Bawshir-Al-Khuwair area, west of Ruwi in northeastern Oman. Type A rodingites contain mainly hydrogarnet, with smaller amounts of diopside, tremolite ± pumpellyite ± prehnite. Type B rocks contain more diopside ± tremolite and smaller amounts of hydrogarnet. Type C nephrites consist chiefly of tremolite and have a distinctive botryoidal texture. Quartzite blocks in this mélange were also affected by Ca-metasomatism, and contain variable amounts of tremolite, hydrogarnet, chlorite, and clinozoisite.Relatively immobile trace and rare-earth element contents of these rocks suggest that the protoliths of types A and B metasomatic rocks were ocean-island basalts, whereas type C nephrites represent metasomatized serpentinites. Isocon diagrams show that all metasomatic rocks formed by the addition of Ca ± Mg ± volatiles, and leaching of almost all other elements to variable degrees. Field and textural relations interpreted with an activity-corrected petrogenetic grid in the system CMASH suggest that metasomatism took place in stages over a range of P-T conditions, beginning at 220-310°C and 3-6 kbar, and ending at 250-310°C, P < 3.2 kbar. Diffusion of Ca 2+ out of the serpentinizing peridotites into blocks of basalts and quartzites was the primary cause of early metasomatism, which overlapped with high P/T metamorphism of the same blocks. Infiltration of low-salinity aqueous fluids was partly responsible for the latest stages of metasomatism, which took place during exhumation, and continued after the final emplacement of the ophiolite. 1 Corresponding author; email: aelshazly@utm.edu 2 Abbreviations used in this paper are as follows: Act = actinolite; Ap = apatite, Cc = calcite, Chl = chlorite, Chr = chromite; Cpx = clinopyroxene; Czo = clinozoisite; Di = diopside, Dol = dolomite; E-MORB = enriched mid-ocean ridge basalts; Ep = epidote, Fe 2 O 3 * = total Fe-oxides expressed as Fe 2 O 3 , Gr = grossular; Gt = garnet, Mc = magnesite; Mgt = magnetite; Qz = quartz; Tc = talc; Hgt = hydrogarnet; Hrc = hercynite; Ill = illite; Jd = jadeite, Lw = lawsonite; OIB = ocean-island basalt; Ol = olivine; Opq = opaque phase; Opx = orthopyroxene; Oxychl = oxychlorite; Plag = plagioclase feldspar; Pmp = pumpellyite; Prh = prehnite; Sp = spinel; Srp = serpentine; Tc = talc; Tr = tremolite; Ttn = titanite. Downloaded by [Korea University] at 07:26 26 December 2014
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