The kinematic evolution of the Nepalese Himalaya interpreted from Nd isotopes

Integrated tectonostratigraphic analysis of the Himalaya and implications for its tectonic reconstruction

“…3 and 4) eliminates the basis for reconstruction of the GH as an accreted tectonic terrane [7,8]. DeCelles et al's [7] claim, that the TH was deposited as a result of uplift related to the latest Cambrian^earliest Fig.…”

“…The accreted terrane model [7] is based on published detrital zircon age spectra of the GH and TH that show a wide range of Precambrian to Late Cambrian zircons, in contrast to LH bedrock samples that contain zircons exclusively older than 1.6 Gyr. These data, combined with a similar distribution of Nd model ages for sedimentary rocks, suggested that the LH is, en masse, characterized by older detrital materials than the two northern lithotectonic zones [7,8]. Samples of Cenozoic syn-orogenic molasse and modern stream sediment from the LH have been interpreted based on this idea, i.e., younger 5001 400 Ma grains as having been derived solely from the GH or TH [9,10].…”

Tectonic interleaving along the Main Central Thrust, Sikkim Himalaya

“…The Lesser Himalayan Sequence is a Palaeoproterozoic metasedimentary sequence with an ε Nd(0) signature of -20 to -25 that has been intruded by c. 1.8 Ga granites. In contrast, the Greater Himalayan Sequence is a younger, Neoproterozoic-Ediacaran (and possibly Palaeozoic) sequence of metasedimentary rocks, characterized by an ε Nd(0) signature of -15 to -20, indicative of younger source regions, typically intruded by younger, c. 500 Ma and subordinate c. 830 Ma granites (Parrish & Hodges 1996;Ahmad et al 2000;Robinson et al 2001;Martin et al 2005Martin et al , 2011Richards et al 2005;Imayama & Arita 2008;Gehrels et al 2011;Long et al 2011b;Tobgay et al 2010;McQuarrie et al 2013;Webb et al 2013).…”

“…A variety of factors have caused controversy over the Main Central Thrust: the divergent criteria used to define the thrust, differences in methods and approach, and variations in appearance of the thrust in the field (Searle et al 2008, and references therein). Different criteria used to define the thrust include the following: (1) lithological changes (Heim & Gansser 1939;Valdiya 1980;Gansser 1983;Pêcher 1989;Davidson et al 1997;Daniel et al 2003;Tobgay et al 2012); (2) high strain in a distinct zone (Stephenson et al 2001;Gupta et al 2010); (3) metamorphic discontinuities (Bordet 1961;Le Fort 1975;Hubbard & Harrison 1989;Stäubli 1989;Harrison et al 1997;Catlos et al 2001;Kohn et al 2001;Daniel et al 2003;Groppo et al 2009;Martin et al 2010); (4) structural criteria (Pêcher 1989;Martin et al 2005;Searle et al 2008); (5) isotopic breaks (Inger & Harris 1993;Parrish & Hodges 1996;Whittington et al 1999;Ahmad et al 2000;Robinson et al 2001;Martin et al 2005Martin et al , 2011Richards et al 2005Richards et al , 2006Ameen et al 2007;Imayama & Arita 2008;Gehrels et al 2011;Long et al 2011b;Tobgay et al 2010;McQuarrie et al 2013;…”

Typecasting prospective Au-bearing sedimentary lithologies using sedimentary geochemistry and Nd isotopes in poorly exposed Proterozoic basins of the Tanami region, Northern Australia

“…Condie and Wronkiewicz (1990) concluded that the Cr/Th ratio in pelites can provide an important geochemical index of early Precambrian crustal evolution and can be used to monitor changes in source composition with strong correlations to Th/Sc, Sc/Th and La/Sc ratios. The use of rare earth elements (REE) as provenance indicators requires assumptions to be met; (1) they are not significantly modified by metamorphism and diagenesis (Michard 1989;Bau 1991), and (2) that the REE were quantitatively transported in the detrital component (McLennan and Taylor 1982;Crichton and Condie 1993;Ugidos et al 1997;Robinson et al 2001). …”