Abstract :
Xu et al. (2003) [Xu, T., Sonnenthal, E., Bodvarsson, G., 2003. A reaction-transport model for calcite precipitation and evaluation of infiltration–percolation fluxes in unsaturated fractured rock. J. Contam. Hydrol., 64, 113–127.] presented results of a reaction-transport model for calcite deposition in the unsaturated zone at Yucca Mountain, and compared the model results to measured abundances in core from a surface-based borehole. Marshall et al. (2003) [Marshall, B.D., Neymark, L.A., Peterman, Z.E., 2003. Estimation of past seepage volumes from calcite distribution in the Topopah Spring Tuff, Yucca Mountain, Nevada. J. Contam. Hydrol., 62–63, 237–247.] used the calcite distribution in the Topopah Spring Tuff to estimate past seepage into lithophysal cavities as an analog for seepage into the potential repository waste emplacement drifts at Yucca Mountain in southern Nevada (USA). Dublyansky and Smirnov (2005) [Dublyansky, Y.V., Smirnov, S.Z., 2005. Commentary: assessment of past infiltration fluxes through Yucca mountain on the basis of the secondary mineral record—is it a viable methodology? J. Contam. Hydrol. (this issue).] wrote a commentary paper to Marshall et al. (2003) [Marshall, B.D., Neymark, L.A., Peterman, Z.E., 2003. Estimation of past seepage volumes from calcite distribution in the Topopah Spring Tuff, Yucca Mountain, Nevada. J. Contam. Hydrol., 62–63, 237–247.] and Xu et al. (2003) [Xu, T., Sonnenthal, E., Bodvarsson, G., 2003. A reaction-transport model for calcite precipitation and evaluation of infiltration–percolation fluxes in unsaturated fractured rock. J. Contam. Hydrol., 64, 113–127.], containing two points: (1) questionable phenomenological model for the secondary mineral deposits and (2) inappropriate thermal boundary conditions. In this reply we address primarily the modeling approach by showing results of a sensitivity simulation regarding the effect of an elevated temperature history that approximates the temperature history inferred from fluid inclusions by Wilson et al. (2003) [Wilson, N.S.F., Cline, J.S., Amelin, Y.V., 2003. Origin, timing, and temperature of secondary calcite–silica mineral formation at Yucca Mountain, Nevada. Geochimica et Cosmochimica Acta, 67 (6), 1145–1184.]. Modeled calcite abundances using the time-varying temperature history are similar to the results for the steady-state ambient temperature profile (Xu, T., Sonnenthal, E., Bodvarsson, G., 2003. A reaction-transport model for calcite precipitation and evaluation of infiltration–percolation fluxes in unsaturated fractured rock. J. Contam. Hydrol., 64, 113–127), and are still consistent with the measured abundances at the proposed repository horizon.
