R.J. Stewart, B. Hallet, P.K. Zeitler, M.A. Malloy, C. M. Allen and D. Trippett. Nature of sand samples collected downstream of Brahmaputra Canyon

Transcription

1 Data Repository, Stewart, Text and Figure DR 1, page 1 Data Repository "Brahmaputra Sediment Flux Dominated by Highly Localized Rapid Erosion from the Easternmost Himalaya" R.J. Stewart, B. Hallet, P.K. Zeitler, M.A. Malloy, C. M. Allen and D. Trippett Methods, Supplementary Data, and Information Nature of sand samples collected downstream of Brahmaputra Canyon The Pasighat sample is a composite of five samples of the riverbank sediments collected in July 2003, during a major flood that punctuated the 2003 monsoon; this sand must have been suspended high in the water column because it was deposited nearly 10 m above the post-monsoon stage of the river. Even during a normal monsoon period the bed shear stress of the Brahmaputra, which we estimate to be of order 10 3 Pa, is sufficient to move meter-diameter boulders along the riverbed due to the river s steep descent through the canyon and massive discharge; hence all finer material is quickly evacuated from the canyon to the flood plain. Under such conditions all mineral grains finer than 0.5 mm in diameter, including zircons, will be fully suspended and will settle rapidly as flow velocities subside where the Brahmaputra exits the Himalaya and widens into a broad sanded-bedded river. In this context, we assume (1) that our detrital zircons are reliable tracers of the bedrock eroded from the source regions and (2) that in the sand in suspension in the Brahmaputra at Pasighat, the fraction of detrital zircons derived from the Tsangpo canyon equals both that in the bank sediments we sampled and the proportion of sediment derived from the canyon. The quasi steady state attained in this Brahmaputra Canyon region, which is inferred from the long history of rapid erosion that suggests sufficient fluvial incision has occurred for all portions of this landscape to have been affected, simplifies our interpretation because detrital zircons are likely to originate from all parts of the landscape, and their age distribution is not likely to be impacted by erosional transients. In addition, direct field observations and examination of imagery show minimal stored sediment in the canyon (Finnegan et al, 2008) that could complicate interpretation of detrital data derived from region. Zircon concentration in the bedrock of the region is broadly uniform The assumption that the gneisses and granitoids that dominate the bedrock of the eastern Himalaya and southern Tibet have broadly similar zircon concentrations overall is supported by mineral-abundance data showing that zircon concentrations in sands from the Brahmaputra at Pasighat, India, are similar to those from major rivers draining the eastern Himalaya and SE Tibet (Garzanti et al., 2001). Moreover, trace-element data from

2 Data Repository, Stewart, Text and Figure DR 1, page 2 granitoids in southeastern Tibet demonstrate that bedrock zirconium concentrations are broadly uniform in the source area (Booth et al., 2004). Geochemical studies that support estimates of sediment flux The estimate of 210 Mt for the annual suspended sediment load of the Brahmaputra at Pashigat gains support from the more extensive measurements of sediment flux further downstream, as well as from trace-element studies that reflect sediment provenance. Using geochemical data, Singh and France-Lanord (2002) report that the sediment load of the Brahmaputra at Pasighat accounts for 58 ± 23% of the 402 Mt yr -1 average measured downstream between 1955 and 1972 at Pandu-Guwahati (Goswami, 1985); hence, these data are suggestive of an annual sediment load 233 +/- 92 Mt at Pasighat. Model for Determining Sediment Fluxes using U-Pb Data As described in the text, the known distribution of ages in SE Tibet and the eastern Himalaya allow us to estimate the flux of sediment added to the Tsangpo River during its transit through the Namche Barwa-Gyala Peri massif. Work by our project members and others has shown that there are no known sources of young zircons less than 300 Ma in age within this massif, other than volumetrically miniscule leucogranites, pegmatites, and migmatitic sweats that have generally low zircon contents and ages of certainly than 10 Ma and mostly less than 4-5 Ma. In other words, zircons from the metamorphic massif will be Pan African (~500 Ma) and older. In contrast, zircons from the large Tsangpo River watershed upstream of Namche Barwa have a range of ages, including Precambrian values from several groupings, Permo- Triassic ages, Mesozoic ages associated with the Gangdese plutonic arc, and young ages of ~10 to Ma associated with a widespread but volumetrically modest adakitic suite of plutons and volcanics. All these ages are represented in our detrital data from the upstream sample taken from Tsangpo near the village of Pai. Hardly any of our data has an age near 300 Ma, so we take this as a convenient value to use as the criterion for whether a grain is young or old. In our model, any grains added to Tsangpo sediment from the massif will be relatively old and will shift the fraction of old ages in Tsangpo sediment in proportion to the flux of material derived from the massif. Knowing the proportions of old and young ages above and below the massif, we can then calculate the fraction of material that is added during transit through the massif. The calculation for the proportional sediment flux from Namche Barwa is as follows. Downstream at Pasighat, we observe 46 young grains and 104 old ones, for a ratio of Upstream, we observe 90 young and 72 old grains, for a ratio of Under the assumptions of our binary model, we can ask, how many old grains would have to be

3 Data Repository, Stewart, Text and Figure DR 1, page 3 added to the upstream sample in order to achieve the ratio of seen in the downstream sample? This leads to a simple equation: = 90/(72 + x) Solving for x, one obtains as the required number of grains that would have to be added during transit through the gorge for this sample. The upstream sample had 2 grains; adding means that from the perspective of the downstream sample, the fraction of grains added during transit of the massif was 131.5/( ) or This is the origin of our quoted value of ~45% for the derivation from the Namche Barwa massif of sediment in the Tsangpo at Pasighat. Fission-track Dating of Detrital Zircons (Tables DR 1 and 3) For fission-track dating, zircon crystals were mounted in Teflon and etched simultaneously in liquid NaOH/KOH for hours at 2 0C. The etch quality of each sample is excellent; tracks are very well defined. The zircon crystals were irradiated using the external-detector method with neutron monitors of the CN-5 glass standard and zircon from the Fish Canyon Tuff placed at each end of the reactor package. Fluence values were calculated by linear interpolation between the glass standards and track densities were measured at 10 magnification. Data for 296 grains (Table DR1) were analyzed using the BINOMFIT peak-fitting routine of Brandon (1996, 2005a, b; Stewart and Brandon, 2004), which calculates the probability density distribution and searches iteratively for the best-fit set of significant components or "peaks" in the grain-age distribution. The quality of peaks fit is evaluated by the 2 statistic, in turn evaluated by the F-test to determine whether the addition of components or "peaks" results in significant improvement. We must note that this approach uses the age of the youngest peak in a distribution as synonymous with the "minimum age," and should not be confused with the age of the youngest single grain in a population. The youngest peak calculated from BINOMFIT (Brandon, 2005a) is often significantly older and has a smaller error than the age of the youngest grain. U-Pb Dating of Detrital Zircons (Tables DR 2 and 4) Laser ablation ICP-MS analyses of zircon were conducted at the Research School of Earth Sciences, the Australian National University, using standard techniques for analysis and data reduction (Harris et al., 2004). Samples were mounted as whole zircons on adhesive tape. Of relevance to this study, this mounting procedure led to poor viewing conditions that obscured any information about grain color or morphology. This was actually an advantage in eliminating any potential bias in selecting grains for analysis. In two separate sessions, the in-house zircon standard Los Picos returned a weighted mean age of 40.7+/-1.0 Ma (MSWD=27.4, n=11, for 5xx-series grains (Table DR4)) and 42.7+/-0.5 Ma (MSWD=0.79, n=10, for xx-series grains (Table DR4)), as compared to 42.6+/-0.3 Ma (n=2), the lab s running mean age for the annual period beginning July Common Pb corrections were made using the model of Cumming

4 Data Repository, Stewart, Text and Figure DR 1, page 4 and Richards (1975), and U-Pb ages were calculated using standard decay constants of 238 = x yr -1 and 235 = x yr -1 (Steiger and Jaeger, 1977). Due to limitations in the resolution of the LA-ICMPS system related to interferences from Hg, corrections based on 204 Pb were not possible. For many analyses of younger samples, results are highly radiogenic and common-pb corrections remain within the analytical error of the uncorrected analysis. In other cases, especially for young samples, good results for can be obtained using common-pb corrections based on 208 Pb and 207 Pb. To determine what we report in Table DR4 as the selected age for use in calculations and comparisons, we applied a filter to the analytical results depending on the nature of the grain analysis, using such criteria as comparison of U-Pb, Pb-Pb, and Th-Pb ages; absolute U-Pb age; Th/U ratio; and performance of common-pb corrections. These filters for determining the selected age were (see Table DR4 for their application): 1: use the uncertainty-weighted average of the 206 Pb/ 238 U and 207 Pb/ 235 U ages, uncorrected for common Pb (for highly radiogenic samples, most often young ages); 2: use the 207 Pb/ 206 Pb age, uncorrected for common Pb (for old ages); 3: use the 206 Pb/ 238 U age, corrected for common Pb using 207 Pb (for several young ages clearly needing a common-pb correction); 4: use the uncertainty-weighted average of the 206 Pb/ 238 U and 207 Pb/ 235 U ages, corrected for common Pb using 208 Pb (for several young ages); 5: use the 207 Pb/ 206 Pb age, corrected for common Pb using 208 Pb (for a few old ages); 6: use the 206 Pb/ 238 U age, corrected for common Pb using 208 Pb (for just a few young ages). References: Brandon, M.T., 1996, Probability density plots for fission-track age distributions: Radiation Measurements, v. 26, p Brandon, M. T., 2005a, BINOMFIT: A Windows program for estimating fission-track ages for concordant and mixed grain-age distributions, in Reiners, P. W., and Ehlers, T. A., editors, Thermochronology: Reviews in Mineralogy and Geochemistry, p Brandon, M. T., 2005b, Programs for illustrating closure, partial retention and the response of cooling ages to erosion: CLOSURE, AGE2EDOT, and RESPTIME, in Reiners, P. W., and Ehlers, T. A., editors, Thermochronology: Reviews in Mineralogy and Geochemistry, p Cumming, G. L. and Richards, J. R., Ore lead isotope ratios in a continuously changing earth. Earth and Planetary Science Letters, v. 28, p Harris, A. C., Allen, C. M., Bryan, S.E., Campbell, I. H., Holcombe, R. J., and Palin, J. M., ELA-ICP-MS U-Pb zircon geochronology of regional volcanism hosting the Bajo de la Alumbrera Cu-Au deposit: implications of porphyry-related mineralization. Mineralium Deposita, v. 39, p

5 Data Repository, Stewart, Text and Figure DR 1, page 5 Steiger, R. H. and Jaeger, E., Subcommission on geochronology: convention on the use of decay constants in geo- and cosmo-chronology. Earth and Planetary Science Letters, v. 36, p Figure DR1. Location map ( highlighting the syntaxes of the Himalaya, and study area (outlined in yellow) directly north of the key downstream sample site at Pasighat, India on the Brahmaputra River. GPS-based velocity vector shows motion of the India Plate relative to Eurasia.

6 Data Repository, Stewart, Text and Figure DR 1, page 6 TABLE DR1. BEST-FIT PEAKS FOR DETRITAL ZIRCON FT AGES FROM THE BRAHMAPUTRA AND PARLUNG RIVERS, TIBET AND INDIA Minimum-Age Peak Older Peaks Lab Number N t Age 95% Conf. Int. % Age 95% Conf. Int. % Age 95% Conf. Int. % Brahmaputra at Pasighat, India Continued for additional peaks Brahmaputra at Nyang River Parlung River and tributaries Continued for additional peaks Peak ages and 95% confidence interval were estimated using BINOMFIT (Stewart and Brandon, 2004; Brandon, 2005a). N t = total number of dated grains. % = Percent of dated grains in an individual peak. TABLE DR2. LASER-ABLATION ICP/MS AGES OF DETRITAL ZIRCONS FROM THE BRAHMAPUTRA RIVER Sample # #301 #302 Location Brahmaputra R. Tsangpo R. Age (Ma) N t % N t % Notes on possible provenance N. Himalayan leucogranites, 15- Ma Tibetan adakitic suite Gangdese batholith, Tibet Early Gangdese/Transhimalayan batholith in Tibet P-Triassic volc. and granites, ubiquitous in Tibet and Himalaya Pan-African basement, ubiquitous in Tibet and Himalaya Late Proterozoic, common in Namche Barwa massif Mid-Proterozoic units common in Himalaya Old multi-cycle zircons Total Ages are U-Pb ages for concordant grains and those younger than 300 Ma; remaining ages are Pb-Pb ages. Sample localities are shown on Fig. 1. Nt = number of grains in age range. % = Percent of grains in age range.

7 Data Repository, Stewart, Text and Figure DR 1, page 7 Table DR3 Fission Track Data Sheets from BinomFit (3 samples - 21 pages)

8 February :29 BinomFit for Windows ver.1.0 Page 2 Datafile: C:\Documents and Settings\arjs\Desktop\T301.ftz Title: Lab#T301.ftz Trippett Brahmaputra BSAF Tripp_A: RR_ A-2 CN-5 Glass, Stewart 1_29_04 Grain RhoS (Ns) RhoI (Ni) Squares U+/-2s Grain Age (Ma) no. (cm^-2) (cm^-2) Age --95% CI E+05 ( 4) 1.38E+06 ( 33) E+05 ( 14) 4.66E+06 ( 80) E+05 ( 3) 7.54E+05 ( 18) 4.35E+06 ( 83) 2.09E+07 ( 399) E+06 ( 29) 7.33E+06 ( 140) E+06 ( 40) 8.05E+06 ( 192) 4.19E+04 ( 1) 2.51E+05 ( 6) E+05 ( 10) 1.84E+06 ( 44) E+06 ( 20) 4.71E+06 ( 81) 1.36E+06 ( 13) 5.66E+06 ( 54) E+06 ( 14) 5.70E+06 ( 49) E+06 ( 19) 1.68E+07 ( 64) 1.E+06 ( 20) 3.90E+06 ( 67) E+06 ( 15) 5.47E+06 ( 47) E+06 ( 26) 9.08E+06 ( 78) 4.32E+06 ( 66) 1.20E+07 ( 184) E+06 ( 35) 6.57E+06 ( 94) E+06 ( 17) 2.88E+06 ( 44) 2.06E+06 ( 53) 4.97E+06 ( 128) E+06 ( 59) 7.44E+06 ( 142) E+06 ( 14) 3.84E+06 ( 33) 3.E+06 ( 62) 6.86E+06 ( 131) E+06 ( 46) 1.12E+07 ( 96) E+06 ( 36) 3.23E+06 ( 74) 1.38E+06 ( 21) 2.75E+06 ( 42) E+05 ( 22) 1.72E+06 ( 41) E+06 ( 29) 2.72E+06 ( 52) 1.17E+06 ( 28) 2.10E+06 ( 50) E+06 ( 35) 5.33E+06 ( 61) E+06 ( 34) 4.05E+06 ( 58) 3.03E+06 ( 26) 5.12E+06 ( 44) E+06 ( 30) 2.44E+06 ( 49) E+06 ( 29) 3.28E+06 ( 47) 3.49E+06 ( 30) 5.47E+06 ( 47) E+06 ( 30) 5.35E+06 ( 46) E+06 ( 34) 5.45E+06 ( 52) 5.24E+06 ( 20) 7.33E+06 ( 28) E+06 ( 24) 8.64E+06 ( 33) E+06 ( 49) 4.86E+06 ( 65) 3.84E+06 ( 44) 4.98E+06 ( 57) E+06 ( 70) 3.73E+06 ( 89) E+06 ( 64) 5.30E+06 ( 81) 2.88E+06 ( 44) 3.54E+06 ( 54) E+06 ( 32) 4.42E+06 ( 38) E+06 ( 36) 1.05E+07 ( 40) 5.24E+06 ( 45) 5.59E+06 ( 48) E+06 ( 31) 3.72E+06 ( 32) E+06 ( 48) 2.05E+06 ( 49) 5.94E+06 ( 51) 4.66E+06 ( 40) E+06 ( 32) 2.56E+06 ( 22) E+06 ( 37) 1.35E+06 ( 18) POOLED 9.82E+05( 1864) 5.83E+06(11069)

9 February :29 BinomFit for Windows ver.1.0 Page 3 Datafile: C:\Documents and Settings\arjs\Desktop\T301.ftz Title: Lab#T301.ftz Trippett Brahmaputra BSAF Tripp_A: RR_ A-2 CN-5 Glass, Stewart 1_29_04 CHI^2 PROBABILITY (%): 0.0 >>> Beware: possible upward bias in Chi^2 probability due to low counts <<< POOLED AGE W/ 68% CONF. INTERVAL(Ma): 4.2, ( ) 95% CONF. INTERVAL(Ma): ( ) CENTRAL AGE W/ 68% CONF. INTERVAL(Ma): 5.6, ( ) 95% CONF. INTERVAL(Ma): ( ) AGE DISPERSION (%): 115.9

10 February :29 BinomFit for Windows ver.1.0 Page 4 Datafile: C:\Documents and Settings\arjs\Desktop\T301.ftz Title: Lab#T301.ftz Trippett Brahmaputra BSAF Tripp_A: RR_ A-2 CN-5 Glass, Stewart 1_29_04 FIT OPTION: Best-fit peaks using the binomial model of Galbraith and Green INITIAL GUESS FOR MODEL PARAMETERS (number of peaks to fit = 5) Peak #. Peak Age Theta Fraction(%) Count Total range for grain ages: Number of active grains (Num. used for fit): 0.2 to 49.9 Ma 101 Number of removed grains: 0 Degrees of freedom for fit: Average of the SE(Z)'s for the grains: Estimated width of peaks in PD plot in Z units: 0.55 PARAMETERS FOR BEST-FIT PEAKS * Standard error for peak age includes group error * Peak width is for PD plot assuming a kernel factor = 0.60 #. Peak Age(Ma) 68%CI 95%CI W(Z) Frac(%) SE,% Count Log-likelihood for best fit: Chi-squared value for best fit: Reduced chi-squared value: Probability for F test: 2% Condition number for COVAR matrix: Number of iterations:

11 February :29 BinomFit for Windows ver.1.0 Page 5 Datafile: C:\Documents and Settings\arjs\Desktop\T301.ftz Title: Lab#T301.ftz Trippett Brahmaputra BSAF Tripp_A: RR_ A-2 CN-5 Glass, Stewart 1_29_04

12 February :29 BinomFit for Windows ver.1.0 Page 6 Datafile: C:\Documents and Settings\arjs\Desktop\T301.ftz Title: Lab#T301.ftz Trippett Brahmaputra BSAF Tripp_A: RR_ A-2 CN-5 Glass, Stewart 1_29_04

13 February :31 BinomFit for Windows ver.1.0 Page 1 Datafile: C:\Documents and Settings\arjs\Desktop\T302.ftz Title: Lab#T302.ftz Field# NB-1A; Tsangpo River above Pai; RR_ A-6 CN-5 Glass, Stewart 02_07_04 NEW PARAMETERS - ZETA METHOD EFFECTIVE TRACK DENSITY FOR FLUENCE MONITOR (tracks/cm^2): 1.46E+05 RELATIVE ERROR (%): 1.43 EFFECTIVE URANIUM CONTENT OF MONITOR (ppm): ZETA FACTOR AND STANDARD ERROR (yr cm^2): SIZE OF COUNTER SQUARE (cm^2): 9.55E-07 GRAIN AGES IN ORIGINAL ORDER Grain RhoS (Ns) RhoI (Ni) Squares U+/-2s Grain Age (Ma) no. (cm^-2) (cm^-2) Age --95% CI E+06 ( 23) 5.13E+06 ( 98) E+05 ( ) 2.70E+06 ( 103) E+05 ( 9) 2.15E+06 ( 37) 4.19E+06 ( 36) 1.59E+07 ( 137) E+06 ( 18) 4.68E+06 ( 67) E+06 ( 72) 1.59E+07 ( 243) 1.18E+06 ( 18) 3.93E+06 ( 60) E+06 ( 26) 7.33E+06 ( 84) E+06 ( 37) 4.90E+06 ( 117) 3.67E+06 ( 42) 1.10E+07 ( 126) E+06 ( 26) 6.46E+06 ( 74) E+06 ( 42) 7.20E+06 ( 110) 1.11E+06 ( 19) 2.85E+06 ( 49) E+05 ( ) 1.43E+06 ( 41) E+06 ( 24) 6.68E+06 ( 51) 2.68E+06 ( 41) 5.50E+06 ( 84) E+06 ( 95) 9.33E+06 ( 187) E+06 ( 24) 3.67E+06 ( 42) 4.30E+06 ( 41) 6.70E+06 ( 64) E+06 ( 82) 6.14E+06 ( 123) E+05 ( 14) 9.98E+05 ( 20) 1.92E+06 ( 22) 2.71E+06 ( 31) E+06 ( 72) 8.73E+06 ( 100) E+06 ( 65) 3.54E+06 ( 81) 3.67E+06 ( 56) 4.19E+06 ( 64) E+06 ( 49) 2.30E+06 ( 55) E+06 ( 18) 2.10E+06 ( 20) 6.88E+06 ( 46) 7.18E+06 ( 48) E+06 ( 29) 1.75E+06 ( 30) E+06 ( 35) 1.78E+06 ( 34) 7.60E+06 ( 58) 6.81E+06 ( 52) E+06 ( 52) 2.30E+06 ( 44) E+06 ( 63) 3.27E+06 ( 50) 3.01E+06 ( 23) 2.36E+06 ( 18) E+06 ( 32) 1.31E+06 ( ) E+06 ( 42) 2.23E+06 ( 32) 1.89E+06 ( 45) 1.38E+06 ( 33) E+06 ( 47) 1.92E+06 ( 33) E+06 ( 41) 3.67E+06 ( 28) 2.58E+06 ( 37) 1.75E+06 ( ) E+06 ( 48) 2.79E+06 ( 32) E+06 ( 64) 4.98E+06 ( 38) 5.76E+06 ( 44) 3.40E+06 ( 26) E+06 ( 46) 2.01E+06 ( 23) E+06 ( 85) 3.58E+06 ( 41) 2.30E+06 ( 22) 1.05E+06 ( 10) E+06 ( 76) 4.19E+06 ( 32) E+06 ( 81) 1.62E+06 ( 31) 1.63E+06 ( 39) 4.61E+05 ( 11) E+06 ( 58) 1.83E+06 ( 14)

14 February :31 BinomFit for Windows ver.1.0 Page 2 Datafile: C:\Documents and Settings\arjs\Desktop\T302.ftz Title: Lab#T302.ftz Field# NB-1A; Tsangpo River above Pai; RR_ A-6 CN-5 Glass, Stewart 02_07_04 Grain RhoS (Ns) RhoI (Ni) Squares U+/-2s Grain Age (Ma) no. (cm^-2) (cm^-2) Age --95% CI-- POOLED 2.83E+06( 21) 3.96E+06( 2978) CHI^2 PROBABILITY (%): 0.0 POOLED AGE W/ 68% CONF. INTERVAL(Ma): 17.2, ( ) 95% CONF. INTERVAL(Ma): ( ) CENTRAL AGE W/ 68% CONF. INTERVAL(Ma): 19.7, ( ) 95% CONF. INTERVAL(Ma): ( ) AGE DISPERSION (%): 66.6

15 February :31 BinomFit for Windows ver.1.0 Page 3 Datafile: C:\Documents and Settings\arjs\Desktop\T302.ftz Title: Lab#T302.ftz Field# NB-1A; Tsangpo River above Pai; RR_ A-6 CN-5 Glass, Stewart 02_07_04 FIT OPTION: Best-fit peaks using the binomial model of Galbraith and Green INITIAL GUESS FOR MODEL PARAMETERS (number of peaks to fit = 3) Peak #. Peak Age Theta Fraction(%) Count Total range for grain ages: 5.8 to 96.9 Ma Number of active grains (Num. used for fit): 50 Number of removed grains: Degrees of freedom for fit: 0 45 Average of the SE(Z)'s for the grains: 0.24 Estimated width of peaks in PD plot in Z units: 0.28 PARAMETERS FOR BEST-FIT PEAKS * Standard error for peak age includes group error * Peak width is for PD plot assuming a kernel factor = 0.60 #. Peak Age(Ma) 68%CI 95%CI W(Z) Frac(%) SE,% Count Log-likelihood for best fit: Chi-squared value for best fit: Reduced chi-squared value: Probability for F test: % Condition number for COVAR matrix: 3.13 Number of iterations: 13

16 February :31 BinomFit for Windows ver.1.0 Page 4 Datafile: C:\Documents and Settings\arjs\Desktop\T302.ftz Title: Lab#T302.ftz Field# NB-1A; Tsangpo River above Pai; RR_ A-6 CN-5 Glass, Stewart 02_07_04

17 February :31 BinomFit for Windows ver.1.0 Page 5 Datafile: C:\Documents and Settings\arjs\Desktop\T302.ftz Title: Lab#T302.ftz Field# NB-1A; Tsangpo River above Pai; RR_ A-6 CN-5 Glass, Stewart 02_07_04

18 September :27 BinomFit for Windows ver.1.0 Page 1 Datafile: C:\Documents and Settings\arjs\Desktop\303_4_5_8_9_10_combo.ftz Title: Lab#T303combo.ftz NB-3A,8, 13,14,8,17,17A,19 NEW PARAMETERS - ZETA METHOD EFFECTIVE TRACK DENSITY FOR FLUENCE MONITOR (tracks/cm^2): 1.45E+05 RELATIVE ERROR (%): 1.36 EFFECTIVE URANIUM CONTENT OF MONITOR (ppm): ZETA FACTOR AND STANDARD ERROR (yr cm^2): SIZE OF COUNTER SQUARE (cm^2): 9.55E-07 GRAIN AGES IN ORIGINAL ORDER Grain RhoS (Ns) RhoI (Ni) Squares U+/-2s Grain Age (Ma) no. (cm^-2) (cm^-2) Age --95% CI E+05 ( 15) 7.00E+06 ( 7) E+05 ( 5) 5.94E+06 ( 51) E+05 ( 23) 9.05E+06 ( 2) 5.03E+05 ( 12) 4.61E+06 ( 110) E+05 ( 7) 5.59E+06 ( 64) E+06 ( 23) 1.34E+07 ( 205) 1.44E+06 ( 22) 1.26E+07 ( 192) E+06 ( 27) 9.81E+06 ( 234) E+06 ( 21) 1.23E+07 ( 176) 1.05E+06 ( 20) 8.49E+06 ( 2) E+05 ( 13) 4.23E+06 ( 101) E+05 ( 12) 4.49E+06 ( 90) 1.40E+06 ( 12) 1.06E+07 ( 91) E+05 ( 5) 2.15E+06 ( 37) E+05 ( 12) 3.56E+06 ( 85) 7.86E+05 ( 12) 4.58E+06 ( 70) E+06 ( ) 5.91E+06 ( 141) E+06 ( 17) 8.29E+06 ( 95) 5.89E+05 ( 9) 3.34E+06 ( 51) E+05 ( 3) 7.12E+05 ( 17) E+06 ( 24) 5.45E+06 ( 130) 1.05E+06 ( 24) 5.63E+06 ( 129) E+06 ( 33) 9.01E+06 ( 172) E+06 ( ) 1.11E+07 ( 127) 7.33E+05 ( 7) 3.77E+06 ( 36) E+05 ( 13) 4.33E+06 ( 62) E+06 ( 40) 6.53E+06 ( 187) 6.29E+05 ( 9) 2.72E+06 ( 39) E+06 ( ) 4.75E+06 ( 68) E+05 ( 9) 2.65E+06 ( 38) 3.61E+06 ( 31) 1.50E+07 ( 129) E+05 ( 11) 3.93E+06 ( 45) E+05 ( 3.14E+05 ( 6) 2.79E+06 ( 24) 9) 1.26E+06 ( 36) E+06 ( 19) 4.E+06 ( 73) E+06 ( 34) 1.42E+07 ( 122) 2.53E+06 ( 29) 8.90E+06 ( 102) E+05 ( 13) 1.84E+06 ( 44) E+06 ( 38) 7.79E+06 ( 119) 5.11E+06 ( 78) 1.58E+07 ( 241) E+06 ( 59) 1.72E+07 ( 148) E+06 ( 64) 8.05E+06 ( 123) 5.12E+06 ( 44) 9.55E+06 ( 82) E+06 ( 47) 5.43E+06 ( 83) E+06 ( 53) 9.89E+06 ( 85) 5.89E+06 ( 45) 9.43E+06 ( 72) E+06 ( ) 2.51E+06 ( 36) E+06 ( 72) 5.24E+06 ( 100) 5.59E+06 ( 48) 7.68E+06 ( 66) E+06 ( 40) 5.82E+06 ( 50)

19 September :27 BinomFit for Windows ver.1.0 Page 3 Datafile: C:\Documents and Settings\arjs\Desktop\303_4_5_8_9_10_combo.ftz Title: Lab#T303combo.ftz NB-3A,8, 13,14,8,17,17A,19 NEW PARAMETERS - ZETA METHOD EFFECTIVE TRACK DENSITY FOR FLUENCE MONITOR (tracks/cm^2): 1.42E+05 RELATIVE ERROR (%): 1.44 EFFECTIVE URANIUM CONTENT OF MONITOR (ppm): ZETA FACTOR AND STANDARD ERROR (yr cm^2): SIZE OF COUNTER SQUARE (cm^2): 9.55E-07 Grain RhoS (Ns) RhoI (Ni) Squares U+/-2s Grain Age (Ma) no. (cm^-2) (cm^-2) Age --95% CI E+05 ( 8) 2.98E+06 ( 71) E+05 ( 6) 1.83E+06 ( 35) E+06 ( 23) 7.86E+06 ( 120) 5.89E+05 ( 9) 2.95E+06 ( 45) E+06 ( 19) 7.77E+06 ( 89) E+06 ( 23) 1.14E+07 ( 98) 3.49E+05 ( 3) 1.51E+06 ( 13) E+06 ( 23) 1.06E+07 ( 91) E+06 ( 32) 1.44E+07 ( 124) 1.05E+06 ( 18) 3.96E+06 ( 68) E+06 ( 21) 5.52E+06 ( 79) E+06 ( 28) 4.40E+06 ( 105) 1.18E+06 ( 18) 4.32E+06 ( 66) E+05 ( 10) 2.36E+06 ( 36) E+06 ( 18) 4.13E+06 ( 63) 1.05E+06 ( 12) 3.14E+06 ( 36) E+06 ( 26) 8.38E+06 ( 72) E+05 ( 10) 1.41E+06 ( 27) 1.18E+06 ( 18) 3.08E+06 ( 47) E+06 ( 20) 3.01E+06 ( 46) E+06 ( 26) 3.91E+06 ( 56) 9.78E+05 ( 14) 1.96E+06 ( 28) E+06 ( 9) 1.98E+06 ( 17) E+06 ( 34) 4.80E+06 ( 55) 2.10E+06 ( 32) 2.62E+06 ( 40)

20 September :27 BinomFit for Windows ver.1.0 Page 4 Datafile: C:\Documents and Settings\arjs\Desktop\303_4_5_8_9_10_combo.ftz Title: Lab#T303combo.ftz NB-3A,8, 13,14,8,17,17A,19 NEW PARAMETERS - ZETA METHOD EFFECTIVE TRACK DENSITY FOR FLUENCE MONITOR (tracks/cm^2): 1.41E+05 RELATIVE ERROR (%): 1.57 EFFECTIVE URANIUM CONTENT OF MONITOR (ppm): ZETA FACTOR AND STANDARD ERROR (yr cm^2): SIZE OF COUNTER SQUARE (cm^2): 9.55E-07 Grain RhoS (Ns) RhoI (Ni) Squares U+/-2s Grain Age (Ma) no. (cm^-2) (cm^-2) Age --95% CI E+06 ( 21) 5.70E+06 ( 49) E+06 ( 53) 6.42E+06 ( 98) E+06 ( 19) 2.97E+06 ( 34) 1.96E+06 ( 28) 3.49E+06 ( 50) E+06 ( 22) 2.49E+06 ( 38) E+06 ( 38) 4.26E+06 ( 65) 1.05E+06 ( 12) 1.75E+06 ( 20) E+06 ( 28) 3.01E+06 ( 46) E+05 ( 19) 1.52E+06 ( 29) 2.18E+06 ( ) 3.23E+06 ( 37) E+06 ( 26) 2.51E+06 ( 36) E+06 ( 21) 1.90E+06 ( 29) 6.70E+05 ( ) 8.80E+05 ( 21) E+06 ( 29) 1.99E+06 ( 38) E+06 ( 29) 1.89E+06 ( 36) 1.35E+06 ( 18) 1.65E+06 ( 22) E+06 ( 57) 4.39E+06 ( 67) E+06 ( 27) 1.90E+06 ( 29) 2.E+06 ( 33) 2.10E+06 ( 32) E+06 ( 19) 1.48E+06 ( 17) E+06 ( 21) 1.26E+06 ( 18) 1.44E+06 ( 22) 1.18E+06 ( 18) E+06 ( 30) 1.57E+06 ( 24) E+06 ( 28) 1.44E+06 ( 22) 2.33E+06 ( 20) 1.28E+06 ( 11)

21 September :27 BinomFit for Windows ver.1.0 Page 5 Datafile: C:\Documents and Settings\arjs\Desktop\303_4_5_8_9_10_combo.ftz Title: Lab#T303combo.ftz NB-3A,8, 13,14,8,17,17A,19 NEW PARAMETERS - ZETA METHOD EFFECTIVE TRACK DENSITY FOR FLUENCE MONITOR (tracks/cm^2): 1.26E+05 RELATIVE ERROR (%): 1.52 EFFECTIVE URANIUM CONTENT OF MONITOR (ppm): ZETA FACTOR AND STANDARD ERROR (yr cm^2): SIZE OF COUNTER SQUARE (cm^2): 9.55E-07 Grain RhoS (Ns) RhoI (Ni) Squares U+/-2s Grain Age (Ma) no. (cm^-2) (cm^-2) Age --95% CI E+06 ( 37) 4.53E+06 ( 108) E+06 ( 63) 6.87E+06 ( 4) E+05 ( 19) 1.48E+06 ( 34) 1.69E+06 ( 29) 2.50E+06 ( 43) E+06 ( 69) 4.86E+06 ( 102)

22 September :27 BinomFit for Windows ver.1.0 Page 6 Datafile: C:\Documents and Settings\arjs\Desktop\303_4_5_8_9_10_combo.ftz Title: Lab#T303combo.ftz NB-3A,8, 13,14,8,17,17A,19 NEW PARAMETERS - ZETA METHOD EFFECTIVE TRACK DENSITY FOR FLUENCE MONITOR (tracks/cm^2): 1.26E+05 RELATIVE ERROR (%): 1.55 EFFECTIVE URANIUM CONTENT OF MONITOR (ppm): ZETA FACTOR AND STANDARD ERROR (yr cm^2): SIZE OF COUNTER SQUARE (cm^2): 9.55E-07 Grain RhoS (Ns) RhoI (Ni) Squares U+/-2s Grain Age (Ma) no. (cm^-2) (cm^-2) Age --95% CI E+05 ( 14) 2.47E+06 ( 59) E+05 ( 22) 2.93E+06 ( 70) E+06 ( 38) 4.48E+06 ( 107) 1.80E+06 ( 43) 4.82E+06 ( 115) E+06 ( 42) 4.23E+06 ( 101) E+06 ( 58) 5.36E+06 ( 128) 2.64E+06 ( 63) 5.49E+06 ( 131) E+06 ( 50) 3.65E+06 ( 87) E+06 ( 34) 2.26E+06 ( 54) 1.13E+06 ( 27) 1.34E+06 ( 32) E+05 ( 22) 1.05E+06 ( 24) E+06 ( 48) 2.01E+06 ( 48) 2.10E+06 ( 50) 1.93E+06 ( 46) E+07 ( 81) 1.05E+07 ( 60) E+07 ( 97) 9.30E+06 ( 71)

23 September :27 BinomFit for Windows ver.1.0 Page 7 Datafile: C:\Documents and Settings\arjs\Desktop\303_4_5_8_9_10_combo.ftz Title: Lab#T303combo.ftz NB-3A,8, 13,14,8,17,17A,19 NEW PARAMETERS - ZETA METHOD EFFECTIVE TRACK DENSITY FOR FLUENCE MONITOR (tracks/cm^2): 1.26E+05 RELATIVE ERROR (%): 1.60 EFFECTIVE URANIUM CONTENT OF MONITOR (ppm): ZETA FACTOR AND STANDARD ERROR (yr cm^2): SIZE OF COUNTER SQUARE (cm^2): 9.55E-07 Grain RhoS (Ns) RhoI (Ni) Squares U+/-2s Grain Age (Ma) no. (cm^-2) (cm^-2) Age --95% CI E+06 ( 29) 2.68E+06 ( 64) E+06 ( 29) 3.54E+06 ( 54) E+06 ( 43) 2.81E+06 ( 67) 2.55E+06 ( 39) 3.86E+06 ( 59) E+06 ( 36) 3.08E+06 ( 47) E+06 ( 36) 2.68E+06 ( 41) 1.70E+06 ( 26) 1.77E+06 ( 27) E+06 ( 47) 2.49E+06 ( 38) E+06 ( 28) 2.33E+06 ( 20) 2.36E+06 ( 36) 1.18E+06 ( 18) E+06 ( 47) 2.44E+06 ( 21) E+06 ( 26) 6.55E+05 ( 10) 2.E+06 ( 33) 7.86E+05 ( 12) E+06 ( 44) 9.82E+05 ( 15) E+06 ( 45) 9.82E+05 ( 15) 4.06E+06 ( 62) 1.31E+06 ( 20) E+06 ( 63) 1.24E+06 ( 19)

24 September :27 BinomFit for Windows ver.1.0 Page 8 Datafile: C:\Documents and Settings\arjs\Desktop\303_4_5_8_9_10_combo.ftz Title: Lab#T303combo.ftz NB-3A,8, 13,14,8,17,17A,19 NEW PARAMETERS - ZETA METHOD EFFECTIVE TRACK DENSITY FOR FLUENCE MONITOR (tracks/cm^2): 1.26E+05 RELATIVE ERROR (%): 1.55 EFFECTIVE URANIUM CONTENT OF MONITOR (ppm): ZETA FACTOR AND STANDARD ERROR (yr cm^2): SIZE OF COUNTER SQUARE (cm^2): 9.55E-07 Grain RhoS (Ns) RhoI (Ni) Squares U+/-2s Grain Age (Ma) no. (cm^-2) (cm^-2) Age --95% CI E+05 ( 18) 2.10E+06 ( 50) E+06 ( 26) 1.84E+06 ( 44) E+05 ( 20) 1.44E+06 ( 33) 1.59E+06 ( 38) 2.47E+06 ( 59) E+06 ( 40) 7.22E+06 ( 62) E+06 ( 46) 4.19E+06 ( 64) 2.49E+06 ( 38) 3.40E+06 ( 52) E+06 ( 36) 2.30E+06 ( 33) POOLED 1.78E+06( 4218) 4.44E+06(10506) CHI^2 PROBABILITY (%): 0.0 >>> Beware: possible upward bias in Chi^2 probability due to low counts <<< POOLED AGE W/ 68% CONF. INTERVAL(Ma): 9.6, ( ) 95% CONF. INTERVAL(Ma): ( ) CENTRAL AGE W/ 68% CONF. INTERVAL(Ma): 11.0, ( ) 95% CONF. INTERVAL(Ma): ( ) AGE DISPERSION (%): 69.0

25 September :27 BinomFit for Windows ver.1.0 Page 9 Datafile: C:\Documents and Settings\arjs\Desktop\303_4_5_8_9_10_combo.ftz Title: Lab#T303combo.ftz NB-3A,8, 13,14,8,17,17A,19 FIT OPTION: Best-fit peaks using the binomial model of Galbraith and Green INITIAL GUESS FOR MODEL PARAMETERS (number of peaks to fit = 5) Peak #. Peak Age Theta Fraction(%) Count Total range for grain ages: Number of active grains (Num. used for fit): 2.2 to 67.7 Ma 145 Number of removed grains: 0 Degrees of freedom for fit: Average of the SE(Z)'s for the grains: Estimated width of peaks in PD plot in Z units: 0.31 PARAMETERS FOR BEST-FIT PEAKS * Standard error for peak age includes group error * Peak width is for PD plot assuming a kernel factor = 0.60 #. Peak Age(Ma) 68%CI 95%CI W(Z) Frac(%) SE,% Count Log-likelihood for best fit: Chi-squared value for best fit: Reduced chi-squared value: Probability for F test: 2% Condition number for COVAR matrix: Number of iterations:

26 September :27 BinomFit for Windows ver.1.0 Page 10 Datafile: C:\Documents and Settings\arjs\Desktop\303_4_5_8_9_10_combo.ftz Title: Lab#T303combo.ftz NB-3A,8, 13,14,8,17,17A,19

27 September :27 BinomFit for Windows ver.1.0 Page 11 Datafile: C:\Documents and Settings\arjs\Desktop\303_4_5_8_9_10_combo.ftz Title: Lab#T303combo.ftz NB-3A,8, 13,14,8,17,17A,19

28 Table DR4A. LA-ICPMS U-Pb Data, Tsangpo-River Zircons Sample 301 ("Downstream" at Pasighat) Table DR 4A. LA-ICPMS U-Pb Data, Tsangpo-River Zircons Sample 301 ("Downstream" at Pasighat) Grain Selected Age (Ma) U Th/U ƒ-207 ƒ-208 Age Ages (Uncorrected for Common Pb) (Ma) Ages (Corrected for Common Pb Using 208-Pb) (Ma) Ages (207-Correct (Ma) 6/38 ±1 (ppm) Filter age ±1 7/35 age ±1 7/6 age ±1 6/38 age ±1 7/35 age ±1 7/6 age ±1 6/38 age sng % -0.08% sng % 1.06% sng % -0.30% sng % 0.55% sng % -1.24% sng % -0.07% sng % -0.12% sng % -0.60% sng % -0.31% sng % -0.57% sng % 0.51% sng % -1.62% sng % 35.87% sng % 0.44% sng % 1.40% sng % -2.38% sng-61(2) % -0.32% sng % 0.87% sng % 0.67% sng % -1.72% sng % 0.53% sng % 0.08% sng % 0.09% sng % 0.96% sng % 0.01% sng % -0.95% sng % 0.10% sng % -1.32% sng % 2.45% sng % -1.47% sng % 0.29% sng % 2.63% sng % -0.52% sng % 0.30% sng % 0.06% sng % -0.67% sng % 0.19% sng % 0.31% sng % -0.42% sng % 0.74%

29 Table DR4A. LA-ICPMS U-Pb Data, Tsangpo-River Zircons Sample 301 ("Downstream" at Pasighat) Table DR 4A. LA-ICPMS U-Pb Data, Tsangpo-River Zircons Sample 301 ("Downstream" at Pasighat) Grain Selected Age (Ma) U Th/U ƒ-207 ƒ-208 Age Ages (Uncorrected for Common Pb) (Ma) Ages (Corrected for Common Pb Using 208-Pb) (Ma) Ages (207-Correct (Ma) 6/38 ±1 (ppm) Filter age ±1 7/35 age ±1 7/6 age ±1 6/38 age ±1 7/35 age ±1 7/6 age ±1 6/38 age sng-054-a % 0.02% sng % -0.10% sng % 0.01% sng % 0.13% sng-522-a % 0.07% sng % 0.73% sng % 5.23% sng % 0.52% sng % 0.61% sng % 0.05% sng % -0.42% sng-052-b % -0.15% sng-087-b % 0.00% sng % -0.42% sng % -4.26% sng % 1.18% sng % 0.67% sng % 1.69% sng % 0.56% sng % 0.84% sng % 0.02% sng % -0.80% sng % -0.65% sng % 0.20% sng % 0.11% sng % 0.41% sng % -3.05% sng % -0.06% sng % 0.% sng % -0.54% sng % 1.44% sng-506-a % 1.30% sng % -2.23% sng % -0.10% sng % 0.00% sng-003a % 13.03% sng % 1.29% sng % 0.04% sng % -1.08% sng % 2.52%

30 Table DR4A. LA-ICPMS U-Pb Data, Tsangpo-River Zircons Sample 301 ("Downstream" at Pasighat) Table DR 4A. LA-ICPMS U-Pb Data, Tsangpo-River Zircons Sample 301 ("Downstream" at Pasighat) Grain Selected Age (Ma) U Th/U ƒ-207 ƒ-208 Age Ages (Uncorrected for Common Pb) (Ma) Ages (Corrected for Common Pb Using 208-Pb) (Ma) Ages (207-Correct (Ma) 6/38 ±1 (ppm) Filter age ±1 7/35 age ±1 7/6 age ±1 6/38 age ±1 7/35 age ±1 7/6 age ±1 6/38 age sng % 0.00% sng % 0.33% sng % -0.06% sng % 0.13% sng % 4.11% sng % -0.27% sng % 1.88% sng % 0.09% sng % 0.29% sng % -0.22% sng % -0.% sng % 0.09% sng % 0.73% sng % 0.76% sng % -0.% sng % -1.85% sng % 0.96% sng % -0.34% sng % -1.29% sng % -0.60% sng % -0.57% sng % -0.42% sng % 0.49% sng % 0.37% sng % -0.17% sng % -4.00% sng % -1.83% sng % 0.03% sng % -3.33% sng % -2.21% sng % 0.28% sng % 1.30% sng % -0.32% sng % -0.05% sng % -0.28% sng % -0.52% sng % 0.02% sng % 0.04% sng % -0.65% sng % -0.23%