Table.1.

LA-ICP-MS zircon U–Pb dating data from the two tuffs in the Pingdingshan section

Spot232Th (ppm)238U (ppm)232Th/238U207Pb/206Pb207Pb/235U206Pb/238U206Pb/238U (Ma)
CH-3-1139.9267.70.520.051420.001360.290250.007820.040950.000632594
CH-3-2274.1420.90.650.051570.001040.300790.006490.04230.000632674
CH-3-3186.7243.90.770.051460.001280.294140.007570.041460.000642624
CH-3-4152.9166.00.920.051440.001450.29380.008470.041430.000662624
CH-3-5109.7175.50.630.051470.001740.29130.009950.041050.00072594
CH-3-6184.7234.60.790.051420.001860.291760.010580.041160.000742605
CH-3-7263.5481.30.550.051510.001080.301140.006810.04240.000662684
CH-3-8307.5351.80.870.051470.001140.292420.006840.041210.000632604
CH-3-9173.0181.70.950.051470.00150.293680.008740.041380.000662614
CH-3-10364.0328.01.110.051260.002480.284890.013320.040320.00082555
CH-3-11135.2252.50.540.051500.001760.299140.01030.042130.000752665
CH-3-12400.6595.80.670.051560.001120.297550.006910.041860.000662644
CH-3-13180.2317.10.570.051490.001660.295560.00950.041640.000682634
CH-3-14267.3362.70.740.051450.001230.292990.007270.041310.000642614
CH-3-15212.9246.20.860.051280.001970.283050.010750.040030.000712534
CH-3-16148.2248.40.600.051350.001260.284830.007220.040240.000612544
CH-3-17362.1399.00.910.051500.002170.293280.012160.041290.000792615
CH-3-18358.2399.70.900.051520.00120.296870.007250.04180.000642644
CH-3-19313.5396.40.790.051400.001120.288680.006650.040740.000612574
CH-3-20210.4383.00.550.051510.001170.296350.00710.041730.000642644
CH-3-21249.1318.60.780.051510.001240.297350.007480.041880.000652644
CH-3-22301.1545.10.550.051340.001180.297030.007220.041970.000662654
CH-3-23178.8193.60.920.051500.00150.293810.008650.041380.000662614
CH-3-24337.4491.00.690.051510.001220.295960.007250.041670.000632634
CH-3-25169.2320.90.530.051530.002130.295690.011990.041620.000792635
PDS-5-1253.6408.30.620.051570.001320.298440.007910.041980.000672654
PDS-5-2463.0613.70.750.051340.003940.290390.02150.0410.001172597
PDS-5-3289.5424.20.680.051530.001080.300510.00670.04230.000632674
PDS-5-4105.2147.10.720.051450.001830.29690.01050.041850.000692644
PDS-5-5403.8382.61.060.051470.001270.292610.007410.041240.000632614
PDS-5-6209.2291.50.720.051530.001750.296540.010190.041740.000752645
PDS-5-776.6123.40.620.05150.00190.294550.010850.041480.00072624
PDS-5-8260.0367.60.710.051470.001780.294780.010090.041540.00072624
PDS-5-9395.8604.60.650.051510.00150.293230.008790.041290.000722614
PDS-5-10188.3290.60.650.05140.002980.293930.01650.041520.000942626
PDS-5-11350.3385.90.910.051420.002310.293330.012920.041390.000822615
PDS-5-12373.4352.81.060.051490.001690.292020.009720.041130.000732605
PDS-5-13273.9256.91.070.05150.002840.296150.01590.041710.000932636
PDS-5-14126.1222.20.570.051560.002060.296980.011780.041780.000782645
PDS-5-15179.7289.40.620.051440.003990.293910.0220.041430.001132627
PDS-5-16325.2528.20.620.051450.001210.293990.007140.041440.000622624
PDS-5-17282.0318.30.890.051390.001440.287450.008140.040570.000642564
PDS-5-18352.1395.10.890.051510.001710.298930.010030.042090.000732665
PDS-5-19198.0276.50.720.051530.002350.298690.013490.042040.000862655
PDS-5-20161.6225.20.720.051530.003340.294350.018420.041440.000982626
PDS-5-21528.5405.51.300.051440.001790.294810.01010.041580.000712634
PDS-5-22109.9198.00.550.051450.003270.29260.018110.041240.000972616
PDS-5-2355.789.70.620.051420.00270.29450.015190.041540.000812625
PDS-5-24185.1326.00.570.051440.001170.289770.006950.040860.000632584
PDS-5-2582.2125.70.650.051530.002260.296210.012790.04170.000762635
PDS-5-26282.1436.60.650.05140.002240.28830.012280.040690.000782575
PDS-5-27131.8129.51.020.051550.003230.294940.017780.04150.000932626
PDS-5-28245.2305.80.800.051330.001180.286440.006890.040480.000622564
PDS-5-29127.9214.20.600.051460.001540.291570.008870.04110.000682604
PDS-5-30112.4184.20.610.051420.001420.293840.008340.041450.000662624
PDS-5-31358.2329.81.090.051470.001250.292940.007410.041280.000652614