Magnetic anomaly identifications - Nakanishi et al. (1992) Magnetic anomaly identifications between M0 and M29 have been assigned ages in Gee and Kent (2007) (GeeK2007). As GeeK2007 does not provide ages beyond M29, magnetic anomaly identifications pre-M29 (i.e. M30r to M35r) have been assigned ages based on a 'hybrid' version of the Tominaga et al 2008 timescale, where 0.07 Ma has been subtracted from each published age to account for the difference between the last available chron in GeeK2007 (M29r, 157.530 Ma) and Tominaga et al (2008)/Tivey et al. (2006) (M29r, 157.6 Ma). See below for a comparison of the timescales from GeeK2007, Tominaga et al (2008), Tivey et al. (2006), and calculation into the 'hybrid' timescale (second timescale). Author: Nicky Wright, EarthByte, U of Sydney, March 2014. Updated June 2016: Hybrid timescale values are given relative to Tivey et al. (2006) instead of Tominaga et al. (2008). These timescales only differ in their use of decimal places. References: ----------- Nakanishi, M., K. Tamaki, and K. Kobayashi (1992), Magnetic anomaly lineations from Late Jurassic to Early Cretaceous in the west central Pacific Ocean, Geophys. J. Int., 109, 701-719. Tivey, M. A., Sager, W. W., Lee, S. M., & Tominaga, M. (2006). Origin of the Pacific Jurassic quiet zone. Geology, 34(9), 789-792. Tominaga, M., Sager, W. W., Tivey, M. A., & Lee, S. M. (2008). Deep-tow magnetic anomaly study of the Pacific Jurassic Quiet Zone and implications for the geomagnetic polarity reversal timescale and geomagnetic field behavior. Journal of Geophysical Research, 113(B7), B07110. Gee & Kent (2007) Hybrid Tominaga et al. (2008) Tivey et al. (2006) Tominaga et al. (2008), GeeK2007 young old young old young old young old Top (Ma) Base (Ma) Chron Top (Ma) Base (Ma) Chron Top (Ma) Base (Ma) Chron Top (Ma) Base (Ma) Chron 155.800 156.050 CM27r 155.800 156.050 CM27r 155.5 155.7 M27r 155.509 155.684 M27r 156.190 156.510 CM28r 156.190 156.510 CM28r 156 156.2 M28r 156.004 156.164 M28r 156.3 156.5 M28Ar 156.27 156.52 M28Ar 156.6 156.7 M28Br 156.574 156.667 M28Br 156.8 156.9 M28Cr 156.781 156.878 M28Cr 157 157.1 M28Dr 156.963 157.081 M28Dr 156.510 157.270 CM29n 156.510 157.270 CM29n 157.2 157.3 M29n.1r 157.246 157.278 M29n.1r 157.270 157.530 CM29r 157.270 157.530 CM29r 157.3 157.6 M29r 157.349 157.6 M29r 157.582 157.653 M29Ar 157.7 157.7 M29Ar 157.652 157.723 M29Ar 157.785 157.957 M30r 157.9 158 M30r 157.855 158.027 M30r 158.063 158.096 M30Ar 158.1 158.2 M30Ar 158.133 158.166 M30Ar 158.262 158.350 M31n.1r 158.3 158.4 M31n.1r 158.332 158.42 M31n.1r 158.379 158.424 M31n.2r 158.4 158.5 M31n.2r 158.449 158.494 M31n.2r 158.471 158.528 M31r 158.5 158.6 M31r 158.541 158.598 M31r 158.553 158.584 M32n.1r 158.6 158.7 M32n.1r 158.623 158.654 M32n.1r 158.689 158.745 M32n.2r 158.8 158.8 M32n.2r 158.759 158.815 M32n.2r 158.776 158.866 M32r 158.8 158.9 M32r 158.846 158.936 M32r 159.182 159.324 M33r 159.3 159.4 M33r 159.252 159.394 M33r 159.408 159.482 M33Ar 159.5 159.6 M33Ar 159.478 159.552 M33Ar 159.555 159.676 M33Br 159.6 159.7 M33Br 159.625 159.746 M33Br 159.717 159.773 M33Cn.1r 159.8 159.8 M33Cn.1r 159.787 159.843 M33Cn.1r 159.903 160.121 M33Cr 159.9 160.2 M33Cr 159.973 160.191 M33Cr 160.206 160.282 M34n.1r 160.3 160.4 M34n.1r 160.276 160.352 M34n.1r 160.330 160.361 M34n.2r 160.4 160.4 M34n.2r 160.4 160.431 M34n.2r 160.385 160.444 M34n.3r 160.5 160.5 M34n.3r 160.455 160.514 M34n.3r 160.479 160.617 M34Ar 160.5 160.7 M34Ar 160.549 160.687 M34Ar 160.714 160.780 M34Bn.1r 160.8 160.9 M34Bn.1r 160.784 160.85 M34Bn.1r 160.809 160.844 M34Br 160.9 160.9 M34Br 160.879 160.914 M34Br 160.914 161.069 M35r 160.9 161.1 M35r 160.984 161.139 M35r 161.180 161.240 M36n.1r 161.3 161.3 M36n.1r 161.25 161.31 M36n.1r 161.286 161.309 M36Ar 161.4 161.4 M36Ar 161.356 161.379 M36Ar 161.340 161.491 M36Br 161.4 161.6 M36Br 161.41 161.561 M36Br 161.566 161.698 M36Cr 161.6 161.8 M36Cr 161.636 161.768 M36Cr 161.957 162.080 M37n.1r 162 162.2 M37n.1r 162.027 162.15 M37n.1r 162.199 162.302 M37r 162.3 162.4 M37r 162.269 162.372 M37r 162.442 162.494 M38n.1r 162.5 162.6 M38n.1r 162.512 162.564 M38n.1r 162.650 162.693 M38n.2r 162.7 162.8 M38n.2r 162.72 162.763 M38n.2r 162.777 162.896 M38n.3r 162.8 162.9 M38n.3r 162.847 162.966 M38n.3r 163.131 163.204 M38n.4r 163.2 163.3 M38n.4r 163.201 163.274 M38n.4r 163.370 163.440 M38r 163.4 163.5 M38r 163.44 163.51 M38r 163.625 163.745 M39n.1r 163.7 163.8 M39n.1r 163.695 163.815 M39n.1r 163.896 163.966 M39n.2r 163.9 164 M39n.2r 163.966 164.036 M39n.2r 164.100 164.236 M39n.3r 164.2 164.3 M39n.3r 164.17 164.306 M39n.3r 164.391 164.571 M39n.4r 164.5 164.6 M39n.4r 164.461 164.641 M39n.4r 164.700 164.833 M39n.5r 164.8 164.9 M39n.5r 164.77 164.903 M39n.5r 164.934 165.042 M39n.6r 165 165.1 M39n.6r 165.004 165.112 M39n.6r 165.113 165.161 M39n.7r 165.2 165.2 M39n.7r 165.183 165.231 M39n.7r 165.264 165.343 M39r 165.3 165.4 M39r 165.334 165.413 M39r 165.384 165.572 M40n.1r 165.5 165.6 M40n.1r 165.454 165.642 M40n.1r 165.642 165.736 M40n.2r 165.7 165.8 M40n.2r 165.712 165.806 M40n.2r 165.805 166.043 M40n.3r 165.9 166.1 M40n.3r 165.875 166.113 M40n.3r 166.076 166.149 M40r 166.1 166.2 M40r 166.146 166.219 M40r 166.234 166.429 M41n.1r 166.3 166.5 M41n.1r 166.304 166.499 M41n.1r 166.497 166.606 M41n.2r 166.6 166.7 M41n.2r 166.567 166.676 M41n.2r 166.669 166.776 M41n.3r 166.7 166.8 M41n.3r 166.739 166.846 M41n.3r 166.804 166.919 M41r 166.9 166.9 M41r 166.874 166.989 M41r 167.028 167.138 M42n.1r 167.1 167.2 M42n.1r 167.098 167.208 M42n.1r 167.160 167.205 M42n.2r 167.2 167.3 M42n.2r 167.23 167.275 M42n.2r 167.257 167.298 M42n.3r 167.3 167.4 M42n.3r 167.327 167.368 M42n.3r 167.323 167.341 M42n.4r 167.4 167.4 M42n.4r 167.393 167.411 M42n.4r 167.382 167.406 M42n.5r 167.5 167.5 M42n.5r 167.452 167.476 M42n.5r 167.432 167.447 M42n.6r 167.5 167.5 M42n.6r 167.502 167.517 M42n.6r 167.476 167.502 M42n.7r 167.5 167.6 M42n.7r 167.546 167.572 M42n.7r 167.525 167.569 M42n.8r 167.6 167.6 M42n.8r 167.595 167.639 M42n.8r 167.639 167.768 M42n.9r 167.7 167.8 M42n.9r 167.709 167.838 M42n.9r 167.792 167.983 M42n.10r 167.9 168.1 M42n.10r 167.862 168.053 M42n.10r 168.008 168.105 M42r 168.1 168.2 M42r 168.078 168.175 M42r 168.121 168.259 M43n.1r 168.2 168.3 M43n.1r 168.191 168.329 M43n.1r 168.363 168.448 M43n.2r 168.4 168.5 M43n.2r 168.433 168.518 M43n.2r 168.503 168.551 M43n.3r 168.6 168.6 M43n.3r 168.573 168.621 M43n.3r 168.585 168.656 M43n.4r 168.7 168.7 M43n.4r 168.655 168.726 M43n.4r 168.729 168.813 M43r 168.8 168.9 M43r 168.799 168.883 M43r 168.864 168.908 M44n.1r 168.9 168.9 M44n.1r 168.934 168.978 M44n.1r 168.934 168.986 M44n.2r 169 169.1 M44n.2r 169.004 169.056 M44n.2r 169.023 169.166 M44n.3r 169.1 169.2 M44n.3r 169.093 169.236 M44n.3r 169.184 169.242 M44n.4r 169.3 169.3 M44n.4r 169.254 169.312 M44n.4r 169.260 169.337 M44n.5r 169.3 169.4 M44n.5r 169.33 169.407 M44n.5r 169.349 169.421 M44n.6r 169.4 169.5 M44n.6r 169.419 169.491 M44n.6r 169.431 169.474 M44n.7r 169.5 169.5 M44n.7r 169.501 169.544 M44n.7r 169.531 169.558 M44n.8r 169.6 169.6 M44n.8r 169.601 169.628 M44n.8r 169.600 169.638 M44r 169.7 169.7 M44r 169.67 169.708 M44r 169.662 M45r 169.7 M45r 169.732 M45r