James G. Ogg

A Geologic Time Scale (GTS2004) is presented that integrates currently available stratigraphic and geochronologic information. Key features of the new scale are outlined, how it was constructed, and how it can be further improved. The accompanying International Stratigraphic Chart, issued under auspices of the International Commission on Stratigraphy (ICS), shows the current chronostratigraphic scale and ages with estimates of uncertainty for all stage boundaries. Special reference is made to the Precambrian part of the time scale, which is coming of age in terms of detail, and to the Neogene portion, which has attained an ultra-high-precision absolute-age calibration.

We present an integrated geomagnetic polarity and stratigraphic time scale for the Triassic, Jurassic, and Cretaceous periods of the Mesozoic Era, with age estimates and uncertainty limits for stage boundaries. The time scale uses a suite of 324 radiometric dates, including high‐resolution 40 Ar/ 39 Ar age estimates. This framework involves the observed ties between (1) radiometric dates, biozones, and stage boundaries, and (2) between biozones and magnetic reversals on the seafloor and in sediments. Interpolation techniques include maximum likelihood estimation, smoothing cubic spline fitting, and magnetochronology. The age estimates for the 31 stage boundaries (in mega‐annum) with uncertainty (millions of years) to 2 standard deviations, and the duration of the preceding stages (in parentheses) are Maastrichtian/Danian (Cretaceous/‐Cenozoic) is 65.0±0.1 Ma (6.3 m.y.), Campanian/Maastrichtian is 71.3±0.5 Ma (12.2 m.y.), Santonian/Campanian is 83.5±0.5 Ma (2.3 m.y.), Coniacian/Santonian is 85.8±0.5 Ma (3.2 m.y.), Turonian/Coniacian is 89.0±0.5 Ma (4.5 m.y.), Cenomanian/Turonian is 93.5±0.2 Ma (5.4 m.y.), Albian/Cenomanian is 98.9±0.6 Ma (13.3 m.y.), Aptian/Albian is 112.2±1.1 Ma (8.8 m.y.), Barremian/Aptian is 121.0±1.4 Ma (6.0 m.y.), Hauterivian/Barremian is 127.0±1.6 Ma (5.0 m.y.), Valanginian/Hauterivian is 132.0±1.9 Ma (5.0 m.y.), Berriasian/Valanginian is 137.0±2.2 Ma (7.2 m.y.), Tithonian/Berriasian (Jurassic/Cretaceous) is 144.2±2.6 Ma (6.5 m.y.), Kimmeridgian/Tithonian is 150.7±3.0 Ma (3.4 m.y.), Oxfordian/Kimmeridgian is 154.1±3.2 Ma (5.3 m.y.), Callovian/Oxfordian is 159.4±3.6 Ma (5.0 m.y.), Bathonian/Callovian is 164.4±3.8 Ma (4.8 m.y.), Bajocian/Bathonian is 169.2±4.0 Ma (7.3 m.y.), Aalenian/Bajocian is 176.5±4.0 Ma (3.6 m.y.), Toarcian/Aalenian is 180.1±4.0 Ma (9.5 m.y.), Sinemurian/Pliensbachian is 195.3±3.9 Ma (6.6 m.y.), Hettangian/Sinemurian is 201.9±3.9 Ma (3.8 m.y.), Rhaetian/Hettangian (Triassic/Jurassic) is 205.7±4.0 Ma (3.9 m.y.), Norian/Rhaetian is 209.6±4.1 Ma (11.1 m.y.), Carnian/Norian is 220.7±4.4 Ma (6.7 m.y.), Ladinian/Carnian is 227.4±4.5 Ma (6.9 m.y.), Anisian/Ladinian is 234.3±4.6 Ma (7.4 m.y.), Olenekian/Anisian is 241.7±4.7 Ma (3.1 m.y.), Induan/Olenekian is 244.8±4.8 Ma (3.4 m.y.), Tatarian/Induan (Permian/Triassic) is 248.2±4.8 Ma. The uncertainty in the relative duration of each individual stage is much less than the uncertainties on the ages of the stage boundaries.

This report summarizes the international divisions and ages in the Geologic Time Scale, published
\nin 2012 (GTS2012). Since 2004, when GTS2004 was detailed, major developments have taken place
\nthat directly bear and have considerable impact on the intricate science of geologic time scaling. Precam brian
\nnow has a detailed proposal for chronostratigraphic subdivision instead of an outdated and abstract chronometric
\none. Of 100 chronostratigraphic units in the Phanerozoic 63 now have formal definitions, but stable
\nchronostratigraphy in part of upper Paleozoic, Triassic and Middle Jurassic/Lower Cretaceous is still wanting.
\nDetailed age calibration now exist between radiometric methods and orbital tuning, making 40Ar-39Ar dates
\n0.64% older and more accurate. In general, numeric uncertainty in the time scale, although complex and not
\nentirely amenable to objective analysis, is improved and reduced. Bases of Paleozoic, Mesozoic and Cenozoic
\nare bracketed by analytically precise ages, respectively 541 0.63, 252.16 0.5, and 65.95 0.05 Ma.
\nHigh-resolution, direct age-dates now exist for base-Carboniferous, base-Permian, base-Jurassic, base-Cenomanian
\nand base-Eocene. Relative to GTS2004, 26 of 100 time scale boundaries have changed age, of which
\n14 have changed more than 4 Ma, and 4 (in Middle to Late Triassic) between 6 and 12 Ma. There is much
\nhigher stratigraphic resolution in Late Carboniferous, Jurassic, Cretaceous and Paleogene, and improved integration
\nwith stable isotopes stratigraphy. Cenozoic and Cretaceous have a refined magneto-biochronology.
\nThe spectacular outcrop sections for the Rosello Composite in Sicily, Italy and at Zumaia, Basque Province,
\nSpain encompass the Global Boundary Stratotype Sections and Points for two Pliocene and two Paleocene
\nstages. Since the cycle record indicates, to the best of our knowledge that the stages sediment fill is stratigraphically
\ncomplete, these sections also may fulfill the important role of stage unit stratotypes for three of
\nthese stages, Piacenzian, Zanclean and Danian