The Global Stratotype Section and Point(GSSP)of the base of Langhian Stage(base of the Middle Miocene Subseries)is defined at a level of 17.84 m in the“Lower La Vedova Beach”section in central Italy.This level marks...The Global Stratotype Section and Point(GSSP)of the base of Langhian Stage(base of the Middle Miocene Subseries)is defined at a level of 17.84 m in the“Lower La Vedova Beach”section in central Italy.This level marks the mid-point of the darker marly interval above“Megabed IV”which has been astronomically calibrated to the most prominent~100-kyr eccentricity maximum,with an astronomical age of 15.981 Ma according to La2004 nominal solution,and of 15.978 Ma according to the La2011,in the 405-kyr maximum around 16.0 Ma.The GSSP level in the Lower La Vedova Beach section corresponds closely to the top of Chron C5Cn(at 15.795 m),which is considered the principal event for recognizing the boundary globally.This magnetic reversal with an astronomical age of 16.017 Ma(Turco et al.,2017)(15.97 Ma in Hilgen et al.,2012 ATNTS,2012;15.994 Ma in Raffi et al.,2020 in GTS2020)is preferred to the historical guiding criterion,the Praeorbulina datum,which has been complicated by taxonomic confusion and revision(Turco et al.,2011a),and hence is considered less suitable for recognizing the boundary.The Lower La Vedova Beach section is preferred to the St.Peter’s Pool section(in Malta)as it has an independent astronomical tuning and a better paleomagnetic signal.展开更多
文摘The Global Stratotype Section and Point(GSSP)of the base of Langhian Stage(base of the Middle Miocene Subseries)is defined at a level of 17.84 m in the“Lower La Vedova Beach”section in central Italy.This level marks the mid-point of the darker marly interval above“Megabed IV”which has been astronomically calibrated to the most prominent~100-kyr eccentricity maximum,with an astronomical age of 15.981 Ma according to La2004 nominal solution,and of 15.978 Ma according to the La2011,in the 405-kyr maximum around 16.0 Ma.The GSSP level in the Lower La Vedova Beach section corresponds closely to the top of Chron C5Cn(at 15.795 m),which is considered the principal event for recognizing the boundary globally.This magnetic reversal with an astronomical age of 16.017 Ma(Turco et al.,2017)(15.97 Ma in Hilgen et al.,2012 ATNTS,2012;15.994 Ma in Raffi et al.,2020 in GTS2020)is preferred to the historical guiding criterion,the Praeorbulina datum,which has been complicated by taxonomic confusion and revision(Turco et al.,2011a),and hence is considered less suitable for recognizing the boundary.The Lower La Vedova Beach section is preferred to the St.Peter’s Pool section(in Malta)as it has an independent astronomical tuning and a better paleomagnetic signal.
