A biostratigraphic zonation of the middle and upper siwaliks of the potwar plateau of Northern Pakistan

摘要: Abstract Two biostratigraphic reference sections are designated for the middle and upper Siwalik formations of northern Pakistan. The stratigraphic ranges 41 mammalian taxa established in two correlated to each other standard Magnetic Polarity Time Scale by magnetic-polarity stratigraphy. resulting magnetostratigraphic framework is used define four contiguous interval-zones. proposed interval-zones bounded five important faunal events which identified sections. approximate ages their lower boundaries are: (1) “Hipparion s.l.” Interval-Zone 7.4–9.5 m.y. B.P.; (2) Selenoportax lydekkeri 5.3–7.4 (3) Hexaprotodon sivalensis 5.3-2.9 (4) Elephas planifrons 2.9-1.5 B.P. paleomagnetic evidence indicates that Tatrot Beds, from Pilgrim developed his “Tatrot Faunal Zone”, between 2.5 3.4 B.P., with a preferred maximum age 2.9 Sethi Nagri locality (Y311)—the primary source Pilgrim's “Nagri Zone”— Interval-Zone. suggests an 9 A major event at 9.5 introduced equids, suids, large giraffes Eurasia into Indain subcontinent. second, more diffuse 5.3 several African as well Equus cervids Eurasia.