刀 by F ritz E Steininger, M . P A ubry, W A . B erggren, M . B iolzi, A . M . B orsetti, Julie E . C artlidge, E C ati, R. C orfi eld, R . G elati, S. 1accarino, C . N apoleone, E O tm er, F R6gl, R . R oetzel, S. Spezzqferri, F Tateo, G . Villa, D . Zevenboom The G lobal Stratotype Section and Point (G SSP) for the base of the N eogene The P aleogene-N eogene P eriod-孙stem boundary, L ocal position: 35 rn from the top of the Lem m e- C af osio Section. w hich defines also the O ligocene-M iocene Ep och Sedim entological m arker: A n excellent lithological m arker for the G SSP is provided by a distinct boundary betw een lithologic U nit A -Series boundary is defi ned in the L em m e-C arrosio (the m ore m assive part of the section) and the overlying lithologic section in the village of C arrosio, south of the tow n of U nit B - I (the m ore stratified part of the section) A t the 50 im m ark, G avi and north of Voltaggio 沮lessandria P rovince), there is a horizon w ith yellow ish nodules. T he G SSP is exactly 15 m etres above this lithologic boundary. A layer w ith yellow ish nod- northern Italy. ules lies in lithologic Subunit B 2, exactly one m etre below m etre 35 (Figure 3). A rtificial m arks: The top oft he section (0 m ) corresponds to the top H istorical background and concepts of the R igoroso Form ation. For practical reasons, a m etal stake w as not placed at level 0 but exactly 0.50 m below the top of the form a- T he historical background of the concepts of 'stratigraphic units' of tio n. A steel cable run s fro m th e 0 m m ark to th e b ase o f th e sectio n . L yell （1833) and of M . 1-16m es (1853) (the C hronostratigraphic E ach m etre of the section is m arked by a m etal tag (w ith the m etre U nits of m odem usage) have been based m ainly on tw o observa- num ber). These tags are fixed at the cable and additionally in the for- tions: (1) m ajor or m inor discontinuities (or facies changes) in rock sequences and (2) m ajor or m inor changes in the overall biotic con- I U G S ！C S tent, or w ithin a specific taxonom ic group. M . M im es (1853) defined G S S P the N eogene using both characteristics. In his w ork published in P A L A E O G E N E 1853 (p. 806) H 6m es discussed his 'organic' (paleontologic) reasons N E O G E N E B O U N D A R Y for com bining Lyell's (1833) M iocene and Pliocene into his N eo- A T M E T E R 3 5 gene by referring to the m ollusc fauna: 'die Verschiedenheit der ('of 1 9 9 3 the m ollusc') Fauna der Eoedn- und M iocdn-Epoche' of L yell and m ation. In addition m etre 35 is m arked by a m etal plaque fixed in the in 1864 (p. 510) he pointed out the widespread discontinuities: section w ith the follow ing text. 'Unstreitig haben zw ischen der E ocen- und N eogenzeit gew altige The section has excellent e x p o sure, absence of m ajor structural Schichtstdrungen in Europa stattgefunden'. com plications and apparent absence of unconform ities w ithin the so called 'critical tim e span'. In addition, there is an adequate thickness C oncepts of th e W orking G roup of sedim ents, favorable facies, rather good potential for planktonic The base of the N eogene System and the base of the M iocene Series m ust be situated betw een the C hattian and A quitam an Stages, so that the A quitanian Stage is included in the N eogene System . T he Paleo- gene-N eogene System B oundary coincides w ith the O ligocene-M iocene Series B oundary. T he ideal G SSP candidate for the P aleogene-N eogene System boundary w ould be a tem porally r旧 n a continuous section representing the so called 'critical tim e span'. C. Campagnola This 'critical tim e span' w as determ ined to be represented by the 么 R ic o i biostratigraphic interval betw een planktonic foram iniferal Z ones P21 to M 2 of B erggren et al. (1995). In term s of calcareous nanno- 、， \\'I-. fossil zonation it corresponds to the interval from Zone N P25 t t ，，‘，气 (Sp enolithus ciperoensis Zone) to Z one N N 2 (D iscoaster druggi C am poreg 0 鱿 、、、 Zone) as defined by M artini (197 1) and M artini and M oller (1986). 日erg am o ；(.}arezzanIi M ILA N O N o v a ra 10 产一 M ain features of the proposed G SSP R oc ch e tta 乙anavila R iver N am e: B ase of the N eogene System (base of the M iocene Series, A lessandrra Paleogene-N eogene System boundary and O ligocene- M iocene Series boundary). 口 袱 R ank of the boundary: System (beginning of the N eogene Period) 协 梦飞、 L ocality nam e of the G SSP : L em m e-C arrosio section, Italy 嘛 G eographic position : L ongitude 8'50'11" E ; Latitude: 44'39'32' G E N 半 N . Carta G eologica d'Italia: Foglio G EN OV A N o. 82 (1: 100 000); T av. V O LT A G G IO I N E (I：25 000) (Figure 1) F igure I G eograp hic location of t he L em m e-C arrosio section. Episodes, Vol. 20, no.］ 2 4 and benthic m icrofossil biostratig raphi e s, m agnetostratigraphy, sta- form ed by Perm idic and L igurian tectonic units. T he late E ocene to ble isotope stratigraphy and, eventually cyclostratigraphy. late M iocene succession form s a large hom ocline, gently dipping to T he section is easily accessible by public and priv at e trans- the northw est. T he basin form ed during the late E ocene--early portation and the present ow ner of the property M r. N ando T raverso O ligocene as an extensional basin behind the arc of the W estern has agreed to provide access to colleagues interested in visiting and A lps. It w as affected by the A pennine com pression from late sam pling the section and to conserve the section as an international O ligocene. E vidence ot post late M iocene extensional tectonics are geological point of prim e interest. clearly recorded (Falletti et aL 1994). The facies evolution of the Piedm ont T ertiary B asin is strongly controlled by synsedim entary G eology of the G SSP site tectonic activity and three large-scale facies belts can be recognized. From w est to east: the Langhe-, the V isone-L ernm e- and the Bor- T he are a of the L em m e-C a rro sio section is situ ated w ith in th e P ie d- b era- S taffo ra facie s be lts. T he G S SP sectio n is situated w ithin th e m ont T ertiary B asin, in southern Piedm ont, northw estern Italy (Fig- V isone-L em m e facies belt in the upper part ot the R igoroso Form a- ure 2). T he basin itself is bordered by the arc of the W estern A lps and tion w hich overlies the M olare Form ation (O ligocene fan delta con- by the northw estern end of the N orthern A pennines. Its basem ent is glom erates w ith sandy shallow m arine intercalations yielding m icro- 口 回 姗 皿 黝1 既 塑 黔吕 圈 寨 粼REA 勺 7 藕 厂 V E N E Z IA 干0 一 裹 MILGAENOVA 一” 一 1 P_' _ 一 却 V E R C E L L I o FIR EN ZE 多经． 一 1 ？ 0}} ＿＿关产减沁火 尸 P A V IA O ， 粉篆热 闷 飞 0 、、、 TO RIN O O C A S A LE 瘾童鳌肇缪麟 M O N F E R R A 蒸曰沼豁 1}1笋气CHIERI F,J0 .-4 ". '4%, - 1, -1 7}- 'I} V O G H ER A 0 1 41} 、、 、、 篡 A L ES SA N O AS0TI 群娜尧 巍琴寒橇粼 舜补盆蔑之阅 王口 0 PINERCLO丫 Y v 魏 勺‘ 、 T 类 % 荞 。：。 朴 l茱 燕 薯SALUZZOF O S S A N O 戮.......E.M .I.LIA 魏 嘿 匕 鞭 S v 0 C U N EO N 黝之 ＿0 GE N OVA 一 妇 杂 S A V O N A 0 5 10 k m 1 ． I F igure 2 The geologicf ram e of t he P iedm ont Tertiary B asin. L 6 S Location of the Langluan type section. Upper Eocene to lower Oligocene deposits: 9 Depo-center axis of the Plio-Q uaiernary b a sins . T Location of the Serravallian type section a alluvial to coastal conglom erates, shallow- 10 B u rie d th ru st fro n t o f th e C o llin a d i T o rin o - I Location of the Tortonian type section.