Late Cretaceous marine transgressions in Ecuador and northern Peru: a refined stratigraphic framework

Late Cretaceous marine transgressions in Ecuador and northern northern Peru: a refined refined stratigrap stratigraphic hic framew framework. ork. Etienne Jaillard, Peter Bengtson, Annie V. Dhondt

To cite this version: Etienne Jaillard, Peter Peter Bengtson, Annie V. Dhondt. Late Cretaceous marine transgressions transgressions in Ecuador Ecuador and northern northern Peru: Peru: a refined refined stratigraph stratigraphic ic framework. framework... Journal Journal of South South American American Earth Sciences, Elsevier, 2005, 19, pp.307-323. <hal-00101736 >

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Late Cretaceous marine transgressions in Ecuador and northern Peru: a refined stratigraphic framework  Etienne Jaillarda, Peter Bengtson b and Annie V. Dhondt c a IRD-LGCA, Université de Grenoble, Maison des Géosciences, BP 53, F-3!"# Grenoble cede$,  France% or IRD-LM&G, 'bservatoire Midi-P(rénées, #" aven)e *do)rd Belin, F-3#"!! &o)lo)se, France%  *-+ail *tienne.aillard/)01-2renoble1r  bGeolo2isc-Pal4ontolo2isces Instit)t, I+ e)enei+er Feld 63", D-78#6! 9eidelber2, Ger+an(%  *-+ail ben2tson/)ni-dde c De:art+ent o1 Palaeontolo2(, ;onin<li0< Bel2isc Instit))t voor at))r=etensca::en, >a)tierstraat >a)tierstraat 68, B-#!!! Br)ssels, Bel2i)+%  *-+ail AnnieDondt/nat)ralsciencesbe

Received 9 January 200! revised revised  August 200"! acce#ted $$$

Abstract

%tudy o& a''onites and bivalves along selected sections on the Andean 'argin o& northern Peru and Ecuador has 'ade it #ossible to recogni(e correlatable 'arine transgressions and to #ro#ose a re&ined stratigra#hic &ra'e)or* &or the +##er retaceous o& the region. %i- 'a-i'u' &looding events are recogni(ed latest /uronianearly oniacian 1'aor event3, late oniacianearly %antonian, late %antonianearly %antonianearly a'#anian, 'id a'#anianearly late a'#anian 1'aor event3, early 4aastrichtian 1'aor event3, and ter'inal early 4aastrichtian. 4ost o& these events can  be correlated )ith global global eustatic sea5level sea5level rises, but their relative 'ani&estations indicate that the Andean 'argin )as already being de&or'ed by the late retaceous “Peruvian” tectonic events. /he onset o& &ine5grained clastic sedi'entation in the 6riente and East5Peruvian basins in the 'id /uronianearliest oniacian is ta*en as the &irst event o& the “Peruvian” #hase. /he a'#anian regional transgression in the Peruvian5Ecuadorian Peruvian5Ecuadorian &orearc (ones concealed the “Peruvian” de&or'ational event. /he latter caused a #alaeogeogra#hic #alaeogeogra#hic u#heaval, indicated by the subse7uent develo#'ent o& a 88E5trending &orearc basin, )hich e-tended &ro' Paita in north)estern Peru to northern Ecuador. n the &orearc (ones only short5lived transgressions are recorded in the late a'#anian and early 4aastrichtian as a result o& nearly continuous tectonic activity. /his cul'inated )ith a signi&icant tectonic event in the late 4aastrichtian, causing a )ides#read hiatus.  ;e(=ords :ate

Ecuador! Peru

retaceous! stratigra#hy! a''onites! inocera'ids! transgressions!

1. Introduction

/he active 'argin o& )estern %outh A'erica is 'ar*ed by the develo#'ent o& the e-tensive retaceous Andean Basin, )hich enco'#assed large #arts o& Ecuador, Peru and central Bolivia. /he late /uronian4aastrichtian /uronian4aastrichtian interval is a crucial #eriod, )hich sa) the onset o& co'#ressional de&or'ation and u#li&t o& the Andean 'argin &ollo)ed & ollo)ed  by a 'arine regression regression in the Andean Andean Basin 1e.g. %tein'ann, %tein'ann, ;929! Jaillard Jaillard et al., 20003. During Albiana'#anian ti'es, the de#ocenter o& the Andean Basin )as located in northern Peru. n this area, the +##er retaceous sedi'entary successions successions are richly &ossili&erous and the ter'inal retaceous regional regression occurred later than

2 in other Andean areas. onse7uently, the :ate retaceous 'arine transgressions in this area are )ell recorded in the sedi'entary succession. /ectonic activity on the Andean 'argin began in the :ate retaceous, and caused increasing u#li&t and erosion, #articularly in the &orearc and arc (ones and in the )estern bac*arc areas 1#resent5day coast and the )estern ordillera3. /his 'ay have obscured the global, synchronous eustatic signal, 'a*ing reliable chronostratigra#hic correlations across the Andes di&&icult. Although 'arine transgressions can be caused  by tectonic subsidence, tectonic events, ho)ever, do not erase the eustatic signal! the sedi'entary &ill o& the tectonically controlled Andean basins record these eustatic transgressions. n order to veri&y the eustatic origin o& the transgressions, )e discuss their geogra#hical e-tent and co'#are the' )ith coeval transgressions recorded in other regions in and around %outh A'erica. Although the stratigra#hy o& these areas has been studied since early in the last century, no detailed biostratigra#hic )or* has been carried out in the #ast &i&ty years. <e here revie) the #alaeontological data and stratigra#hic assign'ents, in the light o& current #alaeontological and biostratigra#hic *no)ledge. =o)ever, the nature, evolution and age range o& the %outh A'erican 'acro&aunas re'ain #oorly *no)n, 'a*ing accurate deter'inations and datings di&&icult. 8evertheless, #recise dating o& the 'a-i'u' &looding events o& 'arine transgressions, considered as ti'e5lines, )ill 'a*e it #ossible to correlate the &orearc and bac*arc de#osits and hence the sedi'entary and tectonic events across the Andean 'argin and, ulti'ately, to clari&y the early evolution o& the Andean 'argin. >or these reasons, )e undertoo* a detailed stratigra#hic study o& the +##er retaceous o& northern Peru and Ecuador. =ere )e #resent our results &or the oniacian4aastrichtian succession based on study o& 'acro&ossils 1'ainly a''onites and inocera'id bivalves3 collected &ro' selected sections in eastern and southern Ecuador and northern Peru 1>ig. ;3. 8u'bers in brac*ets a&ter s#ecies na'es are &ield codes denoting locality or hori(on. %#ecies 'entioned in the literature )ithout descri#tion or illustration or lac*ing #recise locality data are not discussed in detail. >or the /uronianoniacian and a'#anian4aastrichtian stage boundaries )e use the de&initions based on the #ro#osed ?%%P 1?lobal boundary %tratoty#e %ection and Point3 &or the base o& the oniacian 1@au&&'an et al., ;993 and the rati&ied ?%%P &or the base o& the 4aastrichtian 16din and :a'aurelle, 200;3. /he oniacian  %antonian and %antoniana'#anian stage boundaries have not yet been &or'ally de&ined. 2. Geoogica setting

During the retaceous the Andean 'argin )as sub'itted to continuous 85 to 8E5 )ard directed subduction. /he Peruvian 'argin co'#rised &ro' )est to east a narro) &orearc (one! a still #oorly *no)n, 'ainly subaerial arc (one! and a )ide bac*arc (one. /he bac*arc (one co'#rised a subsiding basin in the )est 1<est5Peruvian /rough, >ig. ;3, )hich )as se#arated &ro' a 'oderately subsiding basin in the east 1East5Peruvian Basin3 by a #ositive area 14araCn ?eanticline, Benavides5ceres, ;9! <ilson, ;93. n Ecuador, the eastern bac*arc (one, re#resented by the 6riente Basin, is se#arated &ro' the signi&icantly de&or'ed )estern areas by the #resent5day Eastern ordillera. /here, intra5oceanic subduction is assu'ed to have occurred &arther <est, eventually causing accretion o& oceanic terranes in the :ate retaceousPalaeogene 1Reynaud et al., ;999! @err et al., 20023. Recent geological studies and 'a##ing o& the &orearc (ones have sho)n that the retaceous sedi'entary roc*s belong to t)o distinct &orearc basins o& early :ate retaceous and latest retaceous age, res#ectively 1Jaillard et al., ;99! ;99F! ;9993. /he de#osits contained in these basins are se#arated by a regional uncon&or'ity 1Jaillard et al., ;9993, related to the GPeruvianH tectonic #hase 1%tein'ann, ;9293. 4ost

 o& the data #resented here concern the :a /ortuga and :a 4esa sections, south o& Paita in north)estern Peru, and the “elica5:ancones basin ”. /he latter co'#rises an eastern arc succession 1rIo Playas section3 and a )estern succession that constitutes the cover o& the A'ota#e/ahuin 4assi& 1Puyangoa(aderos section3 1>ig. ;, c&. >ig. "3. n addition, biostratigra#hically signi&icant 'acro&ossils have been collected &ro' nu'erous outcro#s in north)estern Peru and southern Ecuador.

!ig. 1: ?eneral location 'a#.

/he <est5Peruvian /rough received a thic* #ile o& 'ainly 'arine sedi'ents  bet)een Valanginian and a'#anian ti'es 1Benavides5ceres, ;9! Robert, 20023. t co'#rises a strongly subsided (one centered around =uara(, and a 'oderately subsided  #lat&or' north o& aa'arca 1>ig. ;3. /he trough does not e-tend north)ard into Ecuador. /he sections studied here are located at aa'arca and Pongo de Rente'a, the latter situated on the boundary bet)een the <est5Peruvian /rough and the East5 Peruvian Basin 1the Bagua basin o& 4ourier et al., ;9FF3. /he eastern basins o& Ecuador 16riente Basin3 and Peru 14araCn Basin, >ig. ;3 are characteri(ed by 'arine de#osits o& Albian%antonian age, &ollo)ed by a do'inantly non5'arine succession o& 4aastrichtianEocene age 1/scho##, ;9! 4athalone and 4ontoya, ;99! Jaillard, ;99a3. Data &ro' these areas are based on the rIo 4isahuallI 1Ecuador3 and Pongo de Rente'a sections 1Peru3, &ro' scattered outcro#s, and &ro' #ublished and un#ublished data related to #etroleu' e-#loration. /he &orearc basins are characteri(ed by active tectonics, by subsiding and 'obile

" troughs and by o#en 'arine environ'ents )hich continued locally until the end o& the Eocene. By contrast, the eastern basins are 'ar*ed by stable tectonic conditions, lo) subsidence rates, shallo) restricted environ'ents and by short5lived 1although )ides#read3 'arine transgressions during the %antonian4aastrichtian. /he <est5 Peruvian /rough dis#lays inter'ediate characteristics. /here&ore, biostratigra#hic correlation o& the &ossili&erous o#en5'arine asse'blages o& the &orearc (ones )ith the restricted, 'ainly 'icro#alaeontological asse'blages o& the eastern basins #resents  #roble's. ". Post#$uronian transgressions in the backarc basins

/he /uronian o& the Andean Basin )as characteri(ed by sedi'entation on a )ide carbonate #lat&or'. /his de#ositional regi'e )as interru#ted in the late /uronianearly oniacian by a 'aor transgression )hich 'ar*ed the onset o& e-tensive &ine5grained terrigenous clastic sedi'entation 1Benavides5ceres, ;9! <ilson, ;9! Jaillard, ;99"3. 3# Latest &)ronian?earl( Coniacian +a$i+)+ 1loodin2 event  3## Per)

>ro' the 'arls o& the honta >or'ation o& the northern #art o& the East5Peruvian Basin 14araCn Basin, >ig. ;3, @u''el 1;9"F3, Rosen()eig 1;93 and Duclo( and Rivera 1;93 re#orted nu'erous s#eci'ens o& the a''onite genus &issotia, so'e  Lenticeras, B)ciceras, Barroisiceras, and scarce Coilo:oceras, *)lo:oceras and >ascoceras. /hey considered this &auna to be o& /uronian1K3oniacian age. Legarra 1;9"3 'entioned a &auna characteri(ed by  Barroisiceras s#. 1a'ong )hich  B. c&. aber1ellneri 1von =auer, ;F33 and  B)ciceras bilobat)+ =yatt, ;F, associated )ith 9a)ericeras s#., Peroniceras c&. +o)reti de ?rossouvre, ;F9",  Lenticeras andii 1?abb, ;F3, des'oceratids and tissotiids. n the northern #art o& the <est5Peruvian /rough 1aa'arca area3, Benavides5 ceres 1;93 de&ined the  B)ciceras bilobat)+ Lone containing s#ecies o&  Barroisiceras, @ol2erites, Forresteria, &issotia, 9eterotissotia and B)ciceras, traditionally a ty#ical lo)er oniacian asse'blage 1Bengtson, ;9FF3. =o)ever, the recently #ro#osed ?lobal boundary %tratoty#e %ection and Point 1?%%P3 &or the base o& the oniacian 1base o& bed 4@ " in the %al(gitter5%alder Muarry in :o)er %a-ony, ?er'any! @au&&'an et al., ;993 lies stratigra#hically higher than the #reviously acce#ted stage boundary based on a''onites. /he  B)ciceras bilobat)+ Lone, at least in #art, should there&ore no) be re&erred to the u##er /uronian. E-tensive collections along the Pongo de Rente'a section, on the boundary  bet)een the <est5 and East5Peruvian basins 1>igs ; and 23, have yielded the &ollo)ing a''onites and bivalves in sit), listed in stratigra#hical order 5 &ro' /uronian 'arls and li'estones oilo#oceratidae s#. 1R.93,  M(tiloides labiat)s 1von %chlothei', ;F;3 1R.93,  ;a+er)nocerasK s#. 1R.03! 5 &ro' oniacian shales Paratissotia s#. 1R.3, &e$anites c&. vanoe:eni @linger N @ennedy, ;9F0 1R.3,  9eterotissotia uv. 1R.;"3, Lenticeras s#. 1R.;"3,  MetatissotiaK s#. 1R.;2, R.;2;, R.;2"3,  Lenticeras andii 1R.;23 and /issotiidae indet. 1R.;2F, R.;0, R.;;3. /he bivalves  Plat(cera+)s c&. c(cloides 1<egner, ;903 1R.;23, Plat(cera+)s s#. 19.R.;3, Cordicera+)s e-. gr. +)elleri 1Petraschec*, ;90"3 1R.;3 in the lo)er #art o& the succession and Plat(cera+)s c(cloides 1R.;2"3 in the u##er #art suggest a oniacian%antonian age 1>ig. 23. n addition to these s#eci'ens, )e have studied 'aterial collected by geologists o& PetrCleos del PerO 5 PetroPerO %.A. and 6ccidental Petroleu' o'#any 16-y3 &ro' the Pongo de Rente'a section. /his 'aterial has been calibrated )ith our data, although 'any o& the PetroPerO and 6-y s#eci'ens a##ear to be derived &ro' higher levels as a

 result o& gravitational andor river trans#ort. /he late /uronianearly oniacian transgression is associated )ith the onset o& terrigenous clastic de#osition.

!ig. 2: %tratigra#hic section at Pongo de Rente'a 1northern Peru3 )ith ranges and

occurrences o& the 'ain diagnostic ta-a. 3#6 *c)ador 

>ro' the 6riente Basin 1>ig. 3, /scho## 1;93 and =obbs 1;93 re#orted  Peroniceras s#. 1lo)er or 'iddle oniacian3. n the northern #art o& the basin 1RIo Muios3, 4onciardini et al. 1;9F"3 ascribed a ;05'5thic* succession to the oniacian on the basis o& the &ora'ini&ers  Arceo2lobi2erina a&&. cretacea 1dQ6rbigny, ;F"03,  Dicarinella :ri+itiva 1Dalbie(, ;93 and  Mar2inotr)ncana e- gr. renian2)sticarinata 1?andol&i, ;9"23. A latest /uronian 1in current ter's! see above3 'arine transgression has also  been identi&ied in the rIo 4isahuallI section 1Jaillard, ;99a, >ig. 3. At the to# o& the u##er /uronian 452 li'estones, transgressive calcareous beds yielded the inocera'id

  M(tiloides s#. and the a''onite  Barroisiceras s#. 19.3. >ro' a level ;0

' above these occurrences, in 'arine shales re#resenting the 'a-i'u' &looding event, )e collected M(tiloides s#. 19".9, 9".9a3,  Arceo2lobi2erina a&&. cretacea, Dicarinella  :ri+itiva and 9edber2ella :lanis:ira 1/a##an, ;9"03 and the nanno&ossil  Martasterites 1)rcat)s 1De&landre in De&landre et >ert, ;9"3 1Jaillard, ;99a3. /he co5 occurrence o& M(tiloides s#. and Barroisiceras in this section indicates a latest /uronian age &or the transgression. /his dating is consistent )ith the occurrence o&  Dicarinella egr. a2ni-concavata 1Brot(en, ;9"3, Mar2inotr)ncana si2ali 1Reichel, ;9"93 and iteinella s##. in the transgressive beds discon&or'ably overlying the 452 li'estones in the 4irador section 1Jaillard, ;99a3.

!ig. ": %ection and electric logs &or the 6riente Basin 1Ecuador3, )ith stratigra#hic

occurrences o& the 'ain diagnostic ta-a.

>arther north 1rIo Muios3, &ro' shales a##ro-i'ately 20 ' above the 452 :i'estones, P. Baby 1RD3 collected a loose i'#ression o& a #eroniceratine a''onite 19.;Eb3, suggesting an early or 'id oniacian age. 36 Late Coniacian?earl( @antonian +a$i+)+ 1loodin2 event  36# Per)

n the East5Peruvian Basin o& northern Peru, @u''el 1;9"F3, Rosen()eig 1;93 and Duclo( and Rivera 1;93 &ound no evidence o& %antonian. Legarra 1;9"3 'entioned the a''onite &e$anites s#. and nu'erous s#eci'ens o& &issotia 1& . c&.  sin2e=aldi @nechtel, ;9", & . c&. rosceni @nechtel, ;9", &issotia nov. s#.3 collected above the Barroisiceras   B)ciceras asse'blage, indicating 'iddle or u##er oniacian. n the northern #art o& the <est5Peruvian /rough 1aa'arca area3, Benavides5 ceres 1;93 de&ined the  Lenticeras baltai Lone and described  Bostr(cocerasK s#.,  Des+o:(llites 2a)dana 1>orbes, ;F"3, &e$anites o)rci ollignon, ;9"F, &issotia  stein+anni :isson, ;90F , & 1o)rneli 1Bayle, ;F03 , & alli @nechtel, ;9" and  Lenticeras lissoni 1@nechtel, ;9"3. =e considered this asse'blage broadly %antonian in age, later re&erred by Bengtson 1;9FF3 to #robably the early %antonian. =o)ever, a''onite syste'atics and international chronostratigra#hic correlations around the oniacian%antonian boundary re'ain i'#recise and even a late oniacian age 'ust be considered #ossible, es#ecially in vie) o& the &act that the genus &issotia is not de&initely *no)n &ro' #ost5oniacian levels 1<right, ;993.

 A late oniacianearly %antonian age &or the 'iddle #art o& the elendIn >or'ation ss is su##orted by the a##earance o& the bivalves  Plat(cera+)s c(cloides 1R.;2"3 o& %antonianearly 4aastrichtian age and Cordicera+)s e- gr. +)elleri 1>ig. 23. 366 *c)ador 

>ro' the southern #art o& the 6riente Basin 1>ig. 3, =obbs 1;93 'entioned a tissotiid a''onite. n the northern #art o& the basin 1rIo Muios3, 4onciardini et al. 1;9F"3 deter'ined a %antonian &ora'ini&eral association )ith  Dicarinella concavata 1Brot(en, ;9"3 1a&&. as(+etrica 1%igal, ;9233, D. c&. ventricosa 1<hite, ;92F3, and several s#ecies o&  Mar2inotr)ncana in a 205'5thic* succession. n addition, detailed 'icro#alaeontological studies 1'ainly o& #alyno'or#hs3 have indicated a %antonian age &or the u##er #art o& the u##er 8a#o >or'ation 1e.g. Robertson Research, ;9FF! see revie) in Jaillard, ;99a3. n southeastern Ecuador 1%antiago4orona road3, an isolated outcro# o& 'arls and li'estones 19".3 yielded a  Re2inaites s#. 1%antonianlo)er a'#anian! @linger and @ennedy, ;9F0! <right, ;993 associated )ith  Plicat)la 1err(i o7uand, ;F2,  P(cnodonte 1lic<i Pervin7uire, ;9;2, and oniacian%antonian echinoids, )hich ta*en together suggest a %antonian age. Although )ell5e-#osed &ield sections are lac*ing, the occurrence o& these s#ecies and the 'icro#alaeontological data collected &ro' )ells 1revie) in Jaillard, ;99a3 suggest that the late oniacianearly %antonian transgression reached #art o& the 6riente Basin. 33 Late @antonian?earl( Ca+:anian +a$i+)+ 1loodin2 ev ent 

n the Pongo de Rente'a section 1>ig. 23, )e have &ound no a''onites o& %antonian or younger age  in sit), although the highest levels e-#osed o& the elendIn >or'ation have yielded &rag'ents o& s'ooth, &lat s#henodiscids 1R.;0, R.;;! >ig. 23 together )ith “unty#ical” tissotiids, )hich see's to indicate a &aunal change. A @)b+ortoniceras s#. 1"93 collected by PetroPerO geologists &ro'  ' above their last tissotiid s#eci'en but so'e 0 ' belo) our de&inite last occurrence o& this ta-on 1R.;2F3 'ay derive &ro' stratigra#hically higher beds e-#osed in the vicinity. %i'ilarly, a s#henodiscid 1;3 collected by 6-y geologists &ro' near the to# o& the 'arine se7uence 'ay also have co'e &ro' higher levels. n the 6riente Basin o& Ecuador, the u##er #art o& the 45; %hales 1u##er 8a#o >or'ation, >ig. 3 locally co'#rises 'arine shel& shales and &ine5grained sandstones, individuali(ed as a distinct sedi'entary body 1Rivadeneira et al., ;993. n the central  #art o& the basin, this unit yielded an association o& #alyno'or#hs, dinocysts and &e) nanno&ossils, )hich indicate a late %antonian to earliest a'#anian age 1Raynaud et al., ;99! Robertson Research, ;993. As these beds are se#arated &ro' the over5 and underlying beds by uncon&or'ities 1Raynaud et al., ;99! Robertson Research, ;993, they #robably re#resent transgressive to 'a-i'u' &looding de#osits. =o)ever, since the contact )ith the overlying sandstones is erosional, these de#osits are only locally *no)n. 3" Mid to earl( late Ca+:anian +a$i+)+ 1loodin2 event 

n the eastern basins, 'assive transgressive sandstones 1lo)er Vivian >or'ation o& the 4araCn Basin, 45; %andstones o& Ecuador, >ig. 3 are overlain by a thin layer o& 'arine shales )hich have yielded #alyno'or#hs suggesting the 'iddle  part of the a'#anian 1in Peru %alas, ;99;! 4athalone and 4ontoya, ;99! in Ecuador 4ills, ;92! Robertson Research, ;9FF! ;99! Raynaud et al., ;99! see revie) in Jaillard, ;99a3. /his transgression is )ell 'ani&ested in the Bagua area o& northern Peru

F 14ourier et al., ;9FF3, )here the u##er levels o& the elendIn >or'ation contain the a''onites Mana+bolites s#. and Lib(coceras s#. 1abundant3, associated )ith  Menabites s#., @)b+ortoniceras s#. and  Pac(disc)s s#. uv. 1Bengtson, ;9FF3, the latter ta-on no) reassigned to  Men)ites s#. ollecting by J. Jacay 1+niv. %an 4arcos, :i'a3 in the Bagua Basin 1in ;99"3 yielded a very si'ilar &auna &ro' ?allo antana, ca. 20 *' south o& Bagua 1>ig. ;3. 35 *arl( Maastrictian +a$i+)+ 1loodin2 event 

n the eastern basins o& Peru and Ecuador, thin 'arine layers re#resenting an early 4aastrichtian 'arine transgression have long been recogni(ed. >ro' the achiyacu >or'ation o& Peru 1>ig. ;03, a @:enodisc)s s#. 1Rodrigue( and halco, ;93, an undeter'ined a''onite 1Vargas, ;9FF3 and early 4aastrichtian 'icro&ossils 1?utierre(, ;9! 4Sller and Aliaga, ;9F;3 have been re#orted. /his unit is traditionally re&erred to the early 4aastrichtian 1@u''el, ;9"F! %alas, ;99;! 4athalone and 4ontoya, ;993. 4arine de#osits o& co'#arable lithology and &aunal content have been described &ro' the East5Peruvian Basin o& central 1@och and Blissenbach, ;92! Robertson Research, ;9903 and southern Peru 1Dvila and Ponce de :eCn, ;9;! %oto, ;9F23 and &ro' the Alti#lano o& southern Peru 1Jaillard et al., ;993 and Bolivia 1%e'#TrT et al., ;993. /he /ena >or'ation o& the 6riente Basin 1Ecuador, >igs.  and ;03 has locally yielded the #lan*tonic &ora'ini&ers Globotr)ncana c&. la::arenti Brot(en, ;9,  R)2o2lobi2erina c&. r)2osa 1Plu''er, ;923 1%igal, ;99! 4ills, ;92! Bristo) and =o&&stetter, ;93, Globotr)ncana ae2(:tica 8a**ady, ;90 and G :l)++erae 1?andol&i, ;93 1<hitta*er and =odg*inson, ;993, suggesting the u##er #art o& the lo)er 4aastrichtian. 4ore recently, detailed studies o& #ollen and dino&lagellates led Raynaud et al. 1;993 to ascribe the basal #art o& the /ena >or'ation 1Basal /ena unit3 to the lo)er 4aastrichtian. >inally, along the %antiago4orona road in southern Ecuador 1F. *' east o& the rIo Uau#i3, )e collected t)o a''onites &ro' the base o& the /ena >or'ation, identi&ied as Pac(disc)s e- gr. ne)ber2ic)s o& early 4aastrichtian age. 4arine bivalves and unidenti&iable large a''onites have been re#orted &ro' shel& de#osits o& the southern #art o& the subandean (one o& Ecuador 1 “:i'Cn >lysch”3, dated )ith 4aastrichtian &ora'ini&ers 1>aucher et al., ;9;! Bristo) and =o&&stetter, ;93. /hese de#osits 'ay have been de#osited in an e'bay'ent o& the &orearc (one, connected to the eastern “6riente” Basin. /hus, the early 4aastrichtian 'a-i'u' &looding event a##ears to have been a 'aor 'arine transgression in the eastern #art o& the Andean Basin. %. Post#$uronian transgressions in the forearc basins

/he stratigra#hy o& the &orearc (ones o& northern Peru and southern Ecuador has  been studied by %igal 1;993, @ennerley 1;93 and Bristo) and =o&&stetter 1;93 in south)estern Ecuador! and ddings and 6lsson 1;92F3, 6lsson 1;9", ;9""3, >isher 1;93, Reyes and aldas 1;9F3 and Reyes and Vergara 1;9F3 in north)estern Peru. /he &orearc (one co'#rises t)o successive sedi'entary basins o& retaceous age, se#arated by a regional uncon&or'ity related to the GPeruvianH tectonic #hase 1Jaillard et al., ;99! ;9993. /he “elica:ancones basin ” is a tectonically active Albianoniacian trough in&illed 'ainly by turbidites. /he basin is located in north)estern Peru and south)estern Ecuador, bet)een a volcanic arc to the east and southeast and the Palaeo(oic A'ota#e/ahuin 'assi& to the )est and north)est 1>ig. "3. /here&ore, the )estern succession constitutes the sedi'entary cover o& the A'ota#e/ahuin 4assi&, )hereas the eastern succession co'#rises volcanic5arc roc*s and related volcaniclastic

9 sedi'ents o& #robably Albian age.

!ig. %: ?eological s*etch 'a# o& the Paita and elica:ancones areas, )ith location o& the

'ain sections and localities cited in the te-t 1the /alara, /u'bes and %echura Basins are /ertiary Basins3.

/he sedi'ents o& the “elica:ancones basin ” are discon&or'ably overlain by the  88E5trending “PaitaUunguilla &orearc basin ” 1&or'erly included in the “elica  :ancones basin ”3, the a'#anian4aastrichtian sedi'ents o& )hich onla# onto the )estern A'ota#e/ahuin 4assi& and the eastern volcanic arc. /he basin e-tends into northern Peru to the %outh and )estern Ecuador to the 8orth. /he a'#anian transgressive sedi'ents o& the basin rest discon&or'ably on Palaeo(oic roc*s 1Paita area3, on de&or'ed Albian and +##er retaceous roc*s 1 “elica:ancones basin”3, and on de&or'ed, accreted oceanic roc*s o& retaceous age 1)estern ordillera o& Ecuador3. t is to be e-#ected, there&ore, that the tectonic activity disturbed the eustatic signal in these areas. "# Latest &)ronian?Coniacian +a$i+)+ 1loodin2 events

/he youngest &ossils #reviously re#orted &ro' the “elica:ancones basin ” are the latest /uronian a''onites c&.  Barroisiceras aber1ellneri 1Petersen, ;9"93 and  Barroisiceras s#. 1Reyes and Vergara, ;9F3 and a “%enonian” 'icro&auna 1<eiss, ;93 &ound in drill5holes, )ithout #recise stratigra#hic location. 8ear Angolo in northern Peru )e collected a loose i'#ression o&  Prote$anites c&. c(cni 1van =oe#en, ;93 100.A."Eb3, a s#ecies re&erred to the early oniacian by @linger and @ennedy 1;9F03. /hus, these &aunas a##arently belong to the latest /uronian5early oniacian transgression in this turbiditic trough.

;0 %antonian de#osits a##ear to be absent, #robably as a result o& de&or'ation and erosion related to the GPeruvianH tectonic #hase, )hich se#arates the evolution o& the “elica:ancones” and “PaitaUunguilla” basins 1>ig. 3.

!ig. &: %ections in the )estern 1Puyangoa(aderos3 and eastern 1RIo Playas3 #arts o& the

“elica:ancones

ta-a.

basin” in southern Ecuador 1>ig. "3, )ith location o& the 'ain diagnostic

"6 Late @antonian?earl( Ca+:anian +a$i+)+ 1loodin2 ev ent 

n the “elica:ancones basin ”, east o& the elica area 1rIo Playas section3, volcanic and volcaniclastic roc*s o& the Albian1K3 'ag'atic arc are uncon&or'ably overlain by 'arine 'arls, shales and sandstones o& the El 8arano >or'ation 1>ig. 3. /he basal, transgressive #art o& these beds have yielded  Plesiote$anites *)te$anitesE  se$t)berc)lat)s @linger N @ennedy, ;9F0 1P6.;;"3 and @)b+ortoniceras s#. 19.;3, suggesting an early a'#anian age 1>ig. 3. Associated bivalves 1 &ri2onarca s#.,  Pano:ea s#., Pse)doc)c)llaea lens %olger, ;903, and a &e) diagnostic nanno&ossils 1 Mic)la dec)ssata Ve*shina, ;99, )adr)+ 2artneri Prins N Perch58ielsen, ;93 are consistent )ith this age 1Jaillard et al., ;99! PTre( and Reyes, ;99! Bengtson and Jaillard, ;993. %ince these early a'#anian 'arine beds are only recorded in this area, a tectonic origin &or this locali(ed transgression is #robable. "3 Mid to late Ca+:anian trans2ression "3# Paita area

/he :a 4esa section, southeast o& Paita 1>ig. "3, co'#rises three lithologic units 1>ig. 3. /he lo)er unit consists o& transgressive shales, sandstones and li'estones )ith a''onites o& the genus Coa)ilites 19.:4.3 indicating an age not older than late a'#anian. /he bivalves  A+bi2ostrea villei 1o7uand, ;F23 19.:4.;, 9.:4., 9.:4., 9.:4.2, 9.:/.", 9.;3 and  Plicat)la arrisiana 6lsson, ;9" 19.:4., 9.;3 indicate the a'#anian4aastrichtian interval. /he 'iddle unit is re#resented by 'assive rudist5 1radiolitids3 and gastro#od5  bearing shel& li'estones, lac*ing diagnostic &aunas.

;; /he u##er unit consists o& 'arls intercalated )ith li'estone and sandstone beds, the lo)er #art o& )hich yielded  ostoceras s#. 19.:4.23 and Lib(coceras s#. 19.:4.23 as )ell as other s#henodiscid a''onites. /he genus  ostoceras indicates a late a'#anian age, a dating su##orted by the associated bivalve &auna 1e.g.,  Plicat)la arrisiana 19.;3, Catacera+)s a&&. 2old1)ssian)s 19.;, 9.;9Eb, P6."3 and the rudists belonging to the genera  Biradiolites, Radiolites and Praebarretia3 1>ig. 3.

!ig. ': %ection o& the :a 4esa >or'ation in the Paita area o& north)estern Peru, )ith

location o& diagnostic ta-a.

"36 Celica-Lancones area

n the RIo Playas section, the &ine5grained 'arls o& the u##er El 8arano >or'ation re&lect a ne) )ides#read 'arine transgression 1>ig. 3. /hese beds have yielded the a''onites  Men)ites s#. 1P6.;93 and *$itelocerasK s#. 1P6.;9, P6.9F3 o& a'#anian age, associated )ith the %antonianearly 4aastrichtian  Plat(cera+)s c&. c(cloides 1P6.2;3 and )ith 'icro&ossil asse'blages 1radiolarians, &ora'ini&ers, nanno&ossils3 o& late a'#anian to 4aastrichtian age 1Jaillard et al., ;99! ;9993. n the central 1La#otillo, :ancones3 and )estern #arts 1Angolo3 o& the elica  :ancones area, the early :ate retaceous turbidites are overlain uncon&or'ably by  blac* shales )ith li'estone nodules and ar*osic beds 1La#otillo >or'ation o& Ecuador, Angolo >or'ation o& Peru3. /hese yielded a #achydiscid a''onite 100.A.0Eb3 and @)b+ortoniceras s#. 19.", 9., 9.e."3, )hich indicate an age bet)een late %antonian and 'id a'#anian. At Puyango 1Ecuador3, transgressive li'estones resting on de&or'ed Albian li'estones have yielded a #oorly #reserved te-anitinaeK 19.03 and a Men)ites s#. 1P6.""Eb3 collected loose. n the 4onte ?rande area in Peru, in a &ault5bounded outcro# o& shales ascribed to the Angolo >or'ation, )e collected  *$iteloceras s#. 19.4?.23 o& a'#anian age. n the entire area, the La#otillo and Angolo &or'ations are characteri(ed by the large inocera'id Plat(cera+)s s#. 19.", 9.;9, 9.20, 99.A.;9Eb, 99.A.20Eb, 99.A.22Eb, 00.A.0FEb, 00.A.;F, 00.A.;9, 00.A.203 and  P c&. c(cloides 19.$3 o& %antonianearly 4aastrichtian age, associated )ith scarcer &rococera+)s s#. 19.203 1latest a'#anian'iddle 4aastrichtian3, &rococera+)s a&&. +ontic)li 1>ugger N @astner, ;FF3 19.$3 1latest a'#anianearly 4aastrichtian3 and Catacera+)s c&.  2old1)ssian)s 1dQ6rbigny, ;F"3 19.;9Eb3 1late a'#anian3.

;2 As a )hole, this asse'blage suggests a 'id to late a'#anian age 1>ig. 3. "33 estern *c)ador

n the )estern ordillera o& central Ecuador, the 4aastrichtian Uunguilla “>lysch” locally contain interbeds o& calciturbidites 1%an Juan :i'estones3, )hich are dated as a'#anian to early 4aastrichtian 1/hal'ann, ;9"! @ehrer and @ehrer, ;993. Part o& the Uunguilla >or'ation 'ay be coeval )ith the 'iddle to late a'#anian transgression. "" *arl( to +id Maastrictian trans2ressions ""# Paita area

/he :a /ortuga section, south o& Paita 1>ig. "3, co'#rises t)o &or'ations. /he :a /ortuga >or'ation consists o& a##ro-i'ately "000 ' o& red breccias, )hich include a shaly interval re#resenting a 'arine transgression 1:a /ortuga Beds o& 6lsson ;9"", 4iddle +nit in >ig. 3. >urther north)est, the eni(o >or'ation consists o& discon&or'able coarse5grained sandstones and subordinate conglo'erates. /hese roc*s rest directly on Palaeo(oic roc*s.

!ig. (: %ection o& the :a /ortuga and eni(o &or'ations in the Paita area o&

north)estern Peru, )ith location o& diagnostic ta-a.

; /he 4iddle +nit o& the :a /ortuga >or'ation has yielded @:enodisc)s s#. 100.:/.93 and nu'erous bivalves, ascribed to the a'#anian4aastrichtian boundary interval 1>ig. 3. /he :a /ortuga u##er breccias are ca##ed by transgressive, &ossili&erous yello) sandstones 1Baculites %andstones o& 6lsson, ;9"", lo)er eni(o >or'ation in >ig.  and F3, )hich have yielded nu'erous  *)bac)lites c&. carinat)s 14orton, ;F"3 19.:/.23 and one 9(:o:(lloceras eo:(llocerasE s)r(a 1>orbes, ;F"3 19.:/.23 o& 4aastrichtian age 1Bengtson and Jaillard, ;993, #robably early 4aastrichtian 1c&. ourville and 6din, 200;3. Associated )ith these a''onites there are nu'erous )ell5  #reserved bivalves, a'ong )hich &rococera+)s c&. naorianensis @ociubyns*i, ;9F 19.:/.23 indicates a late a'#anian to early 4aastrichtian age 1Dhondt and Jaillard, in  #ress3. %a'#le 00.:/." &ro' the sa'e unit 'ight be either Inocera+)s sa2ensis 6)en, ;F2 o& a'#anian age, or 'ore #robably, a &rococera+)s s#., thus indicating a #re5 late 4aastrichtian age 1<alas(c(y* et al., 200;! <alas(c(y* et al., 2002a, 2002b3.

!ig. ): %ection o& the eni(o >or'ation in the Paita area o& north)estern Peru, )ith location

o& diagnostic ta-a.

/he u##er #art o& the eni(o >or'ation 1Radiolites %andstones o& 6lsson, ;9""3 overlies dar*5coloured conglo'erates. ts lo)er #art yielded  Pac(disc)s c&. e:i:lect)s 1Redtenbacher, ;F3 199.%.3,  P dossantosi 14aury, ;903 199.%.9Eb3 and  *)bac)lites s#. 100.:/.3 suggesting an early 4aastrichtian age. Bivalves include the inocera'id &rococera+)sK s#. and nu'erous rudists belonging to the genus  Mac2illavr(ia. /he 'iddle #art o& the eni(o >or'ation thus see's to be early 4aastrichtian in age 1>ig. F3. According to these data, the older transgression 1'iddle :a /ortuga >'3 can be dated as late a'#anian, and the succeding ones 1lo)er and 'iddle #arts o& eni(o >'3 as early 4aastrichtian.

;" ""6 Celica?Lancones area

/he a'#anian La#otillo and Angolo >or'ations are overlain by thic*, coarse5 grained conglo'erates 1/ablones >or'ation3, in turn overlain by shales )ith li'estone nodules and intercalations o& 7uart(5rich, 'ediu'5grained turbidites 1a(aderos >or'ation in Ecuador, Pa(ul >or'ation in Peru, >ig. 3. n the )estern #art o& the area, these beds locally cover directly the Albian transgressive beds. n the a(aderos area 1Ecuador3, the a(aderos >or'ation has yielded  Di:lo+oceras s#. 19., P6."F23,  *$iteloceras s#. 1P6."F23, and an unidenti&iable large #achydiscid 19."0Eb3 collected loose. n the sa'e area, )e collected  Plat(cera+)s s#. 1P6."F2, 99.A.;;Eb3 o& oniacianearly 4aastrichtian age. /his &auna and the stratigra#hic relationshi#s are consistent )ith a late a'#anianearly 4aastrichtian age. ""3 estern *c)ador

n the <estern ordillera o& central Ecuador 1>ig. ;3, the shales and turbidites o& the Uunguilla >or'ation ss are dated )ith &ora'ini&ers as 4aastrichtian 1/hal'ann, ;9"! %igal, ;99! Bristo) and =o&&stetter, ;9! Pratt et al., ;99F3. n the <estern ordillera, at ; °"% 1near =uangu#ud3, )e collected the a''onites *$iteloceras s#. 199.?.", 99.?.3 o& a'#anian age, and  9(:o:(lloceras 1 eo:(lloceras3 s#. 199.?.3, co'#arable to  9 E s)r(a &ro' the lo)er El eni(o >or'ation o& northern Peru 1see above3. /his association su##orts a late a'#anianearly 4aastrichtian age &or the Uunguilla >or'ation. n the uenca area 1>ig. ;3, the a''onites @:enodisc)s :er)vian)s ?erth, ;92F and @olenoceras s#. indicate an early 4aastrichtian age &or #art o& the Uunguilla >or'ation 1=o)arth, in Bristo) and =o&&stetter, ;9! Pratt et al., ;99F3. n that region, a &e) *ilo'etres %%E o& A(ogues, )e collected a &rag'ent o& a Gl(:to$oceras s#. 1%antonian4aastrichtian! <right, ;993 or  eo2l(:to$oceras s#. 1lo)er'iddle a'#anian! <right, ;993. ;2 *' E8E o& uenca 1El Descanso3, )e collected a  Di:lo+oceras s#. 1late a'#anian4aastrichtian! @Schler and 6din, 200;3 102..23, and t)o &rag'ents 102..3 o& Gl(:to$oceras s#. or eo2l(:to$oceras s#. According to these data, the Uunguilla >or'ation is 'ost #robably o& late a'#anian to early 4aastrichtian age, and there&ore coeval )ith the 'arine transgressions recogni(ed in the Paita and elica:ancones areas. &. Correations and tectonic impications

Ages &or the 'a-i'u' &looding events are those a##lied to Euro#ean basins as deter'ined by =ardenbol et al. 1;99F3, )ho also revised the relative sea5level 'a-i'a o& =a7 et al. 1;9F3. 5# &)ronian?Coniacian

A latest /uronian to early oniacian 'a-i'u' &looding event is clearly 'ani&ested in the bac*arc basins on the basis o& data &ro' the rIo 4isahuallI and Rente'a sections. Because o& late Albian and %antonian de&or'ations, the event is  #oorly e-#ressed in the &orearc (ones. /his latest /uronianearly oniacian 'a-i'u' &looding event is #oorly docu'ented in the Andean areas, although oniacian 'arine &aunas are )idely *no)n. A signi&icant 'a-i'u' &looding event is 'entioned by =a7 et al. 1;9F3 and =ardenbol et al. 1;99F3 near the /uronianoniacian boundary 1F9FF. 4a3, )hich &its )ell )ith our data 1>ig. 93. /he end o& the carbonate shel& sedi'entation and the beginning o& the &ine5 grained clastic sedi'entation is dated as latest /uronianearliest oniacian in Ecuador

; 14isahuallI3 and as late /uronian in the Rente'a area in Peru. /his change in sedi'entation has been inter#reted as the beginning o& the GPeruvianH tectonic #hase 1Jaillard, ;99"! %e'#TrT, ;99"3. 56 @antonian

A %antonian 'a-i'u' &looding event is locally 'ani&ested in the eastern basins o& Ecuador and northern Peru. According to the &aunas collected at Pongo de Rente'a, it see's to be o& late oniacianearly %antonian age. 8o %antonian 'a-i'u' &looding event is *no)n to have occurred in the &orearc (ones o& northern Peru and Ecuador but an early %antonian transgression has been identi&ied in the &orearc (one o& southern Peru 1Vicente, ;9F;! Jaillard, ;99"3. /ransgressions or high sea5level #eriods o& %antonian age are *no)n in olo'bia &ro' the u##er 4agdalena Basin 1Vergara, ;993 and the eastern basin 1?uerrero and %ar'iento, ;993, and in Vene(uela 1=elenes et al., ;99F! =elenes and %o'o(a, ;9993. /he earliest %antonian age o& the eustatic 'a-i'u' &looding 1ca. FF 4a3, 7uoted by =a7 et al. 1;9F3 and =ardenbol et al. 1;99F3, is consistent )ith our data 1>ig. 93. Because o& the u#li&t during the GPeruvianH tectonic #hase, the 'iddle %antonian to early late %antonian 'a-i'u' &loodings 'entioned by =a7 et al. 1;9F3 and =ardenbol et al. 1;99F3 are un*no)n on the Andean 'argin o& northern Peru and Ecuador.

!ig. *: o'#arison bet)een 'arine transgressions recogni(ed in northern Peru and Ecuador

and eustatic sea5level &luctuations identi&ied by =a7 et al. 1;9F Wrecalibrated by =ardenbol et al., ;99FX3 and =ardenbol et al. 1;99F3. 53 Ca+:anian

A late %antonianearly a'#anian 'a-i'u' &looding event has been recogni(ed only in the eastern #art o& the elica:ancones area and locally in the central #art o& the 6riente Basin o& Ecuador 1u##er #art o& the 45; %hales, belo) the 45; %andstones3. n the elica:ancones area, it overlies uncon&or'ably volcanic roc*s de&or'ed by the 'id and :ate retaceous tectonic events. n the 6riente Basin it &ollo)s a de#ositional  brea* co'#rising #art o& the %antonian 1Raynaud et al., ;99! Robertson Research,

; ;993. /his late %antonianearly a'#anian 'arine transgression )as #robably enhanced by tectonic subsidence, and see's to re#resent the &irst stage o& the regional a'#anian transgression that conceals the GPeruvianH de&or'ations. An early a'#anian 'a-i'u' &looding event is locally *no)n, &or e-a'#le, &ro' the eastern basin o& northern olo'bia 1%an Antonio >or'ation, ?uerrero and %ar'iento, ;993 and the eastern ?ul& oastal Plain o& 8orth A'erica 14ancini et al., ;993, but has not been identi&ied in Vene(uela 1=elenes et al., ;999! =elenes and %o'o(a, ;9993. /his transgression 'ight corres#ond to the 'aor transgression identi&ied by =a7 et al. 1;9F, recalibrated by =ardenbol et al., ;99F3 and =ardenbol et al. 1;99F3 near F.F 4a 1>ig. 93. /he &act that this 'aor transgression is only locally 'ani&ested indicates that the Andean 'argin )as already u#li&ted and de&or'ed  by the GPeruvianH de&or'ations. /he 'id a'#anian to early late a'#anian transgression )as a 'aor event that de&initely concealed the GPeruvianH de&or'ations. According to available data, this transgression is 'ani&ested in the eastern basins o& Ecuador 145; %andstones3 and Peru 1lo)er Vivian >or'ation3 and in the &orearc (ones o& north)estern Peru 1:a 4esa >or'ation3, and south)estern Ecuador 1u##er El 8arano >or'ation3. >urther south, thin 'arine layers containing selachians, scarce bivalves and charo#hytes have been correlated )ith the 'id a'#anian to early late a'#anian transgression 1Jaillard et al., ;993. n the &orearc (ones, this )ides#read transgression see's to have been characteri(ed by the de#osition o& o#en5'arine shel& li'estones. Because e'ergence occurred a&ter the early %antonian at Pongo de Rente'a 1see also Bengtson, ;9FF3, the age o& the GPeruvianH tectonic #hase )ould be brac*eted bet)een 'id %antonian and 'id a'#anian ti'es. /he 'id to early late a'#anian transgression is *no)n in the )hole East5 Paci&ic area, &ro' the Antarctic Peninsula 1As*in et al., ;99;3 and Argentina 1:agarreta et al., ;9F9! Barrio, ;9903 to olo'bia and Vene(uela 1Barrio and o&&ield, ;992! ?uerrero and %ar'iento, ;99! Vergara, ;99, =elenes et al., ;99F3 and entral and  8orth A'erica 1e.g. ?ill and obban, ;9! 4olenaar and Rice, ;9F9! 4ichaud et al., ;9923. t is also 'ani&ested in the %outh Atlantic basins, &or e-a'#le in the %ergi#e Basin 1Bengtson et al., ;993 and the Perna'bucoParaIba Basin 14uni(, ;993. Because the “'id” a'#anian 'a-i'u' &looding event reached the tectonically stable eastern basins o& the Andean 'argin, it #robably coincides )ith a signi&icant eustatic sea level rise. According to =a7 et al. 1;9F3 and =ardenbol et al. 1;99F3, 'id and late a'#anian ti'es )ere 'ar*ed by a high average sea level and by three sea5level rises. As the late 'id a'#anian 1ca. F 4a3 and late a'#anian 1ca. . 4a3 'a-i'u' &looding events are considered 'ore signi&icant 1=ardenbol et al., ;99F3, they 'ay correlate )ith the 'a-i'u' &looding events recogni(ed in this study 1>ig. 93. /he &act that this transgression is 'uch 'ore clearly 'ani&ested in the &orearc (ones than in the eastern basins suggests that it )as rein&orced by a tectonically driven subsidence o& the &orearc (ones o& northern Peru and Ecuador. 5" Maastrictian

An early 4aastrichtian transgression is 'ani&ested in the &orearc (ones o& north)estern Peru 1lo)er eni(o >or'ation3 and )estern Ecuador 1Uunguilla >or'ation3, in the 6riente Basin o& Ecuador 1base o& /ena >or'ation, “>lysch :i'Cn”), and the East5Peruvian Basin 1>undo el /riun&o and achiyacu &or'ations! 4ourier et al., ;9FF! 4athalone and 4ontoya, ;993. /he transgression has been identi&ied in 'ost o& the eastern areas o& Peru 1Areniscas de A(Ocar, Pu7uIn and u##er Vil7uechico >or'ations! @och and Blissenbach, ;92! Jaillard et al., ;99! arlotto, ;99F3, and in Bolivia 1El 4olino >or'ation3, )here it is dated as early 4aastrichtian by  #alaeo'agnetis' cou#led )ith one radio'etric date 12 4a, %e'#TrT et al., ;993. =o)ever, in 'any eastern areas, stratigra#hic data are not accurate enough to deter'ine

; )hether this transgression correlates )ith the early 4aastrichtian transgressions recogni(ed in the &orearc (ones. n the northern #art o& the Ecuadorian %ubandean (one 1Ber'eo3, ho)ever, the 4aastrichtian /ena >or'ation see's to record successive 'arine transgressions 1>aucher et al., ;9;! Jaillard, ;99a3.

!ig. 1+: /entative correlation o& the 'ain 'a-i'u' &looding events, considered as ti'e5

lines, across the Andean 'argin.

Early 4aastrichtian transgressions are )ell *no)n &ro' the %alta 1%al&ity and 4ar7uillas, ;99"3, 8eu7uTn 1:agarreta et al., ;9F9! Barrio, ;9903 and 4agallanes 1Biddle et al., ;9F3 basins o& Argentina 1see 4alu'in and Ra'os, ;9F"! +liana and Biddle, ;9FF3 and are also )ell docu'ented in northeastern olo'bia 1?uerrero and %ar'iento, ;993, Vene(uela 1=elenes et al., ;99F3, 8orth A'erica 1?ill and obban, ;9! 4olenaar and Rice, ;9F93 and on the Paci&ic guyots, )here Arnaud5Vanneau et al. 1;993 recogni(ed t)o 'a-i'u' &looding events o& early 4aastrichtian age 1se7uence boundaries at " and ; 4a, res#ectively3. /hese data indicate that the )ides#read early 4aastrichtian 'a-i'u' &looding event recogni(ed on the Andean 'argin coincides )ith a 'aor eustatic rise, )hich could corres#ond to the earliest 4aastrichtian 'aor 'a-i'u' &looding event o& =a7 et al. 1;9F3 1; 4a according to calibration by =ardenbol et al., ;99F! >ig. 93. According to =ardenbol et al. 1;99F3, the early 4aastrichtian, 'aor 'a-i'u' &looding event is younger 1ca. 9. 4a3. :ater 4aastrichtian transgressions have been recogni(ed in southern Argentina 1Austral and 8eu7uTn basins, e2 Biddle et al., ;9F! Barrio, ;9903, in eastern olo'bia 1?uaduas >or'ation, Barrio and o&&ield, ;992! ?uerrero and %ar'iento, ;993, in Vene(uela 1=elenes and %o'o(a, ;9993 and in southern 8orth A'erica 1early late 4aastrichtian, 4ancini et al., ;993. =o)ever, because o& #oor biostratigra#hic control and only local records, correlation bet)een these events is di&&icult. =ardenbol et al. 1;99F3 'ention a signi&icant 'a-i'u' &looding event during the late early 4aastrichtian 19. 4a3, )hich 'ight correlate )ith the late1K3 early 4aastrichtian u##er eni(o transgression o& north)estern Peru. onglo'erates and turbidites characteri(e the 4aastrichtian de#osits o& the &orearc (ones o& northern Peru and southern Ecuador. n north)estern Peru, the late a'#anian transgressive 'arls, li'estones and sandstones o& the u##er :a 4esa

;F >or'ation grade into shel& sandstones and conglo'erates. /he late a'#anianearly 4aastrichtian :a /ortuga >or'ation consists o& a 005'5thic* series o& breccias 16lsson, ;9""! Bengtson and Jaillard, ;993. n the elica:ancones area, the late a'#anian beds 1Angolo, La#otillo and El 8arano &or'ations3 are con&or'ably overlain by coarse5grained conglo'erates 14onte ?rande and asanga &or'ations, res#ectively! 6lsson, ;9"! Baudino, ;99! Jaillard et al., ;99! ;9993, in turn overlain  by early 4aastrichtian de#osits 1Pa(ul and a(aderos &or'ations3. n these &orearc areas, the lac* o& younger de#osits suggests that they beca'e e'ergent by 'iddle to late 4aastrichtian ti'es. n the ordillera o& Ecuador, the early 4aastrichtian is 'ar*ed  by turbiditic de#osits 1Uunguilla >or'ation3, and no late 4aastrichtian beds have been identi&ied. n the bac*arc basins, the late 4aastrichtian is 'ar*ed either by de#osition o& &ine5grained redbeds or by hiatuses 1Jaillard, ;99a3. %uch coarse5grained de#osits e-#ress an i'#ortant tectonic activity in the &orearc (one, )hich could be related to ra#id )rench 'ove'ents evidenced bet)een 0 and 0 4a in the arc (one o& central and northern Peru 1Bussel and Pitcher, ;9F3. A late 4aastrichtian tectonic activity is &urther docu'ented by a ther'al event 10 4a! :itherland et al., ;99"3 and by a ra#id u#li&t around  4a 1%#i*ings et al., 200;3 recorded in the Eastern ordillera o& Ecuador, and by a latest 4aastrichtian de&or'ational #hase 'ani&ested in central olo'bia 1heillet( et al., ;993. /hey see' to correlate )ith the accretion o& an oceanic terrane *no)n in central Ecuador 1Jaillard et al., 200"3.  8o 'arine de#osits correlating )ith the 'aor early Danian sea5level rise 1=a7 et al., ;9F! >ig. 93 have been recogni(ed on the Andean 'argin. =o)ever, the #oor chronostratigra#hic data available &or the Paleocene subaerial de#osits do not allo) to correlate the' accurately )ith the tectonic and sedi'entary events recorded in the &orearc (ones. '. Concusions

1;3 %i- 'a-i'u' &looding events are recogni(ed on the Andean 'argin o& northern Peru and Ecuador 1>ig. ;03, vi(. 1;3 latest /uronianearly oniacian, 123 late oniacianearly %antonian, 13 early a'#anian, 1"3 'id a'#anianearly late a'#anian, 13 early 4aastrichtian and 13 ter'inal early 4aastrichtian. /he 'aor 'arine transgressions occurred in the latest /uronianearly oniacian, 'id a'#anian  early late a'#anian, and early 4aastrichtian, a #attern )hich coincides broadly )ith *no)n eustatic sea level rises 1>ig. 93. 123 Although 'ost o& the 'arine transgressions on the Andean 'argin coincide in ti'e )ith eustatic sea5level rises, their 'agnitudes do not corres#ond to those #redicted  by the eustatic charts o& =a7 et al. 1;9F3 and =ardenbol et al. 1;99F3 1>ig. 93. >or e-a'#le, the 'aor 'id a'#anianearly late a'#anian transgression on the Andean 'argin 'ay correlate )ith either the 'id a'#anian 1F. 4a3, or the early late a'#anian 1". 4a3 sea5level rises o& =ardenbol et al. 1;99F3, )hereas the 'aor latest %antonianearliest a'#anian eustatic transgression 1=a7 et al., ;9F! =ardenbol et al., ;99F3 has been only locally recorded on the Andean 'argin. /here&ore, regional or local tectonic 'ove'ents #robably account &or the absence o& traces o& the 'iddle %antonian, late a'#anian or early Danian sea5level rises on the Andean 'argin, and &or the enhance'ent o& the 'id a'#anian and early 4aastrichtian transgressions. 13 <ith res#ect to the tectonic evolution o& the Andean 'argin, the &ollo)ing results are e'#hasi(ed  5 >ine5grained clastic sedi'entation in the 6riente and East5Peruvian basins began in the 'id /uronianearliest oniacian 1>ig. ;03, and is ta*en as the &irst 'ani&estation o& the GPeruvianH tectonic #hase.

;9 5 /he a'#anian regional transgression in the PeruvianEcuadorian &orearc (ones concealed the GPeruvianH de&or'ational event, )hich occurred bet)een the late oniacian and 'id a'#anian 1>ig. ;03, 'ost #robably during the 'id %antonian  earliest a'#anian interval 1ca. FF2 4a3. 5 /he GPeruvianH tectonic #hase caused a #aleogeogra#hic u#heaval, indicated by the subse7uent develo#'ent o& a 88E5trending &orearc basin, )hich e-tended at least &ro' Paita to Muito 1°0%50°3. 5 n the &orearc (ones, only short5lived 'arine transgressions are recorded in the late a'#anian and 4aastrichtian, because o& a nearly continuous tectonic activity, )hich see's to cul'inate in the latest a'#anian. 5 A )ides#read, regional late 4aastrichtian uncon&or'ity suggests that a 'aor tectonic event a&&ected the )hole Andean 'argin at this ti'e 1F 4a! >ig. ;03. Acknowedgements

/his #a#er is an e-#anded and u#dated version o& the contributions by Jaillard 1;99b3 and Bengtson and Jaillard 1;993 to the %econd Euro#ean 4eeting on the Palaeontology and %tratigra#hy o& %outh A'erica, =eidelberg ;99. <e are indebted to Jean Phili# 14arseille3 and Didier 8Traudeau 1Rennes3, )ho assisted in dating so'e stratigra#hic units, to ?Trard :aubacher 14ont#ellier3 )ho contributed signi&icantly to the 'a##ing o& the elica:ancones area and to Javier Jacay 1:i'a3 &or collecting so'e o& the s#eci'ens &ro' the Bagua area. <e than* =ans :ang 1:ud)igsha&en3 &or #re#aration o& the a''onites and @arin Riedelsberger 1+niversitYt =eidelberg3 &or 'a*ing casts o& crucial s#eci'ens. RD 1&or'erly 6R%/64, >rance3 su##orted 'ost o& the &ield )or* and trans#ort o& sa'#les! costs &or the latter )ere also de&rayed by the +niversitYt =eidelberg. /his #a#er bene&ited &ro' discerning criticis' and co''ents by Annie Arnaud5Vanneau 1+niversitT Jose#h >ourier, ?renoble3 and >ran* <iese 1>reie +niversitYt, Berlin3. ,eferences

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