Beloc, Haiti, revisited: multiple events across the KT boundary in the Caribbean W. Stinnesbeck 1 , G. Keller 2 , T. Adatte 3 , D. Stu Èben 4 , U. Kramar 4 , Z. Berner 4 , C. Desremeaux 5 and E. Molie Áre 6 1 Geologisches Institut, Universita Èt Karlsruhe, 76128 Karlsruhe, Germany, 2 Department of Geosciences, Princeton University, Princeton, NJ, USA, 3 Institut de GeÂologie, 11 Rue Emile Argand, 2007, Neucha Ãtel, Switzerland, 4 Institut fu Èr Petrographie und Geochemie, Universita Èt Karlsruhe, 76128 Karlsruhe, Germany, 5 UFR Sciences de la Terre et de la Mer, Universite de Bordeaux 1, 33400 Talence, France, 6 Ecole Nationale de GeÂologie AppliqueÂ, Port-au-Prince, Haiti Introduction Glass spherules, shocked minerals and aniridiumanomalyinCretaceous±Ter- tiary(K/T)sedimentsnearBeloc,Haiti, are frequently cited as critical evidence in support of a large extraterrestrial impactatChicxulub,Yucatan,Mexico. The evidence consists of the chemical similarity of Haiti glass spherules, which are considered altered tektites (Izett etal. l990; Izett, l99l; Sigurdsson etal. l99l; Kring etal. l99l; Koeberl and Sigurdsson, l992; Koeberl, l992), with those at Mimbral, Mexico (Smit etal. l992; Stinnesbeck etal. l993) and melt rock in subsurface cores at Chicxulub (Koeberl,1993).Althoughmoststudies suggest that this evidence supports an impact at the K±T boundary, some authors have suggested that volcanism (Lyons and Officer, l992), two impacts (Leroux etal. l995), or one impact and one volcanic event JeÂhanno etal. l992) produced the glass spherules and iri- dium anomaly. Our work on the Beloc sections was prompted by a desire to reconcile the complex depositional se- quence observed in the Mexican sec- tionswiththatreportedfromHaiti(e.g. Maurrasse and Sen, 1991; JeÂhanno et al. l992; Leroux etal. l995). Location and methods The road from Port au Prince to Beloc and Jacmel was widened recently, ex- posing new roadcuts where Cretaceous and Tertiary rocks of all but one of the previously reported sections are ex- posed. All of the roadcut sections are intensely faulted, folded, and sheared parallel to or at small angles to the bedding plane. In particular, the K/T boundary clay is generally sheared, highly condensed, and the basal Da- nian is missing (Keller etal., in press). We collected at two K±T outcrops along the road of which one (B6) is the locality H of JeÂhanno etal. (1992) and Leroux etal. (l995), and the other (B1) is a newly exposed outcrop nearer toBeloc.About1kmnorthofBelocon a steep slope and 30±40 m below the road, a more complete K±T interval is preserved in a tectonic graben with no evidence of tectonic deformation. We collected along three K±T transects: section B2 is a poorly exposed outcrop that was described by Maurasse and Sen (l991); sections B3 and B4a are better exposed than B2 and located approximately 25 m and 60 m, respec- tively,tothenorthofB2alongthesame slope (Fig. 1). This study is based on biostratigra- phical, geochemical, and sedimentolo- gical analyses. Biostratigraphical age determinations are based on plank- tonic foraminifera that are common toabundantandwellpreservedinmost sampled sections. Samples were pro- cessed by standard techniques (Keller et al. l995) and washed through a 38 mmscreen.AllDanianspeciesarefound to be within the 38±63 mm size-fraction. This small size-fraction is generally dis- carded in standard sample processing and biostratigraphical analyses. Larger specimens appear only in the upper part of the Parvularugoglobigerina eugubina Zone [Pla(2)]. Analysis of the smaller size-fraction plus samples from weath- eredoutcropsmayexplainwhyprevious workers were unable to find Danian species close to or within the spherule- rich deposits (SRD) (Sigurdsson et al. l991;MaurasseandSen,l991;Leroux et al., 1995). Samples were also analysed for iridium and other Platinum Group Elements (PGEs) using ICP/MS (after preconcentration by nickel sulphide fire assay,Cubelic etal.,1997).Thinsections were made of all samples and lithologi- cal changes documented. Depositional sequence and biostratigraphy In 4 of the 5 Beloc sections examined (all except B2) pelagic marly limestone of late Maastrichtian age is present and contains radiolarians, calcispheres, sponge spicules, ostracods, benthic for- aminifera, and abundant planktonic foraminifera including Plummerita hantkeninoides (details of the biostrati- graphical study are published in Keller etal.,inpress).Theindexspecies Plum- * C 1999 Blackwell Science Ltd 303 ABSTRACT Examination of new expanded K/T boundary sections near Beloc, Haiti, reveals deposition of a glass spherule-rich deposit (SRD) and two (PGE) anomalies (one Ir-dominated and one Pd- dominated) during the early Danian Parvularugoglobigerina eugubina Zone [Pla(l)]. The presence of the Haiti SRD within the early Danian is interpreted as being due to reworking. Ir is only slightly elevated within the SRD but forms an anomaly at the top of the SRD extending into the overlying pelagic limestones. It is unclear at present whether this Ir anomaly results from mechanical reworking of an impact at the K/T boundary, or an additional impact event in the early Danian. The second PGE anomaly upsection is dominated by Pd and Pt and is more compatible with a magmatic origin. This suggests a multi-event scenario consistent with one (and possibly two) impact(s), followed by a PGE-enriched volcanic event in the Caribbean. Terra Nova, 11, 303±310, 1999 Ahed Bhed Ched Dhed Ref marker Fig marker Table marker Ref end Ref start *Correspondence: Tel: +49/7216082137, Fax: +49/7216082138; E-mail: wolfgang.- stinnesbeck@bio-geo.uni-karlsruhe.de Paper 263 Disc