Observation of charmless hadronic B decays

Four candidates for charmless hadronic B decay are observed in a data sample of four million hadronic Z decays recorded by the ALEPH detector at LEP. The probability that these events come from background sources is estimated to be less than 10(-6). The average branching of weakly decaying B hadrons (a mixture of B-d(0), B-s(0) and Lambda(b) weighted by their production The average branching ratio of weakly decaying B hadrons (a mixture of B-d(0) cross sections and lifetimes, here denoted B) into two long-lived charged hadrons (pions, kaons or protons) is measured to be Br(B-->h(+)h(-))=(1.7(-0.7)(+1.0)+/-0.2)x10(-5). The relative branching fraction Br(B-d(s)(0)-->pi(+)pi(-)(K-))/Br(B-d(s)(0)-->h(+)h(-)) is measured to be 1.0(-0.3-0.1)(+0.0+0.0). In addition, branching ratio upper limits are obtained for a variety of exclusive charmless hadronic two-body decays of B hadrons

An Early Cambrian archaeocyath–trilobite fauna in limestone erratics from the Upper Carboniferous Fitzroy Tillite Formation, Falkland Islands

Rare clasts of limestone contained in the uppermost Carboniferous Fitzroy Tillite Formation of the Falkland Islands contain a rich Cambrian fauna of archaeocyaths together with a radiocyath and a few trilobites. Neither Cambrian strata nor limestone are present in the indigenous rock succession and the clasts are regarded as exotic erratics, introduced during the Permo-Carboniferous glaciation of southern Gondwana, prior to its Mesozoic break-up. Nineteen archaeocyath taxa have been identified, with seven (plus a radiocyath) occurring in a single clast. Trilobite identifications are less definitive, but they are compared to Yorkella and the Siberian genera Edelsteinaspis, Namanoia and Chondrinouyina. The archaeocyath fauna has an Australo–Antarctic character and the Transantarctic Mountains seem the most likely source for these unusual erratics. Most recent reconstructions of Gondwana rotate a Falklands microplate into a position between South Africa and East Antarctica. There, it is in proximity with the Eastern Cape Province, where tillites within the Permo-Carboniferous Dwyka Group are correlatives of the Fitzroy Tillite Formation, and the ‘Atlantic’ end of the Transantarctic Mountains. The Dwyka Group tillites also contain rare clasts of archaeocyathan limestone and the rotational reconstruction produces a continuity of the apparent ice-flow directions in South Africa and the Falkland Islands

Archaeocyathan limestone blocks of likely Antarctic origin in Gondwanan tillite from the Falkland Islands

Cambrian limestone clasts containing a rich, well-preserved archaeocyathan fauna have been recovered from the late Carboniferous Fitzroy Tillite Formation of the Falkland Islands. Since neither Cambrian strata nor limestone are present anywhere in the indigenous rock succession, the clasts are regarded as exotic erratics introduced during the Permo-Carboniferous Gondwana-wide glaciation. Most recent reconstructions of Gondwana rotate the Falklands into proximity with the Eastern Cape, South Africa and the Ellsworth Mountains, Antarctica. In both of these areas, Permo-Carboniferous diamictites correlated with the Fitzroy Tillite Formation also contain rare, exotic clasts of archaeocyathan limestone. The Transantarctic Mountains seem the most likely source for all of these unusual erratics. This interpretation sustains the requirement for substantial rotation of the Falklands microplate into Gondwana reconstructions and illustrates the extent of the late Carboniferous ice sheet. Apparent differences in the tillite clast assemblages between East and West Falkland suggest variable provenance within the regional ice-flow regime

A comparison of the ammonite faunas of the Antarctic Peninsula and Magallanes Basin

Ammonite-bearing Jurassic and Cretaceous sedimentary successions are well developed in the Antarctic Peninsula and the Magallanes Basin of Patagonia. Faunas of middle Jurassic-late Cretaceous age are present in Antarctica but those of Patagonia range no earlier than late Jurassic. Although the late Jurassic perisphinctid-dominated faunas of the Antarctic Peninsula show wide-ranging Gondwana affinities, it is not yet possible to effect a close comparison with faunas of similar age in Patagonia because of the latter’s poor preservation and our scant knowledge of them. In both regions the Neocomian is not well represented in the ammonite record, although uninterrupted sedimentary successions appear to be present. Lack of correspondence between the Aptian and Albian faunas of Alexander I. and Patagonia may be due to major differences in palaeogeographical setting. Cenomanian-Coniacian ammonite faunas are known only from Patagonia, although bivalve faunas indicate that rocks of this age are present in Antarctica. Kossmaticeratid faunas mark the late Cretaceous in both regions. In Antarctica these have been classified as Campanian, whereas in Patagonia it is generally accepted, perhaps incorrectly, that these also range into the Maestrichtian