item 2007233, Appendix DR1 (section of the Salamanca Formation at Palacio de los Loros locality), Appendix DR2 (distinguishing features of angiosperm leaf morphotypes from Palacio de los Loros), and Appendix DR3 (relative abundance of dicot leaf morphotypes for rarefaction analysis), is available online at www.geosociety. org/pubs/ft2007.htm, or on request from editing@ geosociety.org or Documents Secretary, GSA,

The Tithonian-Berriasian Vaca Muerta, Carrín Curá and Picú n Leufú formations in the southern Neuquén Basin were deposited on a tidally dominated, mixed carbonate-siliciclastic ramp. Basinal, outer, middle, shallow and back ramp facies associations are recognized and a sequence stratigraphic analysis reveals that the ramp record consists of three shallowing-upwards sequences (Ti1, Ti2 and Ti3) set within a lower-order progradational cycle. A higher order of cyclicity is superimposed on to the middle (Ti2) sequence. The majority of the ramp facies belong to the transgressive and highstand systems tracts; however, at the base of Ti2, a lowstand systems tract is identified, characterized by a basal unconformity and an abrupt basinward shift of the shallow marine lithofacies. Transgressive systems tracts were characterized by slow sedimentation rates and rapid sea-level rises that affected carbonate productivity. Highstand systems tracts show the greatest carbonate productivity and an increased progradation rate on account of a reduction in accommodation space generation. Palaeogeography played a major role in the development of the depositional systems. Partial isolation from the Pacific Ocean reflecting the growth of the Andean magmatic arc and geographic restriction due to tectonic inversion in the central part of the basin resulted in a meso-macrotidal regime that produced a tidally dominated sedimentary record in the shallow and back ramp environments. Coeval anoxic conditions in the central part of the Neuquén Basin favoured distal ramp and basinal black shale deposition during episodes of relative sea-level rise.

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Organic-rich sediments were deposited in the deeper sectors of the Neuquén Basin during the latest Jurassic and the Early Cretaceous. This paper presents the results of a detailed examination of these deposits in the northern-most extension of the basin, in the Mendoza Province, and explores their wider significance for palaeo-oxygenation studies.The Tithonian—Berriasian Vaca Muerta Formation, the primary source rock for the Neuquén Basin, comprises bituminous shales and interbedded limestones deposited during a major transgression. In the Valanginian, the beginning of a regressive phase enabled the development of shallow-marine carbonates to form the base of the Chachao Formation, which eventually led to extensive biohermal carbonates of the uppermost Chachao Formation. Along the length of the narrow N-S-trending Mendoza Shelf of the Neuquén Basin both units are well exposed, permitting detailed study of the stratigraphy, sedimentology, ichnology and palaeoecology. The analysis of the Tithonian—Valanginian succession in the Salado river valley shows that carbonate production increased up-section. Faunal associations are mostly limited to poorly diverse epibenthos and pseudoplankton in the lower part of the section (Vaca Muerta Formation), with increased diversity in the lower Chachao section, including shallow and deeper infaunal bivalves. A background level of laminated shales to Chondrites bioturbation is typical of anoxic—suboxic conditions. Micritic limestones and carbonate sandstones throughout the section commonly show the development of Thalassinoides suevicus.Relative oxygenation curves based on trace fossils and body fossils were developed and compared. There was a primary substrate control on trace fossil diversity and occurrence, with a primary oxygenation signal provided by body fossil evidence. Interpretation of the palaeo-oxygenation on the basis of trace fossil taxa alone, however, would lead to inaccurate results. This study, therefore, demonstrates the importance of integrated trace and body fossil analysis in the fuller understanding of black shales.

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a b s t r a c tSedimentological, ichnological and paleontological analyses of the Early Miocene uppermost Monte Le on Formation and the lower part of the Santa Cruz Formation were carried out in Rinc on del Buque (RDB), a fossiliferous locality north of Río Coyle in Santa Cruz Province, Patagonia, Argentina. This locality is of special importance because it contains the basal contact between the Monte L eon (MLF) and the Santa Cruz (SCF) formations and because it preserves a rich fossil assemblage of marine invertebrates and marine trace fossils, and terrestrial vertebrates and plants, which has not been extensively studied. Ã 90 m-thick section of the MLF and the SCF that crops out at RDB was selected for this study. Eleven facies associations (FA) are described, which are, from base to top: subtidaleintertidal deposits with Crassotrea orbignyi and bioturbation of the Skolithos-Cruziana ichnofacies (FA1); tidal creek deposits with terrestrial fossil mammals and Ophiomorpha isp. burrows (FA2); tidal flat deposits with Glossifungites ichnofacies (FA3); deposits of tidal channels (FA4) and tidal sand flats (FA5) both with and impoverish Skolithos ichnofacies associated; marsh deposits (FA6); tidal point bar deposits recording a depauperate mixture of both the Skolithos and Cruziana ichnofacies (FA7); fluvial channel deposits (FA8); fluvial point bar deposits (FA9); floodplain deposits (FA10); and pyroclastic and volcaniclastic deposits of the floodplain where terrestrial fossil mammal remains occur (FA11).The transition of the MLFeSCF at RDB reflects a changing depositional environment from the outer part of an estuary (FA1) through the central (FA2e6) to inner part of a tide-dominated estuary (FA7). Finally a fluvial system occurs with single channels of relatively low energy and low sinuosity enclosed by a broad, low-energy floodplain dominated by partially edaphized ash-fall, sheet-flood, and overbank deposits (FA8e11). Pyroclastic and volcaniclastic materials throughout the succession must have been deposited as ash-fall distal facies in a fluvial setting and also were carried by fluvial streams and redeposited in both estuarine and fluvial settings. These materials preserve most of the analyzed terrestrial fossil mammals that characterize the Santacrucian age of the RDB's succession. Episodic sedimentation under volcanic influence, high sedimentation rates and a relatively warm and seasonal climate are inferred for the MLF and SCF section.Lateral continuity of the marker horizons at RDB serve for correlation with other coastal localities such as the lower part of the coastal SCF south of Río Coyle (~17.6e17.4 Ma) belonging to the Estancia La Costa Member of the SCF.

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