OSL Characterisation of Two Fluvial Sequences of the River Usmacinta in its Middle Catchment (SE Mexico)

The report summarizes luminescence profiling, initially using a SUERC PPSL system in Mexico, and laboratory analysis at SUERC, used to characterise the stratigraphy and interpret sedimentary processes in terrace deposits of the Usumacinta River, SE Mexico. This was then followed, by quantitative quartz OSL SAR dating of five sediment samples, aimed at defining the chronologicalframework of two sedimentary sequences, USU13-1 and USU13-2. In the wider region, the middle catchment of the Usumacinta River, contains numerous archaeological sites dating to the Maya Classic Period, including Bonampak, Yaxchilan and Piedras Negras. The broader aim of the investigation is to assess whether the two fluvial sequences contain a proxy record of environmental change through the archaeological period of interest. Initial luminescence profiling revealed that the stratigraphy in each profile was complex, reflecting multiple cycles of deposition, with signal maxima, followed by tails to lower intensities, possibly indicating deposition during extreme flood events, interleaved with periods of slower sedimentation, and potentially better luminescence resetting. Laboratory profiling reproduced the apparent maxima/trends in the field profiling dataset, confirming that both sections record complex depositional histories. Furthermore, the variations in stored dose estimates, and luminescence sensitivities with depth, confirm that the sections do not record simple age-depth progressions. Quantitative quartz OSL SAR dating was undertaken on five sediment samples. Given the information obtained from the field- and laboratory-profiles it is not surprising that the equivalent dose distributions for each sample showed considerable scatter, particularly so for the second section, USU13-2. Nevertheless, throughstatistical analysis, individual quartz OSL SAR ages were obtained for each sample. Individual dates fall into the Mayan Post-Classical Period to early modern Period, with statistical combinations pointing to a late 15th century accumulation of USU13-1, and the 18th century accumulation of the sediment within USU13-2. Interestingly, the three samples from section USU13-2, all show some aliquots which tail to higher equivalent doses; furthermore, in each sample, the mean value determined for this component is similar, suggesting that the sediment sampled in USU13-2, may be sourced from a 15th century or older accumulation upstream

Birth, life and death of the Pannonian Lake

The Miocene-Pliocene Pannonian Lake formed in an extensional basin system behind the compressional arc of the Carpathians. Its size and depth were comparable to those of the Caspian Sea. Subsidence began in Middle Miocene times, forming deep, pelagic basins, separated by reef-bearing ridges. Clastic influx filled the marginal basins during Middle Miocene time. Prograding deltas dissected the lake and completed the infilling of the basin system by the end of the Pliocene. Basin plain, prodelta, delta front, delta plain, beach, fluviatile, and marsh environments can be recognized. Terminal Miocene uplift of the Carpathians isolated the Pannonian region from the rest of Paratethys. The subsequent decrease of salinity resulted in the evolution of an endemic, freshwater mollusc fauna. Rich nutrient influx from rivers supported high organic productivity (dinoflagellates, diatoms, nannoplankton, foraminifers, ostracods, etc.), yielding organic-rich sediments. Preservation of organic matter was helped by a stratified water column and oxygen deficient bottom conditions. Deep burial, continuing subsidence, and high geothermal flux due to an extremely thin crust, led to the formation of commercially exploitable oil and gas accumulations. Shallow lacustrine zones of basin margins provided suitable environments for a rich Congeria-Melanopsis mollusc fauna. Wave action on beaches produced commercially exploitable pure quartz sand deposits. Taxodium and Alnus forests flourished around the lake producing enormous lignite deposits. Besides a rich land snail and mammal fauna, prehominids lived in the forests. There was a warm, temperate climate, with probably frostfree winters. Basaltic volcanoes overlooked the landscape, and maars hosted minor lakes with rich algal flora forming oil shale. The catchment area included most of the Carpathians and parts of the Alps and Dinarides. The positive water balance resulted in a supposed overflow in the southern margin, supplying exotic fauna to the South Carpathian and Dacian basins of the Eastern Paratethys. The Pannonian Lake was completely filled by the end of Pliocene. Recent lakes in the Carpathian Basin are not descendants of it

Book notices and Book reviews

Book notices and Book reviews from Volume 1, Number 2, 1967 of Earth Science Journal

Integrated stratigraphy of the Upper Hauterivian to Lower Barremian Agua de la Mula Member of the Agrio Formation, Neuquén Basin, Argentina

The Upper Hauterivian to Lower Barremian Agua de la Mula Member of the Agrio Formation (Neuquén Basin, Argentina) was studied applying an integrated stratigraphic approach and facies analysis. The ammonite biostratigraphy of the member has been improved based on bed-by-bed collecting. The already defined biozones (S. riccardii, C. schlagintweiti, C. diamantensis and P.groeberi) were recognized, precisely related to the succession, and further refinement was proposed. Sequences of different order are built by stacked starvation/dilution (S/D) sequences, regarded here as sixth order sequences with only two components that can be unequivocally distinguished: the lower starvation hemisequence and the upper dilution hemisequence. Pro- and retrogradational stacking pattern of S/D sequences define supra-ordinate sequences. The sequence-stratigraphic analysis resulted in the subdivision of the member into four main depositional sequences (DSAM-1 to -4) and several subordinate sequences. Previously published sequence stratigraphic charts of the Neuquén Basin did not relate sedimentary sequences to biozones, and are hence not comparable to the scheme presented here and other charts. Our study shows a good agreement with the sequence-chronostratigraphic scheme of European basins, thus arguing in favour of a predominantly eustatic control on sequence development during the Late Hauterivian to Early Barremian. A latest Early Barremian age is proposed for the almost ammonite-barren upper part of the Agrio Formation, based on correlations of sequence boundaries.Fil: Archuby, Fernando. GeoZentrum Nordbayern; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Wilmsen, Markus. Museum für Mineralogie und Geologie; AlemaniaFil: Leanza, Hector Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; Argentin

Optically-stimulated luminescence profiling and dating of historic agricultural terraces in Catalonia (Spain)

Dating agricultural terraces is a notoriously difficult problem for archaeologists. The frequent occurrence of residual material in terrace soils and the potential for post-depositional disturbance mean that conventional artefactual and lab-based dating methods often provide unreliable dates. In this paper we present a new technique using luminescence field profiling coupled with OSL dating to produce complete (relative) sequences of dates for sedimentary stratigraphies associated with agricultural terraces and earthworks. The method is demonstrated through a series of case-studies in western Catalonia, Spain, in which we reconstruct the formation sequence of earthwork features from the Middle Ages through to the present day. OSL profiling at the time of archaeological survey and excavation permitted spatially and temporally resolved sediment ‘chronologies’ to be generated, and provides the means to interpret the environmental and cultural archives contained in each. The case-studies presented here show that luminescence approaches are a valuable tool to reconstruct landscape histories

Eastern Taranaki Basin field guide.

Linking the onshore and offshore parts of Eastern Taranaki Basin: Insights to stratigraphic architecture, sedimentary facies, sequence stratigraphy, paleogeography and hydrocarbon exploration from the on land record

The rock components and structures of Archean greenstone belts: An overview

Knowledge of the character and evolution of the Earth's early crust is derived from the studies of the rocks and structures in Archean greenstone belts. Ability to resolve the petrologic, sedimentological and structural histories of greenstone belts, however, hinges first on an ability to apply the concepts and procedures of classical stratigraphy. Unfortunately, early Precambrian greenstone terrains present particular problems to stratigraphic analysis. Many current controversies of greenstone belt petrogenesis, sedimentology, tectonics and evolution arise more from an inability to develop a clear stratigraphic picture of the belts than from ambiguities in interpretation. Four particular stratigraphic problems that afflict studies of Archean greenstone belts are considered: determination of facing directions, correlation of lithologic units, identification of primary lithologies and discrimination of stratigraphic versus structural contacts