Correlation of the fluvial magnetic susceptibility (MS) record of borehole Devavanya‐1 in the Körös Basin (eastern Hungary) with Chinese aeolian MS records (Jingbian, Lingtai) and the marine δ18O record from the Equatorial Pacific (V28‐239) is established here based on cross‐correlations and singular spectral analysis. A basin‐scale well‐to‐well correlation based on magnetic susceptibility records was also performed involving unpublished cores. To refine the age model, a Monte Carlo simulation was conducted using the Chinese Jingbian section as a tuning target. Spectral analysis of the tuned record revealed c. 400, c. 100 and c. 41 ka cycles over the 2.5 million years of the Quaternary fluvial succession. To ensure a complementary palaeoclimate proxy, the full width at half maximum of smectites was measured as a facies‐independent indicator of weathering intensity. This investigation was carried out on a subset of samples involved in MS measurements representing a c. 400 ka time interval across the top of the Olduvai subchron. A phase‐shift between MS and weathering intensity recorded in the clay mineralogy indicates different response times of the considered proxies. The fluvial MS record is determined by the climatic control on delivery and preservation of magnetic minerals, mainly of magnetite. Under cold‐and‐dry climate these minerals were released owing to frost shattering in the adjacent hinterlands and were transported to alluvial plains in the early postglacial periods thanks to the increasing discharge of rivers. With further warming the weathering‐sensitive magnetic minerals soon disappeared from the soils of the catchment area and thus from the fluvial load. As a result, in fluvial successions early postglacial warmings are expressed by the occurrences of MS maxima (magnetic episodes), while the palaeotemperature maximum and the subsequent cooling remain concealed within the tract of low MS values. The early postglacial magnetic episodes may serve as ideal stratigraphical markers in regional and global correlations.

The laboratory determination of scale inhibitor (SI) performance under field specific conditions using dynamic or static scale inhibitor tests provides an important method for determining minimum inhibitor concentrations (MIC's) for the inhibition of scale growth. This paper will discuss the ability of small amounts of ferrous iron to dramatically reduce the ability of SI's to inhibit calcium carbonate scale formation under dynamic laboratory test conditions. It has been previously reported that the presence of ferrous ions has an inhibiting effect on calcium carbonate formation under dynamic test conditions, which was confirmed for the brine systems used in this study. However, despite the somewhat milder scaling regime in the presence of ferrous ions, addition of Fe2+ ions to test brines caused the observed MIC's of typical scale inhibitor chemicals to increase more than one hundred fold when tested against calcium carbonate scale. A much less dramatic reduction in SI performance in the presence of ferrous ions was observed for barium sulfate scale formation under dynamic test conditions. Such interference in inhibitor performance can have major implications for the field application of scale inhibitor chemicals, leading to unexpected decline in production. The presence of ferrous ions has been shown to adversely affect scale inhibition of a number of different classes of SI chemicals, including poly(vinylsulphonate) (PVS) which has previously been reported as being iron-tolerant. This paper will describe the results of laboratory studies into this phenomenon, in which the nature and scope of the interference were investigated. Introduction Inhibitor performance in terms of the minimum inhibitor concentration (MIC) or the threshold concentration required to prevent scale is one of the most important aspects for scale control additives, equalled only by the challenge of effective placement and deployment in today's ever more complex production environments. The laboratory test protocols adopted throughout the industry are very similar and are based upon static "bulk" inhibition performance tests and dynamic "tube blocking" inhibitor performance tests. The importance of appropriate laboratory test procedures has recently been discussed in detail.[1] The conventional static "bulk" or "jar" test procedures commonly adopted are related to that described in the NACE standards TM 0197–97[2] and TM 0374–2001.[3] Such tests have been described in many previous papers for both examination of the factors controlling inhibitor performance and for selecting scale inhibitor products prior to field applications. These tests are used routinely throughout the industry for scale inhibitor selection and optimisation studies.[1] In addition to static "jar" tests, dynamic "tube blocking" performance tests are also routinely used for scale inhibitor selection in oilfield environments. Dynamic tests complement static tests by allowing different facets of scale inhibitor activity to be examined. For example, dynamic tests examine activity under much shorter residence times than static tests, and so can be used to highlight differences between nucleation and crystal growth inhibition effects. Dynamic tests also allow for the impact of scale nucleation and growth on the walls of the micro-bore tubing to be assessed under laminar flow conditions. There are a number of benefits associated with dynamic performance tests, which have been described in a number of previous publications as follows[1]:Dynamic laminar flow system, as in oilfield productionExamines growth and blockage of microbore metal coilsSystems can be examined under pressure. This allows for routine testing under;higher temperature conditions (> 100°C),in the presence of bicarbonate ions without loss of pH control Finally, and of more importance for this study, the sealed nature of the dynamic flow tests means that:Examination of systems in the presence of dissolved iron can be more readily achievable than in static tests, provided that feed brines are adjusted accordingly to minimize potential oxidation of Fe(II) - > Fe(III).[4]

Quaternary fluvial succession of the Jászság Basin (Hungary) was investigated, challenging the stratigraphical potential of ‘early postglacial fluvial magnetic susceptibility episodes' recognized earlier in the Körös Basin. Low field magnetic susceptibility (MS) was measured in four boreholes from the basin centre and margins, representing channel and flood‐plain environments. Statistical distributions of MS data contain significant sets of outliers, regardless of facies conditions. The downhole distribution of these outliers produces magnetic susceptibility cycles. Supported by magnetic susceptibility cycles, high‐resolution facies correlations were performed reflecting a steady palaeohydrographical situation in the area, with a trunk river to the southeast and tributaries to the northwest. SEM‐EDX data revealed that ferromagnetic grains are responsible for the outlying MS values. The heterogeneous association of magnetite indicates a catchment area with volcanic and metamorphic rocks, while the group of small (<5 μm) magnetite octahedrons originated from nearby rhyolitic tuff formations. Magnetic grains were transported along channel belts, while small (<2 μm) magnetic particles were floated onto flood‐plains attached to clays. Climatic control is indicated by peaks at ~100 ka frequency in spectra of MS records and was also detected in palaeosol development and in flood frequency using the spectra of measured colour (~100 ka) and logged resistivity (~100 ka, ~41 ka), respectively. The climate‐dependent MS signal traceable far into the basin in both channel and flood‐plain environments can be summoned when the Quaternary fluvial succession of the Pannonian Basin is investigated, assuming some sources of magnetite in the catchment areas. According to the concept of ‘fluvial magnetic susceptibility episodes’, the early postglacial escape and spreading of the magnetite fraction control the MS signal that can support mapping of the unconformable Quaternary base and building of high‐resolution models of aquifers.

No abstract

Community level ecology is considered to support significantly the recognition of the ecological status of plant taxa and the identification of plant ecogroups, thus it generally