Sensitivity of the Eastern Mediterranean geomorphic system towards environmental change during the Late Holocene: a chronological perspective

Alluvial and colluvial sediment deposition provide a vital record of environmental change during the Holocene. Firm chronological control on these archives is necessary to enable us to relate sediment dynamics to human activity and climate variability. In the Eastern Mediterranean, such relationships are hard to establish due to the lack of spatially well‐distributed sediment archives with good chronological control. This scarcity is problematic with respect to regional‐scale reconstructions of the temporal variation of sediment dynamics. Here, we present a radiocarbon database (n = 178) of geomorphological activity collected from multiple distinct sediment archives within the territory of Sagalassos in south‐western Turkey. The data were grouped according to their sedimentary facies for analysis using cumulative probability distributions (CPDs) and sedimentation rate (SR) modelling. Two small‐scale colluvial valleys, where chronological information was abundant, were investigated in more detail. Results show that sedimentation chronology differs between individual, nearby cores, as it depends strongly on the local geomorphic situation. A generalizing approach combining multiple core results yields more widely valid conclusions. High sedimentation rates coincided with the initial major anthropogenic disturbance of the landscape and decreased afterwards, probably due to hillslope soil depletion. CPD and SR analysis indicates that in general colluvial sedimentation rates did not change much from 2000 BC onwards. River floodplain sedimentation, in contrast, increased markedly during the first millennium BC and during recent times, and a significant time lag in enhanced sediment deposition between the upper and lower reaches of the river valleys was observed. Copyright © 2012 John Wiley & Sons, Ltd.     

Re-equilibration of natural H2O–CO2–salt-rich fluid inclusions in quartz—Part 1: experiments in pure water at constant pressures and differential pressures at 600 °C

Re-equilibration processes of natural H₂O–CO₂–NaCl-rich fluid inclusions quartz are experimentally studied by exposing the samples to a pure H₂O external fluid at 600 °C. Experimental conditions are selected at nearly constant pressure conditions (309 MPa) between fluid inclusions and pore fluid, with only fugacity gradients in H₂O and CO₂, and at differential pressure conditions (394–398 MPa, corresponding to an internal under-pressure) in addition to similar CO₂ fugacity gradients and larger H₂O fugacity gradients. Modifications of fluid inclusion composition and density are monitored with changes in ice dissolution temperature, clathrate dissolution temperature and volume fraction of the vapour phase at room temperature. Specific modification of these parameters can be assigned to specific processes, such as preferential loss/gain of H₂O and CO₂, or changes in total volume. A combination of these parameters can clearly distinguish between modifications according to bulk diffusion or deformation processes. Bulk diffusion of CO₂ according to fugacity gradients is demonstrated at constant pressure conditions. The estimated preferential loss of H₂O is not in accordance with those gradients in both constant pressure and differential pressure experiments. The development of deformation halos in quartz around fluid inclusions that are either under-pressurized or over-pressurized promotes absorption of H₂O from the inclusions and inhibits bulk diffusion according to the applied fugacity gradients.     

MODFLOW procedure to simulate axisymmetric flow in radially heterogeneous and layered aquifer systems

A procedure is outlined to simulate axisymmetric groundwater flow in radially heterogeneous and layered aquifer systems using the unmodified version of MODFLOW. The procedure is straightforward, as it only requires correction of some of the input parameters. In contrast to other MODFLOW procedures to simulate axisymmetric flow, no restrictions are imposed on the type of flow, the discretization of radial distance, or the parameter values. Hence, the method can deal with both confined and unconfined flow, wellbore storage, and axisymmetric aquifer inhomogeneities including effects of finite-thickness skin and gravel pack. Several test cases are presented, which compare the calculated results with existing analytical solutions, the analytic element solver TTim, and the axisymmetric, finite-difference model MAxSym. It is concluded that the MODFLOW procedure is capable of simulating accurately axisymmetric flow in radially heterogeneous multi-aquifer systems.     

Low temperature behaviour of natural saline fluid inclusions in saddle dolomite (Paleozoic,NW Spain)

The origin of many dolomites is still a matter of debate because of many possible chemical and hydrological conditions of formation. Fluid inclusion studies have been applied in order to improve knowledge about paleofluids responsible for the precipitation of dolomite, and used to define temperatures and salinities. The combination of Raman Spectroscopy and microthermometry is tested here to improve the analytical method to identify the main ion species present in individual inclusions. Natural samples of saddle dolomite from the Cambrian Láncara Fm., Cantabrian Mountains (NW Spain), contain zoned crystals with two‐phase aqueous fluid inclusions (liquid‐rich). The most stable phase assemblage in these inclusions at −150 °C consists of ice, hydrohalite and an unknown salt hydrate. The latter melts between −47 and −41 °C, probably representing a eutectic temperature. Subsequently, ice melts in the range of −32.5 to −29 °C and, finally, hydrohalite melts between −9 and −3.5 °C. Salinities can be calculated in the fluid system H₂O–NaCl with addition of another salt, either CaCl₂ or MgCl₂, and result in 7.5–10.6 eq. mass% NaCl and 17.0–21.0 eq. mass% CaCl₂. Dependent on the rate of cooling runs, three different types of metastability may occur, i.e. the absence of hydrohalite, the unknown salt‐hydrate is not formed, and the nucleation of only ice. Salinity calculations from those melting temperatures differ substantially from equilibrium behaviour values. The unknown salt‐hydrate needs to be further specified by comparison to standard solutions. The method gives an opportunity to characterize the major compounds in complex fluid systems active during dolomitization, thus contributing to a better understanding of the ‘dolomite problem’.     

Characteristics of post-separation families in the Netherlands: shared residence versus resident mother arrangements

Besides the traditional post-separation residential arrangement in which the children live with the mother and have regular contact with the father, new arrangements have emerged and become more widespread in which parents strive for a more equal division of tasks. We used an explanatory mixed methods research design to enhance insight into the life course characteristics of separated parents involved in shared residence arrangements. Survey data derived from the Netherlands Kinship Panel Study (NKPS) and Divorce in the Netherlands 1998 were supplemented with information from in-depth interviews with NKPS respondents. We found that shared residence parents seem to be a typical modern category of separated parents with a specific set of characteristics. The distance between the residences of the ex-partners plays a crucial role in maintaining a shared residence arrangement. Highly educated, dual-career ex-couples, and those with high incomes are also more likely to be involved in a shared residence arrangement. Shared residence arrangements were more likely when the woman had a new partner, but less likely when the man had a new partner. Our findings on gender differences are in line with the idea that involvement in non-traditional residential arrangements is a sign of increased paternal involvement, but decreased maternal involvement, compared with the traditional arrangements.     

Hydraulic modeling of riverbank filtration systems with curved boundaries using analytic elements and series solutions

A new analytic solution approach is presented for the modeling of steady flow to pumping wells near rivers in strip aquifers; all boundaries of the river and strip aquifer may be curved. The river penetrates the aquifer only partially and has a leaky stream bed. The water level in the river may vary spatially. Flow in the aquifer below the river is semi-confined while flow in the aquifer adjacent to the river is confined or unconfined and may be subject to areal recharge. Analytic solutions are obtained through superposition of analytic elements and Fourier series. Boundary conditions are specified at collocation points along the boundaries. The number of collocation points is larger than the number of coefficients in the Fourier series and a solution is obtained in the least squares sense. The solution is analytic while boundary conditions are met approximately. Very accurate solutions are obtained when enough terms are used in the series. Several examples are presented for domains with straight and curved boundaries, including a well pumping near a meandering river with a varying water level. The area of the river bottom where water infiltrates into the aquifer is delineated and the fraction of river water in the well water is computed for several cases.     

Small‐Scale ASR Between Flow Barriers in a Saline Aquifer

Regular aquifer storage recovery, ASR, is often not feasible for small‐scale storage in brackish or saline aquifers because fresh water floats to the top of the aquifer where it is unrecoverable. Flow barriers that partially penetrate a brackish or saline aquifer prevent a stored volume of fresh water from expanding sideways, thus increasing the recovery efficiency. In this paper, the groundwater flow and mixing is studied during injection, storage, and recovery of fresh water in a brackish or saline aquifer in a flow‐tank experiment and by numerical modeling to investigate the effect of density difference, hydraulic conductivity, pumping rate, cyclic operation, and flow barrier settings. Two injection and recovery methods are investigated: constant flux and constant head. Fresh water recovery rates on the order of 65% in the first cycle climbing to as much as 90% in the following cycles were achievable for the studied configurations with constant flux whereas the recovery efficiency was somewhat lower for constant head. The spatial variation in flow velocity over the width of the storage zone influences the recovery efficiency, because it induces leakage of fresh water underneath the barriers during injection and upconing of salt water during recovery.