A major hydrobiological change in Dasht-e Arjan Wetland (SW Iran) during the late glacial-early Holocene transition revealed by subfossil chironomids

The late glacial-early Holocene transition is a key period in the Earth’s history. However, although this transition is well studied in Europe, it is not well constrained in the Middle East and palaeohydrological records with robust chronologies remain scarce from this region. Here we present an interesting hydrobiological record showing a major environmental change occurring in the Dasht-e Arjan Wetland (SW Iran, near to Persepolis) during the late glacial-early Holocene transition (ca. 11,650 years cal BP). We use subfossil chironomids (Insecta: Diptera) as a proxy for hydrological changes and to reconstruct lake-level fluctuations. The Arjan wetland was a deep lake during the Younger Dryas (YD) marked by a dominance of Chironomus plumosus/anthracinus-type, taxa adapted to anoxic conditions of deep waters. At the beginning of the Holocene a drastic decrease (more than 80% to less than 10%) of Chironomus plumosus/anthracinus-type, combined with diversification of littoral taxa such as Polypedilum nubeculosum-type, Dicrotendipes nervosus-type and Glyptotendipes pallens-type suggest a lake-level decrease and a more vegetalized aquatic environment. We compare and contrast the chironomid record of Arjan with a similar record from northwestern Iran. The palaeoclimatic significance of the record, at a local and regional scale, is subsequently discussed. The increase in northern hemisphere temperatures, inferred by geochemical data from NGRIP, at the beginning of the Holocene best explains the change from the YD highstand to early Holocene lowstand conditions in the Dasht-e Arjan wetland. However, a contribution of the melt-water inflow from small local glaciers in the catchment basin is not excluded

Early Sasanian landscape modification: New geoarchaeological evidence from the Ardashir Pond in southwest Iran (Palace of Ardashir, third century CE)

The Sasanian period (224–651 CE) marked an era of large‐scale urban projects insouthwest Asia, including Iran's semi‐arid highlands, with particular efforts to ma-nipulate water bodies. This study presents a recent interdisciplinary investigation ofa spring‐fed pond at the entrance of the Palace of Ardashir (Firuzabad plain,southwest Iran), part of a recently registered World Heritage site. Historical ac-counts suggest that the entire water system of the plain, including the pond, un-derwent a hydraulic re‐organization at the beginning of the Sasanian period, a factthat has never been investigated geoarchaeologically. A series of sediment coreswere retrieved from the pond to probe its evolution and examine the extent of itslandscape modification. The cores were sedimentologically described andradiocarbon‐dated with age–depth models established based on 57 AMS (accel-erator mass spectrometry)14C dates to understand the basin's depositional history.The results indicate that (i) Ardashir Pond has existed as part of a larger wetlandcomplex since at least 4500 years ago, (ii) it was substantially enlarged at the be-ginning of the Sasanian era, and (iii) it was abandoned at the end of the Sasanianperiod. The Ardashir Pond is one of the first geoarchaeologically investigated casestudies to demonstrate the Sasanian landscape in the framework of the“Iranshahr”sociopolitical concept

Interdisciplinary approaches to the study of resilience in the high mountains of the Southern Zagros: potential, challenges and limitations

International audienc

Investigation and Analysis of Sea Surface Temperature and Precipitation of the Southern Caspian Sea Using Wavelet Analysis

Most time series from real-world processes are stained with noise. Therefore, much attention should be paid to data noise removal techniques. In this study, we use the family of biorthogonal wavelet, high-pass, and low-pass filters, to investigate the power of the wavelet method in removing noise from time series data. Using the wavelet discrete transformation, the variability of precipitation and sea surface temperature is analyzed for a southern region of the Caspian Sea. At each stage of decomposition, the previous wave is decomposed into two waves. In this research, the SST and precipitation data are decomposed into several levels based on discrete wavelet transformation. In each level of decomposition, the previous wave is decomposed into two waves. This can be done many times and at each stage, reducing the amount of data. This method is reversible, and the original wave can be reconstructed using the decomposed values. In the study of discrete wavelet transforms, it was observed that the analysis based on wavelets leads to more accurate results. The reconstruction error in the proposed method is shown to be very small

Unraveling extreme events from deep water cores of the south Caspian Sea

International audienceSouth Caspian Sea sub-basin, as the deepest part of the Caspian Sea (CS) remained as land-locked basin even during extreme sea level fall that most part of the CS desiccated. Therefore, bottom sediments of the south CS continuously recorded many past intra-basinal and extra-basinal events. In the current research we have used four short cores (<2 m) from deep waters of the south CS (300–800 m) to unravel past extreme events based on the sedimentological and geochemical analysis. Presence of coarse grained sediment laminae in the deep basin represents frequent slope failure that transported materials from lower shelf. XRF core scanning along with Magnetic Susceptibility measurements showed multiple changes along the cores. Elements incorporating in biological activities (Ca, Sr) have sharp contrast with lithogenic elements (Zr, Ti) mainly during rapid environmental changes. The deepest core has significant changes in the basal part that covers certainly Younger Dryas or even older sediments. Material influx into the deep basin of the south CS demonstrate both basinal extreme events as turbidite and mass wasting as well as catchment basin events e.g. river avulsion that caused changes in sediment properties

Water Stress and Imperial Politics in the Southern Zagros Mountains: An Interdisciplinary Approach in Long-Term Perspective

International audienceThis paper aims to investigate episodes of water stress and the human response to them in the Southern Zagros Mountains from a long-term perspective. The integrative analysis of data from different archives allows for identification of phases of drought in the region, especially starting from the Sasanian period onwards. This investigation also shows that specific imperial politics such as that of the Sasanian Kings Kawāḏ I and Ḵosrow I helped to ensure that agricultural communities and practices were sufficiently resilient to these changes. These politics were essentially based on tax reliefs for in-need farmers and state investments on the micro-level. However, pastoral and multi-resources lifestyles remained the ultimate resilience strategies in case of severe aridification

The hazard potential of the western segment of the Makran subduction zone, northern Arabian Sea

Evaluating the hazard potential of the Makran subduction zone requires understanding the previous records of the large earthquakes and tsunamis. We address this problem by searching for earthquake and tectonic proxies along the Makran Coast and linking those observations with the available constraints on historical seismicity and the tell-tale characteristics of sea floor morphology. The earthquake of Mw 8.1 of 1945 and the consequent tsunami that originated on the eastern part of the Makran are the only historically known hazardous events in this region. The seismic status of the western part of the subduction zone outside the rupture area of the 1945 earthquake remains an enigma. The near-shore shallow stratigraphy of the central part of Makran near Chabahar shows evidence of seismically induced liquefaction that we attribute to the distant effects of the 1945 earthquake. The coastal sites further westward around Jask are remarkable for the absence of liquefaction features, at least at the shallow level. Although a negative evidence, this possibly implies that the western part of Makran Coast region may not have been impacted by near-field large earthquakes in the recent past-a fact also supported by the analysis of historical data. On the other hand, the elevated marine terraces on the western Makran and their uplift rates are indicative of comparable degree of long-term tectonic activity, at least around Chabahar. The offshore data suggest occurrences of recently active submarine slumps on the eastern part of the Makran, reflective of shaking events, owing to the great 1945 earthquake. The ocean floor morphologic features on the western segment, on the contrary, are much subdued and the prograding delta lobes on the shelf edge also remain intact. The coast on the western Makran, in general, shows indications of progradation and uplift. The various lines of evidence thus suggest that although the western segment is potentially seismogenic, large earthquakes have not occurred there in the recent past, at least during the last 600 years. The recurrence period of earthquakes may range up to 1,000 years or more, an assessment based on the age of the youngest dated coastal ridge. The long elapsed time points to the fact that the western segment may have accumulated sufficient slip to produce a major earthquake

Facing water shortages in ancient Iran: new evidence from sedimentary records of the Southern Zagros and historical insights

International audienc

Climate change: A driver of future conflicts in the Persian Gulf Region?

International audienceOngoing global change and its direct environmental impacts, in addition to securing economic transition to the post-oil era, could trigger complex socioeconomic and political crises in oil-dependent economies of the Persian Gulf Region (PGR). To evaluate the role of climate change and related policies in degrading the environment and its socioeconomic impacts in the PGR, we have used a variety of available global datasets and published data. The results show that the countries of the PGR pursue some types of socioeconomic reforms to alleviate the impacts of climate change. However, it seems that these attempts are not compatible with the environment's capacity. The main problem stems from the fact that political differences between the PGR nations prevent them from managing the Persian Gulf environment as an integrated natural system and consequently they have to limit their efforts within their borders, regardless of what happens in other parts of the system. The shift to alternative revenue sources by the countries needs socioeconomic preparedness while there are environmental obstacles, political tensions and geopolitical rivalries. Unless there is a cooperative approach to mitigate the effects of climate change, accompanied by a reorientation of PGR economies, the situation is likely to worsen rather than improve. To address the challenges of climate change, integrated regional collaborations are needed. Collective action, such as more investment in regional research and development and education, is required if the PGR is to successfully transition from a commodity-based to a knowledge-based economy

Makran continental margin sedimentation during Late Holocene

Sedimentation in the Makran active margin is governed by complex interaction of atmospheric, tectonics and hydrodynamic setting of northern flank of the Gulf of Oman. The mixed clastic carbonate sediments in tectonically and hydrodynamically active environment have complicated distribution pattern. The region is suffering from basic sedimentological data and specifically the sedimentation history of the Holocene deposits was rarely studied in Iranian coast. To deal with this deficiency, surface and core sediment samples from the Iranian continental shelf and upper slope of the Gulf of Oman have been studied using standard sedimentological techniques. The overall sediment distribution pattern demonstrates that the grain size gradually decreases from shoreline to the deeper zones. However, some medium to coarse grained sand patches can be found in deeper parts specially in the middle part of the studied area that can be related to sediment supply of ephemeral rivers discharging in to the sea in rainy seasons and/or high energy events i.e. turbidites and tsunamis during the Holocene. Several horizons of the coarse grained detrital sediments are detectable in upper slope sediment cores. The coarse grained materials are received from hinterland during flashfloods and could be accumulated due to mass wasting events. The elevated amount of organic materials in the upper slope indicates deficit of dissolved oxygen that leads to preservation of organic materials in the bottom sediments.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author