Northern Alborz Research Articles

Structure and kinematics of active faulting in the northern domain of Western and Central Alborz, Iran and interpretation in terms of tectonic evolution of the region

Field evidence, seismicity, and geodetic data are combined to define the tectonic evolution along the northern domain of the Western and Central Alborz ranges, which have experienced significant earthquakes. One of our main focuses is to present the geometric-kinematic characteristics of active fault planes in the North Alborz fault zone and its subsidiary faults as a basis for seismic hazard assessment. To evaluate the seismotectonics in the region, three active segments of the seismic zone are identified. These segments primarily exhibit reverse mechanisms and left-lateral strike-slip components and act as the boundaries of neotectonic stress domains around the transition zone between Alborz and the South Caspian Basin. The spatial distribution of the strike-slip and dip-slip faulting over the Western and Central Alborz range supports our understanding of the geodynamic processes of the region. Our map of local active faults reveals five main systems with N–S, NE–SW, ENE–WSW, E–W, and NW–SE directions. Field studies indicate that strike-slip movements predominate and are consistent with a ∼WNW-ESE-oriented left-lateral wrench system. Pure left-lateral strike-slip faults trending E-W, extensional faults trending NE–SW, and compressional faults trending NW-SE are identified. Regional field investigations reveal spatial variations in the fault zone width of the northern domain of the Western and Central Alborz. The findings demonstrate that fault zone structures and their spatial distribution along the width of the area are strongly affected by the strain partitioning process in the transpressional zone. A spectacular well-exposed transpressional zone from the Western and Central Alborz region is described in detail, where outer domains are faults with a dominant reverse mechanism, and the inner domain is a wrench zone that includes faults with a dominant strike-slip mechanism. The seismic activity in the Northern Alborz region is mainly concentrated along the North Alborz fault zone and its subsidiary fault planes, of which some are identified for the first time in this research. Significant seismic events have occurred at locations where these newly identified fault planes interact. The maximum values of the geodetic strain axes in Western and Central Alborz are consistent with the area of high seismicity.

A SYNTHESIS OF THE GEOLOGY AND PETROLEUM GEOLOGY OF THE IRANIAN PORTION OF THE SOUTH CASPIAN BASIN AND SURROUNDING AREAS

The South Caspian Basin, the northern Alborz Mountains, the Gorgan plain and the Moghan plain constitute the northernmost and youngest petroleum system in Iran. This region was part of the Paratethys realm from Oligocene to Pliocene time. The Oligocene – Miocene Maikop/Diatom Total Petroleum System of the South Caspian Basin produces major volumes of hydrocarbons in Azerbaijan and Turkmenistan, and the Iranian sector of the basin has consequently undergone exploration due to its generally similar geology. The 20 km thick, dominantly Cenozoic sedimentary cover in the basin is reduced to less than 3 km in the northern foothills of the Alborz Mountains, and scattered surface oil seepages in the latter region are believed to be generated by Cretaceous and Miocene source rocks. In the Moghan plain to the southwest of the South Caspian Basin, anticlinal folds of Oligo‐Miocene Zivar Formation sandstones may be prospective for hydrocarbon exploration. Mud volcanoes in the Gorgan plain and in adjacent offshore regions at the SE margin of the South Caspian Basin are associated with hydrocarbon seepages, and appear to be sourced by Cretaceous and Cenozoic shales and mudstones. Major structural features in the southern part of the South Caspian Basin include Cenozoic mud diapirs, folds and gravity structures.

Changeability of runoff and soil loss from inclined mid-sized plots under simulated upward wind-driven rain

The present study investigated the interaction of wind and rain (WDR) on splash and interril erosions under laboratory conditions. The corresponding experiments were carried out with rainfall intensity of 50 mm h−1 with a duration of 30 min under no-wind control conditions and two wind velocities viz., 3 and 6 m s−1 at a slope of 12%. The study was conducted on sandy-loam soil from summer rangelands of the Northern Alborz Mountain in Iran. The soil collected was transported to the Rainfall and Erosion Simulation Laboratory. The prepared 6 × 1 m-plots were concurrent with the simulation of the WDR. Moreover, three splash cups were used to measure splash erosion, and each cup was placed on the soil surface at distances of 1.5, 3.0, and 4.5 m from the plot outlet. The results displayed the significant effects of wind (P < 0.01) on runoff generation and soil erosion components. Therefore, the mean runoff and runoff coefficient decreased while increasing wind velocity increased sediment concentration and soil loss. The mean runoff volume and coefficient were 103.48, 94.62, and 88.82 L and 94.43, 87.23, and 81.62 % at wind velocities of 0, 3, and 6 m s−1, respectively. In addition, the mean soil loss and sediment concentration were 414.94, 1057.47, and 1375.48 g; and 31.35, 156.31, and 303.75 g L−1; at 0, 3, and 6 m s−1 wind velocities, respectively. Besides, the mean net splash increased significantly with increasing wind velocity, from 9.58, 14.93, and 18.63 g, respectively, as wind velocity changed from 0 to 3 and then 6 m s−1. It has been proven that WDR soil erosion was higher than no-wind rain. This research could increase soil managers' awareness of solution strategies.

A Study on Properties of Deoxynivalenol (DON) Production in Culture Medium by Aspergillus Spp. Isolates from Northern Iran.

The increased fungi contaminations and related damages cause disease through production of toxins in animals and thus in humans. Since they are not easily distinguishable, then it is crucial to study their characteristics. Aspergillus are among the most important toxigenic fungi that are found abundantly in northern Iran habitat which is one of most important habitat of Iran and is the main source for many feed and food stuffs in the state. Hence, we aimed to study on properties of deoxynivalenol (DON) production in culture medium by 24 Aspergillus spp. isolates from northern Iran. Samples were collected from Northern Alborz and Southern Caspian Sea agricultural plants cultivation areas and processing centers. Samples were then isolated and identified based on CBS environmental sampling rules and ICPA diagnostic standards. They were cultured to stimulate the toxin production until the targeted toxin to be measured at culturing substrate and fungi biomass. Afterward, they were exposed to extraction and existing DON size were measured by ELISA technique Our results indicated that in addition to Fusarium, genus Aspergillus has a potent ability to produce DON toxin or alike molecules. However, validation of this issue needs further studies, in particular, by using advanced biochemical or genomic molecular techniques.

ANALYSIS OF PHYSICAL INDICES IN EARTHQUAKE RESILIENCE OF BABOL NEIGHBORHOODS, IRAN

In recent years, one of the most important goals of urban managers has been the planning for resilience to natural disasters, especially earthquakes. Babol, as the second most populous city of Mazandaran province in northern Iran, is exposed to earthquakes due to its proximity to two active faults, the Caspian Sea and northern Alborz. The purpose of this study was to evaluate the effective physical indicators in the resilience rate of 22 neighborhoods of Babol. The research method is descriptive-analytical and applied-developmental. Accordingly, 48 effective indicators in the physical dimension were extracted and evaluated for their suitability through KMO test in consultation with experts and professors in urban planning, crisis management and earthquake. Then, the selected indices were reduced to four factors by factor analysis, which accounted for 61.9% of the variance. Among the four factors, the first factor alone accounted for 24.8% of the variance, which is the most influential factor in the study, and the fourth factor with 10.3% of the variance has the least effect. Cluster analysis was used for homogeneous classification of the neighborhoods and Babol's 22 neighborhoods were classified into 8 homogeneous groups. The results of clustering method show that about 40.9% of neighborhoods are evaluated as very poor, poor and relatively poor and in undesirable conditions in general. Also, about 18.2% of the neighborhoods are in the medium level and about 40.2% of the neighborhoods are evaluated as good, very good, excellent and very excellent levels in terms of physical resilience.

Analysis of channel bank erosion rate using exposed roots of trees: a case study of lavij stream, northern Alborz Mountains, Iran

Powerful alluvial rivers in the northern Alborz mountain ranges erode river banks due to having high slopes. Most of these rivers flow in forest areas. In this research, the rate of the river bank erosion was examined using the exposed roots of the trees. For this purpose, 8 reaches of Lavij Stream were investigated. To determine the first year of root exposure, two sets of macroscopic and microscopic indicators were utilized. Accordingly, the rate of the stream bank erosion was estimated. The results were analyzed by using statistical test, which showed insignificant differences between the two groups of indicators. Due to its more abundance (frequency) on the margins and easy detection of its root through the exposure (macroscopic and microscopic) indicators, Alnus glutinosa (black alder) species could be more easily and accurately analyzed as compared with any other tree species in the region. The mean erosion rate of the riverbank using the extruded roots was estimated to be 0.08 m/yr. The hydrological analyses of flood flows showed that 95% of Lavij Stream bank erosion was caused by the river bank full discharges with a return period of 1–3 years.

Benthic Foraminifera Across the Cretaceous/Paleogene Boundary in the Eastern Tethys (Northern Alborz, Galanderud Section): Extinction Pattern and Paleoenvironmental Reconstruction

AbstractExtinction patterns, paleobathymetric inferences, and paleoenvironmental changes based on benthic foraminifera were investigated across the Cretaceous/Paleogene (K/Pg) boundary at the Galanderud section (Northern Alborz, Iran), which contains one of the most continuous and expanded K/Pg transitions in the eastern Tethys. On the basis of benthic foraminiferal taxa abundance and distribution, an outer neritic to uppermost bathyal paleo-depositional setting is inferred. In addition, benthic foraminiferal assemblages and planktic/benthic ratios do not indicate any major change in relative sea level during latest Maastrichtian-early Danian time.Changes in benthic foraminiferal assemblages, morphotypes, diversity, heterogeneity, and benthic foraminiferal oxygen index, coupled with statistical analyses, define three intervals. In the first interval (uppermost Maastrichtian Plummerita hantkeninoides Zone), benthic foraminiferal assemblages are moderately to well preserved and highly diverse, with a combination of epibenthic and endobenthic taxa indicating stable, mesotrophic to weakly eutrophic, normal marine conditions. A major change in benthic foraminiferal assemblages at the K/Pg boundary defines a second interval (basal Danian Guembelitria cretacea and lower part of Parvularugoglobigerina eugubina Zones) that is marked by a decrease in the endobenthic morphogroups as well as a decrease in diversity, heterogeneity, genus and species richness. This second interval denotes highly oligotrophic conditions and a collapse in productivity and food availability due to the extinction of some primary producers, with the exception of the three chalk beds representing short-lived blooms of calcareous dinoflagellates. Benthic foraminifera do not show significant extinction at the end of the Cretaceous at this section with only about an 8% loss of species. Additionally, the abundance of some opportunistic species, including Cibicidoides pseudoacutus and Tappanina selmensis, may reflect instability in the benthic foraminiferal assemblages. The third interval (middle-upper part of the Pv. eugubina Zone) is characterized by the dominance of epibenthic morphogroups (up to 70% of the assemblages) with a partial recovery of endobenthic groups. The characteristics of the benthic foraminiferal assemblages indicate that the flux of food to the benthos had not fully recovered during the early Danian.

Cretaceous magmatic evolution in the Deylaman igneous complex, Alborz zone, Iran: change from extensional to compressional regime

The Deylaman igneous complex, as a part of the Late Cretaceous rock unit that lies behind the Paleogene Alborz magmatic arc, in the northern Alborz zone, is composed of basaltic sheet lavas alternating with the pelagic calcareous sediments, basaltic pillow lavas, felsic lavas and gabbroic-monzodioritic intrusions. The pelagic calcareous deposits contain microfossils representing the Santonian–Maastrichtian ages. Furthermore, petrographic textures such as the hyalomicrolitic texture and swallow-tail plagioclase crystals in the pillow lavas, and also segregation vesicles in the basaltic sheet lavas, imply high external (hydrostatic) pressures as the magma was extruded in a deep-water environment. The rock samples show both compositional bimodality and characteristic trends in the variation diagrams. Also, some geochemical characteristics imply that the basaltic lavas originated from the partial melting of an undepleted deep mantle source containing spinel lherzolite: the enrichment patterns of LREE/HREE ratios of the samples [(La/Yb)n = 3.93–4.16 for basaltic lavas and 10.92 for felsic lavas] lying between those characteristic of OIBs [(La/Yb)n = 12.92] and EMORBs [(La/Yb)n = 1.91]; similarities between the patterns of multi-element spider-diagrams; LILE bulges in the basaltic samples compared with those of OIBs. Moreover, the samples show influence from two geotectonic environments: supra-subduction zone (SSZ) settings and plume-type within-plate magmas. Therefore, because of the deep submarine environment inferred for the effusive volcanic eruptions in Santonian–Maastrichtian time, it seems that the Deylaman igneous complex evolved through two stages: first, a tensional regime in a supra-subduction zone (farther from the Mesozoic magmatic arc) and formation of an embryonic rift-related oceanic basin in the Late Jurassic–Early Cretaceous; secondly, a compressive regime in the Late Cretaceous–Early Paleocene and inland migration of the magmatic arc. Consequently, the Cretaceous magmatism can be interpreted as a prelude to the Eocene magmatic flare-up in the magmatic arcs of Iran.

Block rotation induced by the change from the collision to subduction: Implications for active deformations within the areas surrounding South Caspian Basin

Northern of Iran is experiencing a complex deformation due to the northward convergence of Arabian plate since late Cenozoic. The majority of this complexity is due to the presence of a rigid, old, thickened oceanic crust of the South Caspian Basin (SCB). This rigid block, trapping between Eurasia and Central Iran, makes an inhomogeneous body in the context of deforming zone composed by Alborz, Talesh, Apsheron-Balkhan, Caucasus, and Kopeh Dagh located in south, west, northwest, north, and east of the SCB, respectively. Among them, the formation and evolution of the Alborz orocline are under debates. The presence of sinistral strike-slip faults with normal separation initially understood by NW motion of northern Alborz inferred by GPS measurements raised long debates. In the latest proposition, it is assumed that the SCB is rotating clockwise. This study, however, shows that the model of SCB's rotation and/or NW-ward motion of SCB is not kinematically consistent. Therefore, it aims at constraining the Alborz, northern central Iran, and NW Iran, as a sliver block, are rotating around the SCB. The block rotation is facilitated by geo-sutures inherited since Paleozoic. Therefore, this article specifically pays attention to the active extensional tectonic regime as a signal for the area that is under rotational movement. The block rotation induced by the change from the collision (in Kopeh Dagh) to subduction (SCB and Kura Basin beneath Alborz, Talesh, Apsheron-Balkhan, and Great Caucasus, respectively), and consequently the reactivation of ancient geo-sutures in northern Iran led to a rapid rotation of microcontinents. This assumption may account for the ongoing deformational pattern in Alborz and NW Iran. The disharmonic Arabian plate convergence and SCB's retreating induce forces by the block rotation and cause episodic tectonic activities that are responsible for current tectonic complexity in the north of Iran. If the climax of the collision was ~5 Ma, then the block rotation and related deformation are younger events with respect to the collision and subduction.

Mississippian lithofacies and foraminiferal biozonation of the Alborz Mountains, Iran: Implications for regional geology

The Mississippian rocks at 5 sections, Kalariz, Peyghambaran, Jaban, Naserabad, and Dozdehban, have been measured and sampled in a SE–NW direction across the Alborz Mountains. Foraminiferal zones recognized in those sections, as well as a revision of other foraminiferal assemblage previously published from the Alborz Mountains, allow to recognize 12 biozones: 5 in the Tournaisian: Unilocular (MFZ1–MFZ2? interval), Septabrunsiina krainica (MFZ3–MFZ5 interval), Eotextularia diversa (MFZ6), Darjella monilis (MFZ7), and primitive Eoparastaffella (MFZ8); 5 Viséan biozones: Eoparastaffella simplex (MFZ9), primitive archaediscids (MFZ10), Uralodiscus rotundus (MFZ11), Pojarkovella–Koskinotextularia (MFZ12), Neoarchaediscus (Upper Mikhailovian), Howchinia gibba–Archaediscus/Paraarchaediscus at angulatus‐tenuis stage–Neoarchaediscus akchimensis (Venevian substage); and 2 Serpukhovian biozones: Biseriella parva–Climacammina (Tarusian–Steshevian substages) and Turrispiroides multivolutus–Brenckleina–Eostaffellina protvae (Protvian substage) for the Mississippian rocks of Alborz. Analysis of foraminiferal assemblages indicates a noticeable age difference of the Mississippian rocks between the northern and southern flanks of Alborz. Accordingly, south‐eastern and east‐central Alborz (Kalariz, Peyghambaran, and Jaban sections) display complete Tournaisian deposits (MFZ1–MFZ8), whereas northern Alborz contains the strata dated from Late Tournaisian to Late Serpukhovian (MFZ8–MFZ16). The sedimentological studies also reveal sharp facies variations following the mentioned age variation. Previously, the age variations of these rocks were attributed to various events, such as the Mississippian glaciation phases. However, the age, facies, and thickness variations of lithostratigraphic units in the Alborz are not specific to the Mississippian and are reported during the entire Palaeozoic and even Mesozoic and Cenozoic. They can rather be attributed to the inherited basement and syn‐sedimentary E–W‐trending faults.

The Cretaceous-Paleogene transition at Galanderud (northern Alborz, Iran): A multidisciplinary approach

We investigated the Cretaceous-Paleogene (K/Pg) transition at the Galanderud section, northern Alborz (Iran) to identify the pattern of mass extinction of planktic foraminifera and to unravel the associated paleoenvironmental changes in a little-studied area of the eastern Tethys. We applied a high-resolution quantitative and multidisciplinary study based upon benthic and planktic foraminiferal assemblages, clay mineralogy, rock magnetic properties, stable isotopes, and geochemistry. In this section, the K/Pg boundary is marked by an abrupt change in lithology from marl to a clay boundary layer, a marked decrease in magnetic susceptibility, a negative 2.2‰ δ13C excursion, and a peak in iridium. In the uppermost Maastrichtian, foraminifera are well preserved and diversified suggesting a stable, mesotrophic environment. By contrast, the K/Pg boundary and basal Danian is marked by high values of epifaunal benthic morphogroups, low planktic diversity, and high percentages of opportunistic species (Guembelitria cretacea and Cervisiella operculata) suggesting highly stressed and variable conditions, partly due to the dramatic collapse of calcareous primary producers. Benthic foraminiferal assemblages indicate outer neritic-uppermost bathyal depths with slight bathymetric variations. The most peculiar and unique aspect of the Galanderud section is the occurrence of the three thin chalk layers interbedded within clays above the K/Pg boundary, each marked by positive shifts in δ13C and δ18O values, and consisting of >80% carbonate. We propose that the chalk/clay deposits in the basal Danian reflect changes in seawater chemistry and dynamic changes in circulation (upwelling) alternating with episodes of enhanced weathering and runoff. This section on the northern margin of eastern Tethys provides new clues about the pattern of the K/Pg mass extinction and the paleoenvironmental changes occurring during the biotic recovery phase.

Spatial Variation of Soil Seed Bank under Cushion Plants in a Subalpine Degraded Grassland

AbstractCushion plants can affect wind speed and sediment movement patterns that probably modify the water and sediment redistribution along slopes and increase the accumulation of seeds under and around their canopies. This study was carried out to assess the spatial variability of soil seed bank (SSB) and seed bank composition around cushion plants to estimate the SSB potential for restoration of degraded area. Twenty cushions of Onobrychis cornuta were selected in a mountainous rangelands in northern Alborz in Iran, measuring density, richness and composition of SSB at four locations of each cushion (upslope edge, downslope edge, centre and outside). SSB composition and density were determined by seedling emergence method. The results showed that the locations of cushions had significant effect on density and richness of the SSBs. The highest SSB density and richness were observed in the centre and upslope edge of the cushions, while there was no significant differences of density and richness between downslope edge and outside (bare grassland soil) of the cushions. In addition, the results showed that seed bank composition was highly correlated between the four locations in the same cushion. We concluded that cushion plants can act as seed traps specially trapping seeds dispersed by barochory and hydrochory and therefore play an important role in conservation and recovery of degraded areas. Copyright © 2017 John Wiley &amp; Sons, Ltd.

New data on the Late Viséan–Late Serpukhovian foraminifers of northern Alborz, Iran (biostratigraphic implications)

The Upper Viséan–Upper Serpukhovian deposits of northern Alborz (Iran) consist of thin-bedded, fine sandstone and siltstone, marly and ooidal limestone and marly shale. Rich and diverse foraminiferal assemblages have been analyzed in two sections (Dozdehban and Naserabad). Five biozones and most foraminifers are first described from Upper Viséan–Upper Serpukhovian deposits of Iran. The Late Viséan of the area is subdivided into a Neoarchaediscus Zone and a Howchinia gibba–Archaediscus/Paraarchaediscus at angulatus-tenuis stage-Neoarchaediscus akchimensis Zone correlated to the Upper Mikhailovian–Venevian and Early to Late Brigantian substages of the Russian Platform and Western Europe. The Early Serpukhovian corresponds to the Biseriella parva–Climacammina Zone, and the Late Serpukhovian includes the Turrispiroides multivolutus–Brenckleina–Eostaffellina protvae zone that correlate to the Tarusian–Steshevian and Protvian substages of the Russian Platform, respectively. Furthermore, the upper beds in the Naserabad section contain the Plectostaffella–Globivalvulina kamensis? Zone, which is dated as Zapaltyubian?, lastest Serpukhovian.

The Effect of the Habitat Type on Soil and Plant Diversity Properties in Natural Ecosystems in the Northern Alborz (Case Study: Vaz Watershed)

The Effect of the Habitat Type on Soil and Plant Diversity Properties in Natural Ecosystems in the Northern Alborz (Case Study: Vaz Watershed)

Agro-morphological and phytochemical diversity of various Iranian fennel landraces

Fennel is used for various purposes in medical, cosmetic and food industries and Iran is one of its main producers. In this study agro-morphological and phytochemical diversities of Iranian fennel landraces were assessed. According to phenological properties, Iranian fennels were classified as early, medium and late maturity. Based on two years data, late and medium maturity fennels had the higher amounts of vegetative and reproductive traits. In term of seed yield, medium maturity fennels had a better performance, and in term of essential oil content medium and late maturity fennels had the highest values. With considering essential oil yield the highest values were related to medium and late maturity landraces. According to GCMS analysis, in essential oil of the studied Iranian fennels, trans anethole content ranges from 1.24 to 88.45, methyl chavicole from 0.22 to 59.1, fenchone from 1.22 to 14.74 and limonene from 5.5 to 15.71%. Trans anethole chemotype landraces were belonged to arid areas of eastern Zagros and southern Alborz; methyl chavicole chemotype landraces to humid areas of western Zagros and northern Alborz; fenchone chemotype landraces to late maturity landraces from humid area of northern Alborz; and he highest limonene contents to landraces from areas with mediocre altitude in north of Iran. Based on path analysis, as morphological markers to improve seed yield, negative selection of days to 50% flowering and positive selection of weight of dry biomass, and to improve essential oil contents positive selection of days to 50% flowering severely are highly recommended.

Holocene vegetation history and sea level changes in the SE corner of the Caspian Sea: relevance to SW Asia climate

The palynological investigation of core TM (27.7 m long) taken in a dried out lagoon reveals both Holocene vegetation history in the north-eastern foothills of the Alborz Mountains and past water level changes of the Caspian Sea (CS).The delay in woodland expansion at the beginning of the Holocene, which is typical of eastern Turkey, the Iranian plateau and recorded in the CS south basin, is only weakly felt as the region is close to glacial refugia of trees.The succession of the main trees out of their refugia has been established as deciduous Quercus, Carpinus betulus, Parrotia persica, and Fagus orientalis-Pterocarya fraxinifolia, presenting therefore close affinities to south European interglacials of the Early Pleistocene. This suggests a similarity in climate.A Pterocarya decline is observed after AD 495. The studied region is close to the easternmost tree distribution; this could explain why it has been affected earlier than elsewhere in the northern Alborz and the Caucasus. In addition human activities during the Sasanian Empire and the subsequent drying of the climate contributed to weakening the spread of this tree.A maximal sea level occurs in the first part of the Holocene from 10.6 to 7.2 cal. ka. It is suggested that the CS levels were significantly influenced by the monsoon precipitations over the western Himalayas (via the Uzboy inflow). This is followed by low levels from 7.2 to 3.5 cal. ka with a minimum at 3.9 cal. ka.The Neocaspian period should be considered a biozone rather than a chronozone, as the environmental conditions reconstructed from dinocyst assemblages are different in shallow shelf waters and in the deep basins.

Biostratigraphy and Mass Extinction Pattern across the Cretaceous/Paleogene Boundary, Northern Alborz, Iran

High resolution sampling across the Cretaceous/Paleogene boundary (K/Pg) at the Galanderud section in northern Iran provides the most expanded and continuous section for us to consider biostratigraphy and the mass extinction pattern of Cretaceous planktic foraminifera. Based on planktic foraminifera, four biozones and five sub-biozones have been identified across the K/Pg boundary. These biozones include the Abathomphalus mayaroensis Biozone (Plummerita hantkeninoides subbiozone), the Guembelitria cretacea Biozone (including two sub-biozones: the Hedbergella holmdelensis and the Parvularugoglobigerina longiapertura), the Parvularugoglobigerina eugubina Biozone (including two subbiozones: the Parvularugoglobigerina Sabina and the Eoglobigerina simplicissima) and finely the Parasubbotina pseudobulloides Biozone. Planktic foraminiferal extinction occurred over a brief period, with 3% of the species disappearing in the late Maastrichtian, and 72% of the species becaming extinct at the K/Pg boundary. About 25% of the species survived into the early Danian. Extinction of 73% of the species at the K/Pg boundary is very compatible with the effect of a large asteroid impact.

A Probabilistic Model for Presence of Eurasian Nuthatch (Sitta europaea) in the Alborz Mountains, Northern Iran

Abstract Hyrcanian forests in the northern Alborz Mountains contain many resident and migrant passerines, but the ecological relationships of the species are obscure. We identified the ecological factors (forest structure, type, and topography) that could explain the distribution of the Eurasian Nuthatch (Sitta europaea) and its' habitat suitability in this region. Significant habitat parameters for presence-absence of Eurasian Nuthatch were height, diameter, stand, and type of trees. Our model successfully predicted the presence probability of nuthatches and that suitable habitats strongly depend on abundance of old trees, especially Oriental beach (Fagus orientalis) and European hornbeam (Carpinus betulus). These data suggest forest structure is the key factor in bird habitat use and suitability, and reveal the necessity of adaptive logging activities in Hyrcanian forests.

Detection of ecotone environment based on satellite and field techniques (A case study; Northern Alborz, Iran)

Environmental change and socio-economic pressure are expected to have significant impacts on Northern Alborz vegetation, particularly along ecotone such as the treeline. Remote sensing may be well suited to monitoring recent changes across the treeline because it captures integrated changes of all vegetation life forms over large spatial extents. This research examines treeline vegetation composition and change along the Nojmeh treeline using a high resolution, ETM+ 2000. In this paper we investigate the use of satellite data to produce a classification of a treeline ecotone in Northern Alborz Mountains which has supported the field investigation as ground truth data collected in the summers from 2008 to 2010. The maximum correlation is related to the Bands 3 and 4 of Landsat ETM+ with shrubs canopy cover that indicated in r of 0.34 and 0.37 respectively. The maximum rate of correlation in respect to the indices were recognized for the vegetation cover of moisture stress index (MSI) for forbs cover (r= 0.62). The ratio vegetation index (RVI) for grasses cover was indicated (r= 0.53). In conclusion, the results are specified that the ETM+ sensor is the significant data with the elevated competence to discrimination of ecotone using vegetation indices. Key words: ETM+, classification, ecotone, treeline, Alborz, Iran.

Physical characteristics of spectrums and field techniques in detection of ecotone (a case study of Northern Iran)

Environmental change and socio-economic pressure are expected to have significant impacts on northern Alborz vegetation, particularly along ecotone such as the treeline. Remote sensing may be well suited to monitoring recent changes across the treeline because it captures integrated changes of all vegetation life forms over large spatial extents. This research examines treeline vegetation composition and change along the Nojmeh treeline using a high resolution, enhanced thematic mapper (ETM+) 2000. In this paper, we investigate the use of satellite data to produce a classification of a treeline ecotone in Northern Alborz Mountains which has supported with the field investigation as ground truth data collected in the summers from 2008 to 2010. The maximum correlation is related to the bands 3 and 4 of Landsat ETM+ with shrubs canopy cover that indicated in r of 0.34 and 0.37, respectively. The maximum rate of correlation respect to the indices were recognized for the vegetation cover of moisture stress index (MSI) for forbs cover (r = 0.62). The ratio vegetation index (RVI) for grasses cover was indicated (r = 0.53). In conclusion, the results are specified that the ETM+ sensor is the significant data with the elevated competence to discrimination of ecotone using vegetation indices. Key words: Electromagnetics, satellite, classification, ecotone, Alborz, Iran.