Northern Boundary Research Articles

Preliminary data on the diet of Chalcides chalcides (Squamata: Scincidae) from Northern Italy

The diet in skinks is known mainly for extra-European species, especially from Australian ones, where these lizards are represented by a great number of species, while, in comparison, data for species from other continents are scarce. The three-toed skink, Chalcides chalcides, is found in a restricted part of northern Africa and in Italy, where it is distributed almost uniformly throughout the peninsula and on the major islands. Although it is well studied for aspects such as morphology and ecology, data concerning trophic preferences are scarce, and available only for the populations of south-central Italy. In this note we report preliminary data about the diet of an Apennine population of the three-toed skink, Chalcides chalcides, at the northern boundary of its distribution area. Faecal contents from 20 individuals were collected in June 2015, obtaining an overall sample of 48 prey items. Araneae constituted the most preyed taxon (over 40%), followed by Hemiptera (35,4%) and other prey taxa (Hymenoptera, Coleoptera, and Dermaptera) in much lower percentages. We found no differences between smaller/younger and larger/older individuals in consumed preys. As well as confirming the general trophic predilection of this skink for spiders, we also found some interesting differences in preyed items with studied populations of south-central Italy.

Asymmetric Interseismic Strain across the Western Altyn Tagh Fault from InSAR

As the northern boundary of the Tibetan Plateau, the long Altyn Tagh fault (ATF) controls the regional tectonic environment, and the study of its long-term fault slip rate is key to understanding the tectonic evolution and deformation of the northern Tibetan Plateau. In this paper, we measure the fault slip rate of the western segment of the ATF using InSAR observations between 2015 to 2020. The Multi-Temporal Interferometric InSAR analysis is applied to obtain the two-dimensional fault-parallel and vertical displacement fields. The spatially dense InSAR observations clearly illustrate the asymmetrical pattern of displacement fields across the fault. Constrained by our InSAR observations, the fault slip rate and locking depth of the western segment of the ATF are inverted using four different models in a Bayesian framework. The two-layer viscoelastic model incorporating lateral heterogeneity of rheology in the lower crust indicates that the fault slip rate of the western ATF is estimated to be 9.8 ± 1.1 mm/yr (at 83.8°E across the ATF) and 8.6 ± 1.1 mm/yr (at 85.1°E), respectively, and the locking depth is 15.8 ± 4.3 km and 14.8 ± 4.9 km. Our new estimates generally agree with the previous estimates of fault slip rate constrained by GPS observations. We conclude that the contrast between the thickness of the elastic layer and the shear modulus of the Tibetan plateau and the Tarim basin jointly contribute to the asymmetric interseismic strain accumulation on the ATF.

Lithospheric Structures beneath the Tibetan Plateau Constrained by Sn Propagation Efficiency

Abstract The uppermost mantle is a crucial region linking the lower crust and lithospheric mantle and carries important dynamic and structural information (e.g., upwelling and delamination) on interactions between the crust and mantle. An intriguing observation of an inefficient Sn wave zone beneath the Tibetan Plateau was reported but had unclear spatial distributions. By analyzing the Sn wave propagation efficiency from 34,917 Sn wave arrivals, we provide strong constraints on the lateral and depth variations in the inefficient Sn wave zone in the Tibetan Plateau. Our results show that with increasing frequencies, the inefficient Sn wave zone becomes larger, expanding to the eastern Songpan-Ganze terrane and then to the Sanjiang area and the southern margin of the Qilian orogenic belt. The northern and eastern boundaries of the inefficient Sn zone, particularly a small inefficient zone in the Qilian orogenic belt (37°N, 102°E), are clearly depicted, indicating the widespread distribution of the seismic attenuation structure or partial melt in the uppermost mantle. Moreover, we provide the depth variations in the inefficient Sn wave zone by simulating 31,538 3D raypaths with the fast marching method. We therefore constrain the depth range of the partial melt region in the uppermost mantle beneath the Tibetan Plateau. The seismic attenuation structure in the northern-central Qiangtang terrane and western Songpan-Ganze terrane extends to 130 km from the bottom of the crust, whereas that in the eastern Songpan-Ganze terrane and Sanjiang area is thinner and mainly concentrated from 90 to 130 km. Combining this information with the temporal and spatial variations in potassic-ultrapotassic magmatic rocks, it is suggested that asthenospheric materials might upwell and flow laterally beneath the Tibetan Plateau. This behavior provides a thermal driving force for the uplift of the plateau and the deformation of the crust-mantle structure.

Ground Penetrating Radar (GPR) survey over a melting blue ice area (BIA) at the south of Schirmacher Oasis, Dronning Maud Land, East Antarctica

A blue ice area (BIA) is located in Dronning Maud Land, East Antarctica between Schiermacher Oasis (SO) and Ulthat mountain ranges. High-resolution ground-penetrating radar (GPR) survey has been carried out in the northern boundary of the BIA surrounded by Schirmacher Oasis (SO), Shivalinga and Veteheia nunataks to examine if the BIA in the area is wind-induced or melt-induced in nature. GPR study reveals that the glacier in this part of BIA is warm and showing prominent signatures of subsurface melting in the vicinity of the nunataks and other exposed rock masses. The signatures of bottom warming also have been detected in few profiles which are in agreement with the drilling results in nearby areas. Melting signatures vary over the area depending on the distances from the exposed rocks and proximity of subglacial bedrock topography. The results indicate the possible higher heat supply by the exposed rock mass to the BIA. Folding of the internal layers and the presence of two firn pockets also have been observed near the nunatak Veteheia. The present GPR study concludes that the survey area is predominantly melt-induced BIA. Further investigations are recommended to study the firn pockets and mass balance of the area.

Changes in the Northern Boundary of the Eurasian Beaver (Castor fiber Linnaeus, 1758, Rodentia, Mammalia) Range on the Yamal Peninsula (Western Siberia) during the Holocene

Changes in the Northern Boundary of the Eurasian Beaver (Castor fiber Linnaeus, 1758, Rodentia, Mammalia) Range on the Yamal Peninsula (Western Siberia) during the Holocene

Protection effectiveness and sea urchin predation risk: The role of roving predators beyond the boundaries of a marine protected area in the Western Mediterranean Sea

Abstract Effective marine protected areas (MPAs) increase top predator density. Accordingly, a large abundance of predatory fish potentially increases predation risk for sea urchins inside an MPA. Intensity of predation was investigated for the sea urchin Paracentrotus lividus at a Mediterranean MPA. Predation rates were estimated for three levels of protection (full, partial, and absent) and two habitats (rocky reefs and Posidonia oceanica meadows). The natural density of sea urchins was correlated with predator biomass (fish sparids Diplodus spp. and Sparus aurata and the gastropod Hexaplex trunculus), and predation risk was evaluated through a tethering experiment. Significantly higher fish predation was found on the rocky reefs of the fully and non‐protected areas than in the partially protected area. These findings are consistent with the sparid biomass estimated in the fully and partially protected areas. However, a discrepancy between high predation risk and low sparid biomass was detected outside of the MPA's northern boundary, where marine farms (fish and mussels) are present. Benthic predator biomass also increased significantly across the northern boundary, but its predation activity was negligible. The low predatory fish biomass and low sea urchin density suggest a top‐down control by roving predatory fish on the rocky reefs of the non‐protected area, in proximity to the fish farms. Similarly, a significant gradient of benthic predator biomass and low sea urchin density suggest potential predation interactions inside the P. oceanica meadows across the northern MPA boundary near the mussel farms. This study highlights deviations from the expected trophic interactions outside the MPA that could be caused by aquaculture activities. Our understanding of the potential synergies between the MPAs and the nearby human activities needs to be broadened to improve the effectiveness of both ecosystem conservation and resource management.

Cloud water path, precipitation amount, and precipitation efficiency derived from multiple datasets on the Qilian Mountains, Northeastern Tibetan Plateau

Orographic clouds and precipitation are critical to the water cycle and ecology of arid and semiarid mountainous regions. This study intended to investigate the spatial and seasonal distribution of the cloud water path (CWP), precipitation amount, and precipitation efficiency (PE) on the Qilian Mountains (QM) of the northeastern Tibetan Plateau, as well as the related mechanisms linked with topographic distribution and water vapor transport. To solve the limitations of rain gauges and radar observations at high elevations of the QM, we used the latest multiple datasets, including the Global Precipitation Measurement (GPM), Advanced Very High Resolution Radiometer, and ECMWF Reanalysis v5 data from 2016 to 2019. The amount of precipitation retrieved from the two GPM products was evaluated using rain gauge data. The results show that the GPM data generally overestimate the precipitation amount on the QM and have a high correlation with rain gauge data in warm seasons and a low correlation in winter seasons, primarily due to the significant influences of snow and ice coverage. The terrain height and water vapor supply below 600 hPa are two critical factors that determine the spatial and seasonal distributions of clouds and precipitation in the QM. The precipitation generally increased with an increase in terrain elevation below 3000 m and decreased above 3000 m on the QM. CWP, precipitation amount, and PE in the mountainous areas are much higher than those in the surroundings and decrease from the southeast to the northwest because of the decrease in low-level water vapor supply. CWP, precipitation amount, and PE were the highest in summer because of the strong moisture transport from the southeast and the lowest in winter because of the weakest water vapor transport. Water vapor fluxes from the eastern, southern, and northern boundaries contributed to the wetness of the eastern and northeastern slopes of the QM. The lack of low-level water vapor in the westerly winds was the main reason for drought in the western QM.

Recurrence and Clustering of Large Earthquakes along the Northern Boundary of Ordos Block: Constraining Paleoearthquakes by an Improved Multiple Trench Constraining Method

AbstractTectonic belts along active tectonic block boundaries comprise one or more active faults; along which, large earthquakes recur. Therefore, it is important to establish the recurrence behavior of large earthquakes along such boundary zones for studying their characteristics and developments. Many paleoearthquake studies make it possible to investigate the recurrence behavior of large earthquakes along the northern boundary of the Ordos block (NBOB). Based on the previous studies, data from 52 trenches were collected to reconstruct prehistoric earthquakes using an improved multiple trench constraining method. This method is based on paleoearthquake indicators and trench location distribution to constrain the rupture time and length, thereby reducing the selection bias of fixed rupture length to construct additional rupture scenarios. The results suggest that the NBOB comprises four normal faults (from west to east): the Langshan Piedmont Fault (LPF), Sertengshan Piedmont Fault (SPF), Wulashan Piedmont Fault (WPF), and Daqingshan Piedmont Fault (DPF); along which, six, seven, eight, and six paleoearthquakes have occurred within approximately 15,000 yr, respectively. In addition, recurrence behaviors of the individual faults exhibit remarkable periodicity. The regional fault network along the NBOB reveals clustered characteristics with six clusters propagating either westward or eastward and a recurrence time of approximately 1,300 yr. Large earthquake events have occurred along the LPF, WPF, and DPF according to the most recent cluster; however, earthquakes were absent along the SPF, and no evidence of large earthquakes was observed along the NBOB after the 849 CE earthquake. Thus, we discuss the possibility of occurrence of large earthquakes along the SPF after the 849 CE earthquake based on earthquake recurrence and cluster migration behavior. Additional research is required to assess the potential risk of the occurrence of a large earthquake along the SPF in the future.

АДАПТАЦИИ ВИДА К ОБИТАНИЮ НА ПЕРИФЕРИИ АРЕАЛА: ОБЗОР ОСОБЕННОСТЕЙ БИОЛОГИИ ПОЛЧКА (GLIS GLIS LINNAEUS, 1766) В САМОЙ ВОСТОЧНОЙ ПОПУЛЯЦИИ

Marked peculiarities in the biology of a species that may be observed, possibly regardless of genetic changes, on the periphery of the species habitat may provide for species survival under extreme conditions. The same may be relevant to populations that are isolated, marginal, or remote from the main distribution range of a species. With this in mind, several biological features of the edible dormouse were studied. This rodent species features a vast distribution range in Europe and partly in Asia. Differentiation into subspecies is mostly not observed within the range. This allows comparing the biology of a single species over significantly distant areas. The range of biotope preferences of the dormice on the periphery of their distribution is wider than in the central areas. In the former cases, these rodents were found in forests featuring a significant proportion of birch and aspen in the forest stand. These observations are similar to those on the northern boundary of the dormouse distribution range in Poland and Lithuania. Some specific features of the diet of the species are associated with these habitats. In the Zhiguli Mts. (Russia) and Lithuania, the main diet includes birch seeds. At the same time, fruits and berries, which are of major importance in the other parts of dormice distribution range, are completely absent among the juicy forages. These differences probably underlie the development of a unique mechanism of reproduction control, which is not observed in other mammalian species. On the periphery of the distribution range, the number of sources of the basic forages for the highly specialized species under study is increased compared to the rest of the distribution area, and the reproductive activity of dormice is annual. However, upon the absence of a sufficient amount of the high-calorie food, mass embryonic resorption in most of females occurs. In addition, in the easternmost population, a higher territoriality is featured by females rearing offspring, and the phenomenon of communal nesting by related females is not observed. To confirm whether the genetic or environmental factors are at the base of the biological features described, large-scale population genetic studies are warranted. At the present stage, field studies allow tracing analogous features in other parts of the species habitat and thus help illustrating the ecological plasticity of the oligophagous species under suboptimal conditions.

Exploration discovery and hydrocarbon accumulation characteristics of the Doseo strike-slip and inverted basin, Chad

Several international oil companies had conducted petroleum exploration, but failed to make any commercially viable discoveries in the Doseo Basin for over 30 years. In this article, an integrated analysis, based on the latest seismic and drilling data combined with exploration practice and tectonic, sedimentary as well as petroleum-geological characteristics of the basin, has been conducted with the aim to disclose the key factors of hydrocarbon accumulation and enrichment and then to find the potential petroleum plays. The Doseo Basin in Chad is a Meso-Cenozoic lacustrine rift basin developed on the Precambrian crystalline basement in the Central African Shear Zone. It is a half graben rift controlled by the strike-slip fault at the northern boundary, and can be divided into two sub-basins, an uplift and a slope. The basin experienced two rifting periods in the Cretaceous and was strongly inverted with the erosion thickness of 800–1000 m during the Eocene, and then entered the depression and extinction period. Structurally, a large number of normal faults and strike-slip faults are identified in the basin, and the boundary faults are inverted faults with normal at first. The main structural styles include inverted anticlines, fault noses, complex fault-blocks and flower structures. The Lower Cretaceous is the main sedimentary strata, which are divided into the Mangara Group, Kedeni, Doba and Koumra Formations from bottom to up. Two transgressive-regressive cycles developed in the Lower Cretaceous indicates with mainly lacustrine, fluvial, delta, braided-delta, fan-delta sandstone and mudstone. The effective source rock in the basin is the deep-lacustrine mudstone of the Lower Cretaceous containing the type I and type II1 organic matters. Furthermore, Inverted anticlines and fault-complicated blocks comprise the main trap types and the Kedeni Uplift is the most favorable play, followed by the Northern Steep Slope and Southern Gentle Slope. Lateral sealing capacity of faults controls the hydrocarbon abundance.

Moisture transport and water vapour budget over the Sahara Desert

AbstractPrevious studies documented that near‐surface temperatures over the Sahara and Arabian deserts have been amplified in a warming climate, which is termed desert amplification (DA). DA has been linked possibly to the large‐scale greenhouse effects associated with increasing water vapour. With very limited moisture availability over the driest desert, two key questions unanswered are the desert moisture sources and the relative contributions of thermodynamic and dynamic processes to the changes in moisture transport. In this study, the atmospheric water vapour budget over the Sahara Desert from 1981–2020 is analysed to address these two questions. Results indicate that the water vapour content over the Sahara Desert has increased significantly since 1981, primarily during the boreal summer and in the lower to middle troposphere. The water vapour budget analysis indicates that in the boreal summer, most of the added moisture is transported into the Sahara Desert through the intensifying northerly inflow across the northern boundary of the desert, while the other boundaries are all export channels. The northerly inward moisture transport is associated with the ridge in the lower troposphere and the Saharan high above the lower troposphere. Further analysis indicates that both dynamic and thermodynamic factors contribute to the increase of the inward moisture flux at the northern boundary, while the associated interannual variability is dominated by the dynamic component related to the circulation pattern changes. The changes of the circulation pattern in the lower troposphere are manifested as the westward extension of the low over the Arabian Peninsula and as the strengthening of the Saharan high above the lower troposphere, both contributing to the increase of the northerly inward moisture transport.

Understanding the Limiting Climatic Factors on the Suitable Habitat of Chinese Alfalfa

Chinese alfalfa (Medicago sativa) is one of the most widely planted species in China. It has considerable economic potential and plays an important role in soil and water conservation. In order to conduct scientific cultivation of Chinese alfalfa, we collected 100 occurrence records from herbarium and publications and 19 climatic variables from BIOCLIM to simulate potential suitable habitat and identified the key climatic factors of Chinese alfalfa by MaxEnt and GIS software. The result shows that the MaxEnt model performed well, with an average test AUC value of 0.86 with 10-fold cross validation. The potential distribution of Chinese alfalfa is mainly in arid and semi-arid areas of north and northwest China, about 15.2% (1.46 million km2) of China’s total land area, and the highly suitable area is Loess Hilly region and Xinjiang. The main climatic factors affecting the distribution of this species is hydrological-related factors (PDM, PS, AP, PDQ and PCQ), which explained 58.6% of the variation, and the climatic factors limiting the southern, northern, northwestern and Tibetan plateau boundaries were PDM, AMT, AP and MTCM, respectively. The climatic thresholds of the core area of Chinese alfalfa are 0.0–14.0 mm of PDM, 23.8–108.2% of PS, 3.9–15.5 °C of AMT, 14.0–664.0 mm of AP, 1.0–47.0 mm of PDQ, 2.0–51.0 mm of PCQ. The results improve our understanding of limiting climatic factors for Chinese alfalfa and suggest a priority management measures for areas with corresponding limiting climatic factor.

Branches of the Karakoram fault in Eastern Pamir

ABSTRACT The tectonic evolution of the Karakoram fault in the Pamir Plateau is controversial because the timing and kinematics of several branches of the fault system are unclear. Here we conduct field observations on the East Pamir fault, the North Muskol shear zone, and the Xindi-Waqia fault in the eastern Pamir, and obtain zircon U-Pb and biotite 40Ar/39Ar ages from these ductile shear zones. All three faults/shear zones are hosted by granitic mylonites. The East Pamir fault is a northwest-striking, normal-dextral shear zone that cuts the Rushan-Pshart suture. Zircon U-Pb dating yields a mean age of 201.5 ± 0.5 Ma for the mylonites in this shear zone. Biotite 40Ar/39Ar analysis yields two weighted mean plateau ages, 10.65 ± 0.13 Ma, and 11.04 ± 0.15 Ma. An undeformed granitic vein that cuts the ductile shear zone gives a mean zircon U-Pb age of 9.6 ± 0.3 Ma. We interpret that the granitic protolith crystallized at 201.5 Ma, and the East Pamir fault underwent rapid cooling and exhumation at ca. 11 Ma and ceased by 9.6 Ma. The North Muskol shear zone is an east-striking extensional shear zone along the northern boundary of the Shatput-Muztaghata dome. Two mylonitic samples show mean 206Pb/238U ages of 17.9 ± 0.2 Ma and 17.6 ± 0.3 Ma, which are interpreted as the timing of crystallization of the granitic protolith. The Xindi-Waqia fault is a northwest-striking ductile shear zone and brittle fault that bounds the Muztaghata dome. We obtain two zircon U-Pb ages (231.8 ± 1.1 Ma, 235.9 ± 0.9 Ma) and two biotite 40Ar/39Ar plateau ages (between 6.60 ± 0.10 Ma and 6.87 ± 0.10 Ma) from the mylonites in this fault, and interpret that the granitic rocks were emplaced in the Late Triassic and exhumed in the late Miocene. The newly obtained U-Pb ages, combined with the previously published data, indicate that Rushan-Pshart suture in Pamir marks the closure of an ocean basin within the Palaeo-Tethys Ocean, and cannot be correlated with the Bangong-Nujiang suture in Tibet. We establish a systematic correlation in which the two Palaeo-Tethyan sutures (Tanymas-Jinshajiang and Rushan-Pshart) in Pamir represent the western extensions of the Jinshajiang and Longmu Co-Shuanghu sutures in the Tibetan Plateau, respectively, and the Central Pamir is the western extension of the Tianshuihai-North Qiangtang terrane. This indicates that the dextral slip along the Karakoram fault system in east-central Pamir is 140 ± 10 km, and the mean slip rate since the onset of the Karakoram fault at ca. 18 Ma is 7.8 ± 0.5 mm/yr. Furthermore, our analyses suggest that the North Muskol shear zone was active at ca. 18 Ma before the arrival of the Karakoram fault system then. The East Pamir fault must have been active at ca. 11 Ma, but ceased by ca. 9.6 Ma, and the slip along the Karakoram fault system migrated northeastward and primarily accommodated by the Tashkurgan fault soon after 9.6 Ma. The Xindi-Waqia fault is the southern extension of the ductile shear zone of the Kongur Shan extensional system, as they are highly similar in geometry, kinematics, and timing. Overall, as the Karakoram fault system propagated northward in Pamir during the Cenozoic, crustal deformation migrated northeastward among the Karakoram fault branches from Ladakh to the Kashgar-Yecheng transfer system, and a complex evolution path can be portrayed.

S-type like granites and felsic volcanic rocks in the Mahabad area, NW Iran: Late Neoproterozoic extensional tectonics follow collision on the northern boundary of Gondwana

The Late Neoproterozoic basement is exposed in the Mahabad area of northwest Iran, and it is classified into three main groups. The first is metamorphic rocks that include gneiss, schist, phyllite, and slate. The second is sedimentary rocks, which comprise shale, sandstone, and dolomite and the third is igneous rocks including granite, rhyolite, felsic tuff, and ignimbrite, which are the subject of this research. Zircon UPb ages for three igneous samples show that crystallization occurred at 558–552 Ma in the late Neoproterozoic (Ediacaran). The felsic magmatic rocks have SiO2 contents of 64.3 to 78.9 wt%, Al2O3 contents of 12.0 to 16.8 wt%, low TiO2 contents (0.08 to 0.69 wt%), and large variations in K2O (0.05 to 5.46 wt%) and Na2O (1.17 to 6.70 wt%). The felsic magmatic rocks are enriched in light rare earth elements (REEs) such as La and Sm, have flat heavy REE patterns, and strong negative Eu anomalies. They are mainly weakly to strongly peraluminous and calc-alkalic to alkali-calcic rocks. A wide range of initial 87Sr/86Sr(556Ma) ratios (0.7056 to 0.7203) and negative εNd(t) values (−6.0 to −2.9) do not show clear trends of mixing/contamination among mantle, slab fluids, and/or altered oceanic crust. The Mahabad magmatic rocks were produced mainly by partial melting of graywacke, psammite, and shale at high temperatures (~800 °C), based on the zircon saturation index. S-type like granites usually form in syn- to post-collisional systems, but the Mahabad felsic rocks, which have almost the same ages as the associated sedimentary rocks, were generated in an extensional regime according to geochemical discrimination diagrams. This can be explained as follows: sediments were deeply buried during the late Neoproterozoic amalgamation of microcontinents at a subduction zone along the northern boundary of Gondwana, and then erosion of the roof and/or thinning owing to extension led to upwelling of the asthenosphere and intrusion of mafic magma, which was responsible for partially melting the buried metasedimentary rocks to generate S-type like granites and felsic volcanic rocks.

From Left Slip to Transpression: Cenozoic Tectonic Evolution of the North Altyn Fault, NW Margin of the Tibetan Plateau

AbstractThe Cenozoic North Altyn Fault (NAF) is a major splay of the Altyn Tagh Fault along the northwestern margin of the Tibetan Plateau, but its role in the development of this plateau margin in response to the India‐Eurasia collision is highly debated. Here, we investigate fault geometry, kinematics, and shortening magnitude along the westernmost 120 km of the NAF. Seismic surveys reveal minimal Cenozoic shortening in the subsurface of the Southeast Tarim Basin and support for large‐scale (>120 km) left slip on the NAF. Based on the satellite imagery, two new faults are identified to define the northern boundary of the NAF system, which together with the NAF to the south constitute a narrow transpressional shear zone comprised of three basement‐cored, fault‐bound slivers. Fission track data and thermal modeling indicate that the NAF zone experienced broad reburial during early Cenozoic that was locally interrupted by ∼40 to 35 Ma exhumation proximal to the NAF, followed by widespread but heterogeneous exhumation since ∼17 to 15 Ma associated with ∼9 to 11 km of total shortening across the NAF system via thick‐skinned faulting. We conclude that the NAF initiated as a left‐slip fault at ∼40 to 35 Ma and then became transpressional at ∼17 to 15 Ma during the middle‐Miocene reorganization of the Altyn Tagh Fault system. We find no evidence to support prior inferences of large‐scale (∼100 km) underthrusting of the Tarim Basin beneath the Tibetan Plateau along the NAF.

The Formation of the Species Structure of Plant Communities on the Northern Boundary of the Krasnoyarsk Forest–Steppe over the Last 6000 Years

The Formation of the Species Structure of Plant Communities on the Northern Boundary of the Krasnoyarsk Forest–Steppe over the Last 6000 Years

History of the Hickiwan District, Tohono 'O'odham Nation

History of the Hickiwan District, Tohono 'O'odham Nation Harry J. Winters Jr. (bio) The lands of the Tohono 'O'odham Nation are divided into 11 districts. The district boundaries reflect ancient patterns of ownership and use of natural resources such as farmlands, watering places, and areas for gathering food plants by different groups of Tohono 'O'odham. The Nation is governed by a Tribal Council with a tribal chairperson and a vice chairperson. All 11 districts are represented on the council. Each district has its own District Council with a district chairperson and a district vice chairperson. The Hickiwan District headquarters is at the village Vavhia Chiñ, Mouth Of The Well. This history is dedicated to the 'O'odham of the Hickiwan District. Many 'O'odham of younger generations are not familiar with the vocabulary used by their ancestors and even their grandparents and parents. One purpose of this history is to help them learn some of those old words which were so important to their elders. A list of 'O'odham words used in this history and their meanings is appended at the end of the history. If the meaning of a word or name is not in the text, look in that appendix. Location of the Hickiwan District The Hickiwan District is the most northwestern of the nine contiguous districts that include most of the Tohono 'O'odham Nation lands in the United States. The district's maximum dimensions are about 30.3 miles from the northeast corner to the southeast corner and about 28.6 miles east to west. The northernmost point of the district is in the Sauceda Mountains near the mouth of Couger Canyon and less than a mile [End Page 100] southwest of the mountain 'E'eḍ Vahudam, Barn Owl. This point is also about 1.75 miles southwest of the junction of two extremely important old 'O'odham trails at the hill 'Eḍa Kavolik, Kavolik In The Middle, so named because it sits right between those two trails and immediately southeast of their junction. See the Hickiwan District map. Click for larger view View full resolution Hickiwan District Map From the northwestern corner the boundary runs east across the southern end of the Sand Tank Mountains to a point about 5.5 miles north of Gagga village, spelled Kaka on U.S. Geological Survey maps [End Page 101] and meaning Clearings For Fields. At that point it turns north for 3 miles and then turns south-southeast and follows a slightly irregular course to the site of the old village Moik Vavhia, Soft Well, so named because digging the ground for the well was easy. Moik Vavhia was the easternmost well village of the people of Gagga as recently as the first part of the 20th century. From Moik Vavhia the boundary follows a zigzag course to the southwest, passing just east of the village Vavhia Chiñ, Mouth Of The Well. At a point 4 miles southwest of Vavhia Chiñ the boundary turns south-southwest and runs to a point less than a mile south of Arizona State Route 86 from Tucson to Ajo. At that point the boundary turns west for about 17.5 miles, passing just south of Nine Mile Peak, Bihinolik in 'O'odham, and passing between the old Gunsight mine on the south and S-Chuchuligk village on the north until it reaches the western boundary of the Hickiwan District and the Nation's lands. The name Bihinolik comes from the shape of the little butte. It looks like something wrapped up and slumped over. S-Chuchuligk means Place With Lots Of Chickens. It is also called Gunsight after the old mine. For its entire length, the northern boundary of the district lies along the southern boundary of the U.S. Air Force Barry M. Goldwater Range, in an active tactical area of that range. Establishment of the range, formerly known as the Luke Air Force Range, in 1941 cut off direct access of the Tohono 'O'odham from the villages in the Hickiwan District to the Lower Gila River via two ancient trails. For centuries those trails were very important to 'O'odham...

Research on deformation characteristics of the 2021 Qinghai Maduo MS7.4 earthquake through coseismic dislocation inversion

Over the past 70 years, the Qinghai Maduo Ms7.4 earthquake (May 22, 2021) has been the only earthquake with a magnitude of ≥7 that has occurred within the Bayan Har Block. To investigate the deformation process of this earthquake, we acquired the Interferometric Synthetic Aperture Radar (InSAR) coseismic deformation field based on Sentinel-1 SAR images, which showed that the maximum line of sight (LOS) displacement was ~1 m. By combining this information with the results of our field investigation, the fault slip distributions were obtained by inversion using the single- and double-fault models, wherein the latter model showed better inversion results than that of the former. According to the inversion results, the overall rupture pattern was predominantly left-lateral strike-slip, with a released seismic moment of ~Mw7.5. Specifically, the principal seismogenic fault had a strike of 283°, dip of 91°, and maximum slip of 4.87 m; the branch fault along the eastern segment of the rupture had a strike of 110°, dip of 94°, and maximum slip of 2 m. Conversely, the results derived from the Global Navigation Satellite System (GNSS) strain rate field before the earthquake indicated that the Maduo earthquake occurred in East Kunlun,which is characterized by the largest maximum shear strain rate. The strain accumulation rate (~2.5 × 10−8/yr) was significantly lower than that of the Xianshuihe fault zone on the southern boundary of the Bayan Har block and the East Kunlun fault zone on its northern boundary. Furthermore, pre-seismic deformation near the seismogenic fault was relatively gentle, showing partial late seismogenic characteristics.

ECOLOGICAL AND GEOGRAPHICAL ANALYSIS OF DISTRIBUTION OF <i>HERACLEUM PERSICUM</i>, <i>H. MANTEGAZZIANUM</i> AND <i>H. SOSNOWSKYI</i> ON THE NORTHERN LIMIT OF ITS SECONDARY RANGE IN EUROPE

The group of plants known as giant hogweeds: , and are widely recognized as dangerous alien species in Europe. We have analyzed the climatic conditions on the northern boundary of the secondary range of giant hogweeds group species in Northern Europe. The northernmost areas of growth of H. persicum are localized in the coastal regions of the northern and central parts of the Scandinavian Peninsula (up to 71° NL). Within Fennoscandia, the plants and were found up to 69° NL. The natural gradient of climatic parameters within the subarctic and temperate zones in Northern Europe allowed us to assess the ranges of climatic conditions required for the plants in this territory. We have found that the minimum sum of active temperatures values required for these alien plants are >1150 °С (for temperatures above 5 °C) and >450 °С (for temperatures above 10 °C). The heat resource exceeding this level ensures successful growth, development and reproduction of giant hogweeds group species in the climatic conditions of Subarctic Europe. The presence of stable snow cover on the territories with very low air temperatures during winter period prevents buds and seedlings cold damage. Climatic indices calculated as ratio of air temperature and snow depth or winter precipitation can serve as markers reflecting climatic constraints for the expansion of alien giant hogweeds group species in north direction. The main climatic parameters limiting the distribution of these species in Northern Europe are: insufficient sum of active temperatures, seasonal freezing of soils to temperatures critical for wintering organs of plants, late spring and early autumn frosts.

Holocene Millennial‐Scale Precipitation Variations in the Asian Summer Monsoon Margin of Northwest China and Their Relation to Migrations of Monsoon Northern Boundary via Oxygen Isotope Analysis of Calcareous Root Tubes in Deserts

AbstractThe Asian summer monsoon (ASM) margin of northwest China is a critical region for studying Asian monsoon variability during the Holocene. However, the pattern of precipitation variations and migration of the ASM northern boundary in arid regions during the Holocene remains unclear. In this study, we analyzed oxygen isotopes of 70 calcareous root tube (CRT) samples from the desert hinterlands in the ASM margin of northwest China, including the Badain Jaran, Tengger, Ulan Buh, and Kubuqi deserts. The CRT samples were analyzed to reconstruct millennial‐scale precipitation variation patterns during the Holocene and further explored the location of the ASM northwestern boundary during the middle Holocene. Our results demonstrated that the δ18O values of CRTs during the late Holocene (4.0–1.0 cal kyr BP) were all less negative than those during the middle Holocene (8.0–4.0 cal kyr BP), which revealed that the precipitation decreased from the middle Holocene to the late Holocene. Moreover, an increase in δ18O values from the southeast to northwest revealed that the precipitation decreased. We argued that the Holocene millennial‐scale precipitation changes in this region were influenced by the migrations in the ASM northern boundary. During the middle Holocene, due to the strong summer solar radiation and reduced ice sheets, the ASM northern boundary in the arid region advanced by at least 250 km to the northwest, which resulted in increased precipitation. During the late Holocene, the ASM northern boundary retreated southeastward, resulting in decreased precipitation.