Distinct Orogenic Processes in the South‐ and North‐Central Tien Shan From Receiver Functions

2020 ◽  
Vol 47 (6) ◽  
Author(s):  
Bingfeng Zhang ◽  
Xuewei Bao ◽  
Yixian Xu
2020 ◽  
Author(s):  
Xuewei Bao ◽  
Bingfeng Zhang ◽  
Yixian Xu

<p>Uplifting mechanisms for the Tien Shan, an active intracontinental orogenic belt, have been under debate for decades, a key issue being how the convergence has been accommodated at depth. Here we investigate the Moho structure across the central Tien Shan by common-conversion-point imaging and H-k-c stacking of receiver functions from a dense array. The observed Moho exhibits distinct characteristics among sub-blocks. Southward-dipping diffuse Moho is imaged in the Southern Tien Shan (STS), in contrast with the relatively flat and sharp Moho beneath the Tarim Basin. This feature along with the large Moho offset beneath the South-Boundary Fault suggests that the shortening and thickening of Tien Shan crust rather than the underthrusting of the Tarim Basin are responsible for the uplift of the STS. In the Northern Tien Shan, however, the imaged Moho doublet provides direct evidence for the underthrusting of the Kazakh Shield accommodating the convergence there.</p>


2021 ◽  
Author(s):  
Wanderson Luiz-Silva ◽  
Pedro Regoto ◽  
Camila Ferreira de Vasconcellos ◽  
Felipe Bevilaqua Foldes Guimarães ◽  
Katia Cristina Garcia

<p>This research aims to support studies related to the adaptation capacity of the Amazon region to climate change. The Belo Monte Hydroelectric Power Plant (HPP) is in the Xingu River basin, in eastern Amazonia. Deforestation coupled with changes in water bodies that occurred in the drainage area of Belo Monte HPP over the past few decades can significantly influence the hydroclimatic features and, consequently, ecosystems and energy generation in the region. In this context, we analyze the climatology and trends of climate extremes in this area. The climate information comes from daily data in grid points of 0.25° x 0.25° for the period 1980-2013, available in http://careyking.com/data-downloads/. A set of 17 climate extremes indices based on daily data of maximum temperature (TX), minimum temperature (TN), and precipitation (PRCP) was calculated through the RClimDex software, recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI). The Mann-Kendall and the Sen’s Curvature tests are used to assess the statistical significance and the magnitude of the trends, respectively. The drainage area of the Belo Monte HPP is dominated by two climatic types: an equatorial climate in the north-central portion of the basin, with high temperatures and little variation throughout the year (22°C to 32°C), in addition to more frequent precipitation; and a tropical climate in the south-central sector, which experiences slightly more pronounced temperature variations throughout the year (20°C to 33°C) and presents a more defined wet and dry periods. The south-central portion of the basin exhibits the highest temperature extremes, with the highest TX and the lowest TN of the year occurring in this area, both due to the predominant days of clear skies in the austral winter, as to the advance of intense masses of polar air at this period. The diurnal temperature range is lower in the north-central sector when compared to that in the south-central region since the first has greater cloud cover and a higher frequency of precipitation. The largest annual rainfall volumes are concentrated at the north and west sides (more than 1,800 mm) and the precipitation extremes are heterogeneous across the basin. The maximum number of consecutive dry days increases from the north (10 to 20 days) to the south (90 to 100 days). The annual frequency of warm days and nights is increasing significantly in a large part of the basin with a magnitude ranging predominantly from +7 to +19 days/decade. The annual rainfall shows a predominant elevation sign of up to +200 mm/decade only in the northern part of the basin, while the remainder shows a reduction of up to -100 mm/decade. The duration of drought periods increases in the south-central sector of the basin, reaching up to +13 days/decade in some areas. The results of this study will be used in the future as an important input, together with exposure, sensibility, and local adaptation capacity, to design adaptation strategies that are more consistent with local reality and to the needs of local communities.</p>


2020 ◽  
Author(s):  
Endurance Uzobo ◽  
Aboluwaji D. Ayinmoro

Abstract Introduction: Modern Postnatal Care Services (PNC) in Nigeria is vital tool for providing quality health for mothers and newborns. Nonetheless, many regions in Nigeria are still struggling to achieve optimum utilisation of modern PNC services due to variation in associated socioeconomic factors of mothers based on their regions. This study aims at assessing regional socioeconomic factors associated with PNC services utilisation and its relationship with child morbidity in Nigeria. Methods Data for this study was extracted from the Nigeria Demographic and Health Survey (NDHS) 2018 birth recoded file dataset, with a sample size of 30713 women (aged 15–49). Data were analysed using descriptive statistics, Chi-Square Test and logistic regression. The main predictor variable was the region, while others included the type of PNC service utilised and various demographic variables of the respondents – age, education, type of residence, religion, ethnicity among others. Results The average age of the respondents was 29.5 ± 6.8. The use of modern PNC services ranged from South-West (20.3%), South-South (10.9%), South-East (23.0%), North-Central (22.0%), North-East (13.0%) to North-West (10.9%). The prevalence of child morbidity ranged from South-West (8.5%), South-South (9.8%), South-East (11.4%), North-Central (15.3%), North-East (26.3%) to North-West (28.7%). Child morbidity is significantly higher in the South-South (OR = 1.46), South-East (OR = 1.50), North-Central (OR = 1.13), North-East (OR = 2.31) and North-West (OR = 1.35) compared to the South-West. Conclusion Majority of women in Nigeria are not using modern PNC services. Regional variations in the use of PNC services and socio-demographic characteristics of mothers influence child morbidity in Nigeria. There is need for regional-specific context sensitisation for mothers in the use of modern PNC services.


2017 ◽  
Vol 11 (1) ◽  
pp. 54-70 ◽  
Author(s):  
Najib Yusuf ◽  
Daniel Okoh ◽  
Ibrahim Musa ◽  
Samson Adedoja ◽  
Rabia Said

Background: Simultaneous measurements of air temperature were carried out using automatic weather stations at 14 tropical locations in Nigeria. Diurnal variations were derived from the 5-minute update cycle initial data for the years ranging between 2007 and 2013. The temperature trends in Nigeria revealed a continuous variability that is seasonally dependent within any particular year considered. Method: The analysis was carried out using available data from the network and the results are presented with a focus to characterize the temperature variations at different locations in the country using the mean, maximum and minimum temperatures from the north which is arid in nature to the south, which is a tropical monsoon climate type and a coastal region. Result: In overall, temperature variations in Nigeria were observed to have higher values in the far north, attributed to the influence of Sahara Desert, which has less cloud cover and therefore is more transparent to solar irradiance and lowers values in the south, where there are more cloud cover and abundant vegetation. Conclusion: Measured maximum and minimum temperatures in Nigeria are respectively 43.1°C at Yola (north-east part of Nigeria) and 10.2°C for Jos (north-central part of Nigeria). The least temperature variations were recorded for stations in the southern part of the country, while the largest variations were recorded in the north-central region of the country.


1978 ◽  
Vol 68 (4) ◽  
pp. 949-971
Author(s):  
T. G. Rautian ◽  
V. I. Khalturin ◽  
V. G. Martynov ◽  
P. Molnar

abstract This paper reports preliminary results of an analysis of the spectral content of seismic waves from over 1,000 local earthquakes in the Garm, Tadjikistan region. Very low values of Q (∼100) were obtained for the Mesozoic and Cenozoic sedimentary rocks of the Peter I Range compared with those in the crystalline rock of the South Tien Shan (Q ≳ 500). For events with the same low frequency spectra, earthquakes in the South Tien Shan are recorded with more energy at higher frequencies than earthquakes in the Peter I Range, at least in part, because of the greater attenuation of the sedimentary rock in the latter region. There is a wide variety of spectra radiated by earthquakes throughout the Garm region, but a marked difference between spectra radiated by earthquakes from these two regions is not apparent. Nevertheless although calculated stress drops of earthquakes appear to vary considerably throughout the region, there appears to be a dependence on the type of rock in which the earthquakes occurred. The variation in calculated stress drops, however, is greater within either region than between the two. For most regions and for most of the range of seismic moments studied the shape of the spectrum is relatively independent of seismic moment. Consequently, calculated stress drops increase with seismic moment, with the functional dependence varying from region to region. For the largest events, the spectrum shifts to lower frequencies with increasing moment and stress drops become essentially independent of moment. Preliminary results suggest that the stress drops are not detectably different for earthquakes with thrust or normal faulting fault-plane solutions. A limited amount of data are consistent with a change in spectral content and stress drop of earthquakes in the vicinity of and before stronger earthquakes but a clear, consistent pattern is not yet evident. Toward high frequencies, S-wave spectra both begin to decrease at lower frequencies and seem to decrease more rapidly than P-wave spectra, in contrast with predictions of published dislocation models of earthquakes.


2017 ◽  
Vol 27 (5) ◽  
pp. 718-730 ◽  
Author(s):  
David C. Zlesak ◽  
Randy Nelson ◽  
Derald Harp ◽  
Barbara Villarreal ◽  
Nick Howell ◽  
...  

Landscape roses (Rosa sp.) are popular flowering shrubs. Consumers are less willing or able to maintain landscape beds than in years past and require plants that are not only attractive, but well-adapted to regional climatic conditions, soil types, and disease and pest pressures. Marketing and distribution of rose cultivars occurs on a national level; therefore, it is difficult for U.S. consumers in the U.S. Department of Agriculture (USDA) Plant Hardiness Zones 3 to 5 to identify well-adapted, cold-hardy cultivars. Identifying suitable cultivars that have strong genetic resistance to pests and disease and that will tolerate temperature extremes without winter protection in the USDA Plant Hardiness Zones 3 to 5 is of tremendous value to consumers and retailers in northern states. Twenty landscape rose cultivars, primarily developed in north-central North America, were evaluated at five locations in the United States (three in the north-central United States, one in the central United States, and one in the south-central United States) using the low-input, multiyear Earth-Kind® methodology. Six roses had ≥75% plant survival at the end of the study and were in the top 50% of performers for overall mean horticultural rating at each of the three north-central U.S. sites: ‘Lena’, ‘Frontenac’, ‘Ole’, ‘Polar Joy’, ‘Sunrise Sunset’, and ‘Sven’. Five of these six roses met the same criteria at the central United States (exception ‘Lena’) and the south-central United States (exception ‘Polar Joy’) sites. Cultivar, rating time, and their interaction were highly significant, and block effects were not significant for horticultural rating for all single-site analyses of variance. Significant positive correlations were found between sites for flower number, flower diameter, and overall horticultural rating. Significant negative correlations were found between flower number and diameter within each site and also between black spot (Diplocarpon rosae) lesion size from a previous study and overall horticultural rating for three of the five sites. Cane survival ratings were not significantly correlated with overall horticultural rating, suggesting some cultivars can experience severe winter cane dieback, yet recover and perform well. Data from this study benefit multiple stakeholders, including nurseries, landscapers, and consumers, with evidence-based regional cultivar recommendations and breeders desiring to identify regionally adapted parents.


1984 ◽  
Vol 32 (3) ◽  
pp. 263 ◽  
Author(s):  
HW Bramwells ◽  
T Whiffin

Eucalyptus sideroxylon, a woodland tree occumng in an arc from central and southern Victoria to south-eastem Queensland, is currently divided into subsp. slderoxylon to the north, and subsp. tricarpa to the south. Thirty populations were sampled throughout the range of the species and studied for adult leaf and fruit characters. There were found to be very marked and highly significant morphological differences between the two subspecies, more especially in the fruit characters. Within subsp. sideroxylon there was a general distinction between the inland populations and the more coastal populations, while within subsp. trlcarpa there was similarly a general differentiation of the coastal populations from the northern and north-central Victorian populations. The extent and general pattern of these various differences are documented as a prelude to further studies.


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