Internal waves in the near-bottom thermocline and microdeformations in the Earth’s crust in the continent-ocean transition zone

The results of synchronous measurements of temperature variations in a near-bottom thermocline, as well as microdeformations of the Earth’s crust and atmospheric pressure pulsing, recorded on-shore with the help of a laser strainmeter and laser nanobarograph, are presented. A string containing 20 thermosensors spaced at 0.5 m was used; it was placed by an anchored buoy in a place with 21-m depth and 500 m away from the shore. A good correlation between microdeformations and atmospheric pressure variations was observed for periods longer than 6 h. Quantitative estimates and spectral analysis via the Gilbert-Huang method for investigation of nonstationary and nonlinear processes lead to the conclusion that, on temporal scales from tidal to several minutes, the predominant way of formation of microdeformations in the Earth’s crust can be breaking of internal waves in a thermocline that leads to shallow water (i.e., in the zone of “internal breakers”).     

Changes in the Abundance and Species Composition of Phytoplankton in the Last 150 Years in the Southern Black Sea

Changes in total abundance and in species composition of phytoplankton in the last 150 years in the southern Black Sea were investigated through a paleoecological study of two sediment cores. The results show changes in the species composition and a marked increase in total abundance of siliceous protists after around 1960. In core 22 (42°13.534′ N/36°29.555′ E), the dominating species before 1960 were Cyclotella choctawhatcheeana and Thalassiosira oestrupii. In core 25 (42°6.212′ N/36°37.460′ E), the dominating species before 1960 were T. oestrupii, Cyclotella meneghiniana, C. choctawhatcheeana, and Pseudosolenia cf. calcar-avis. Core 22 was located in closer proximity to the rim current than core 25, and the differences in total abundance between the cores could be related to differences in local nutrient loading prior to 1960. After around 1960, both cores changed to a community dominated by C. choctawhatcheeana. The changes in total abundance and species composition after around 1960 could be related to the increased nutrient loading from the Danube River into the rim current after the late 1960s. The results also showed changes in both total abundance and in species composition of dinoflagellate cysts. The dominating dinoflagellate cysts recorded were Lingulodinium polyedrum, Polykrikos schwartzii, and Spiniferites spp.     

Mercury pollution in the atmosphere-soil-biology ecosystem along the trunk road in Guilin

Based on the mercury distribution in soil, atmosphere and plant in seven sections beside the trunk road, some advances are obtained： （1） Mercury content of fuel oil of petrol station in Guilin is 3.66-9.74 ng/g, higher than that reported by other countries （0.7-3.2 ng/g）. The higher the number of petrol, the lower the content. Number 90 petrol widely used is the highest （9.74 ng/g）. （2） Mercury content in soil is commonly 0.30-0.80 μg/g near the road, （0.30-2.60 μg/g） besides the street, both are higher than the average of Guilin background value （0.204 μg/g）. Mercury content in vegetable near the road is generally 0.025-0.055 μg/g, higher than that far away from the road （0.022-0.038 μg/g）. The content in cinnamon leaves on both sides of the street is 0.06-0.16 μg/g, also higher than that far away from the street （0.051-0.067 μg/g）. Guilin Highway atmospheric mercury content is usually 7-12 ng/m^3, higher than the mean background value （4.4-6.6 ng/m^3）. Atmospheric mercury content near rural roads is below the level on urban roads. The atmospheric mercury content increases apparently in traffic-intensive stations and intersections. （3） The average concentration of mercury in vegetables is mostly 0.025-0.055 μg/g. Mercury content in various tissues of vegetable follows the order of leaves （mostly 0.044）.09 μg/g）〉roots （mostly 0.02-0.05 lag/g）〉stems （mostly 0.01-0.04 μg/g）. （4） The distribution of mercury in soil, plants and atmosphere near the road is of certain similarity, with a single peak, nearly symmetrical. As far away from road, the content reduces gradually, which shows the release of exhaust gas mercury is the main source of atmospheric mercury pollution.     

Change in the Geodynamic Settings in the Pacific‒Eurasia Transition Zone at the End of the Early Cretaceous

Doklady Earth Sciences - An attempt to provide a new explanation for the change in the geodynamic regime in the Early Cretaceous is presented below. It accounts for data on a number of global...     

Fluctuations in the angular momentum of the atmosphere and intraday irregularities in the Earth’s rotation

Numerical celestial-mechanical models are used to compare (andg interpolate and forecast) near-diurnal tidal variations in the Earth’s axial rotation and oscillations in the global angular momentum of the atmosphere using the IERS data and NCEP/NCAR meteorological data. In order to improve the accuracy of interpolations and forecasts made for short and intraday time intervals, it is expedient to include the effect of small perturbations in short-term zonal tides, which influence fluctuations in Universal Time UT1 directly related to the Earth’s rotation. Due to the quasi-static formulation of the problem, it is assumed that the dynamics of the thin surface atmosphere are completely determined by the gradient of the tide-generating geopotential, which supports forced oscillations of the entire subsystem (i.e., of the mantle and atmospheric envelope). A comparison of the numerical simulations with the NCEP/NCAR data shows that the model is effective for applications in forecasting atmospheric tides.     

The Orogeny in the Altaides

Studies of the deformation styles, formation types and isotopic age data indicate that the Altaides has successively experienced 5 stages of orogeny: (1) the Kanas orogeny forming the angular unconformity between the Baihaba Formation (O_3) and the Habahe Group (Z-O_2); (2) the Daqiao orogeny (S_3-D_(1-2) giving rise to the early Hercynian quasi-aulacogen extensional continental crust of the area; (3) the Altay orogeny (middle-late Hercynian) leading to the oblique intracontinentai collision and the formation of large shear arc-shaped thrust system and representing a strong orogeny stage; (4) the pan-Altay orogeny (latest Hercynian-Indosinian) resulting in the uplifting and erosion of the mountains as a whole; (5) the Himalayan movement causing the rejuvenation of fault systems and block uplift of the Aitaides since the Cenozoic.     

Sedimentary Characteristics of the Cretaceous in the Songliao Basin

The rupture of the lithosphere in Late Jurassic brought about the eruption of basaltic magma in the Songliao Basin. The evolution of the basin in Cretaceous progressed through six stages: pre-rift doming, extensional fracturing, fault subsidence, fault downwarping, downwarping and shringkage, resulting in the deposition of terrstrial facies nearly 10,000 m thick. There are different depositional sequences in these stages: the depositional period of the Early Cretaceous Shahezi and Yincheng Formations is the development stage of the down-faulted basin, forming a volcanic rock-alluvial fan-fan delta-lacustrine (intercalated with episodic turbidites)-swamp facies sequences; the period of the Early Cretaceous Dengluku Formation is the transformation stage of fault subsidence into fault downwarping of the basin, forming a sequence mainly of alluvial plain-lacustrine facies; the depositional period of the Early Cretaceous Quantou Formation-Late Cretaceous Nenjiang Formation is the downwarping stage of the basin, forming an alluvial plain-delta-lacustrine facies sequence; the period of the Late Cretaceous Sifangtai Formation-Mingshui Formation is the shringkage stage of the basin, forming again a sequence mainly of alluvial plain-alluvial fan and small relict lacustrine facies. These vertical depositional sequences fully display the sedimentary characteristics of a failed continental rift basin. Many facts indicate that the two large-scale lake invasions, synchronous with the global rise of sea level, which took place in the downwarping stage of the basin development, led to the connection between the lake and sea.     

Magnetostratieraphy of the Red Beds in the Hengyang Basin

This paper discusses the Cretaceous-Tertiary magnetic polarity sequence of the the Hengyang Basin on the basis of magnetostratigraphic study. The age of each stratigraphic unit has been determined with the magnetic polarity time scale combined with 39Ar/40Ar dating, thus providing evidence for determining the geological ages of different formations. The authors assign the age of the Dongjing Formation of the Hengyang Basin to Early Cretaceous, the Shenhuangshan Formation to Early-Late Cretaceous, the Daijiaping Formation to Late Cretaceous, and the Dongtang and Xialiushi formations to Palaeocene.     

Analysis on the sources of mercury in soils in the Chengdu Basin, China

Mercury is a pollutant of concern due to its toxic and bioaccumulative properties. Studies on the distribution and hazard of mercury in the environment are mainly focused on its forms, toxicity and the environment standard, and progresses and results have been achieved. But these studies in the past were concentrated on the scales of laboratory or smaller districts merely, such as a small unit of mineral area, vegetable base, paddy field, lake, etc. Multi-target regional geochemical survey carried out by China Geological Survey from the 1990s to now is a fundamental and commonweal geological survey, large-scale and systematical inquisition and research were conducted in 19 provinces （or municipalities directly under the Central Government） in the eastern overlay region of China, and the purpose is to provide the basic geochemical data for national economic construction, adjustment of industrial and agricultural structures and sustainable social development. Geochemical studies aim at investigating soils in these regions and 52 elements have been tested, producing a great amount of data at the same time. Methods： based on the data from 3061 samples of surface soil and 832 samples of deep soil from the project of multi-purpose geochemical survey in the Chengdu Basin, Sichuan, China, this paper describes the correlation relationship between Hg and other 48 elements and their spatial distribution in surface and deep soils of these areas by applying the method of linear regression and factor analysis.     

Gas–oil fluids in the formation of travertines in the Baikal rift zone

Active participation of gas–oil fluids in the processes of mineral formation and petrogenesis in travertines of the Arshan and Garga hot springs is substantiated. The parageneses of the products of pyrolytic decomposition and oxidation of the gas–oil components of hydrothermal fluids (amorphous bitumen, graphite-like CM, and graphite) with different genetic groups of minerals crystallized in a wide range of P–T conditions were established. Travertines of the Baikal rift zone were formed from multicomponent hydrous–gas–oil fluids by the following basic mechanisms of mineral formation: chemogenic, biogenic, cavitation, fluid pyrometamorphism, and pyrolysis.     

Progress of machine learning in geosciences: Preface

正In the past two decades,artificial intelligence(AI)algorithms have proved to be promising tools for solving several tough scientific problems.As a broad subfield of AI,machine learning is concerned with algorithms and techniques that allow computers to"learn".The machine learning approach covers main domains such as data mining,difficult-to-program applications,and software applications.It is a collection of a variety of algorithms that     

http://www.sciencedirect.com/science/article/pii/S1674987115000973

Tarim Precambrian bedrocks are well exposed in the Kuluketage and Aksu areas,where twenty four samples were taken to reveal the denudation history of the northern Tarim Craton.Apatite fission track dating and thermal history modeling suggest that the northern Tarim experienced multi-stage cooling events which were assumed to be associated with the distant effects of the Cimmerian orogeny and India-Eurasia collision in the past.But the first episode of exhumation in the northern Tarim,occurring in the mid-Permian to Triassic,is here suggested to be induced by docking of the Tarim Craton and final amalgamation of the Central Asian Orogenic Belt.The cooling event at ca.170 Ma may be triggered by the Qiangtang-Eurasia collision.Widespread Cretaceous exhumation could be linked with docking of the Lhasa terrane in the late Jurassic.Cenozoic reheating and recooling likely occurred because of the northpropagating stress,however,this has not affected the northern Tarim much because the Tarim is characterized by rigid block-like motion.     

http://www.sciencedirect.com/science/article/pii/S1674987115000869

The predictability of dangerous atmospheric phenomena such as tornado outbreaks has generally been limited to a week or less. However, recent work has demonstrated the importance of the Rossby wavetrain phasing over the United States in establishing outbreak-favorable environments. The predictability of Rossby wavetrain phasing is strongly related to numerous climate-scale interannual variability indices, which are predictable many months in advance. To formalize the relationship between interannual variability indices and seasonal tornado outbreak frequency, indices derived from monthly mean Northern Hemisphere 500-hPa and 1000-hPa geopotential height fields and Ni?o 3.4 indices for ENSO phase were compared to annual tornado outbreak seasonal frequencies. Statistical models predicting seasonal outbreak frequency were established using linear(stepwise multivariate linear regressione SMLR) and nonlinear(support vector regressione SVR) statistical modeling techniques.The stepwise methodology revealed predictors that are important in establishing outbreak-favorable environments at long lead times. Additionally, the results of the statistical modeling revealed that the nonlinear SVR technique reduced root mean square errors produced by the control SMLR technique by 28% and provided more consistent forecasts. A preliminary physical analysis revealed that years with high outbreak frequencies were associated with the presence of 500-mb troughs over the central and western US during the peak of outbreak season, while lower frequencies were consistent with ridging over the US or northwest flow over the Plains. These patterns support the results of the statistical modeling, which demonstrate the utility of geopotential height variability as a predictability measure of outbreak frequency.     

http://www.sciencedirect.com/science/article/pii/S1674987115000596

Seafloor polymetallic sulfide resources exhibit significant development potential.In 2011,China received the exploration rights for 10,000 km~2 of a polymetallic sulfides area in the Southwest Indian Ocean;China will be permitted to retain only 25%of the area in 2021.However,an exploration of seafloor hydrothermal sulfide deposits in China remains in the initial stage.According to the quantitative prediction theory and the exploration status of seafloor sulfides,this paper systematically proposes a quantitative prediction evaluation process of oceanic polymetallic sulfide resources and divides it into three stages:prediction in a large area,prediction in the prospecting region,and the verification and evaluation of targets.The first two stages of the prediction process have been employed in seafloor sulfides prospecting of the Chinese contract area.The results of stage one suggest that the Chinese contract area is located in the high posterior probability area,which indicates good prospecting potential area in the Indian Ocean.In stage two,the Chinese contract area of 48°-52° E has the highest posterior probability value,which can be selected as the reserved region for additional exploration.In stage three,the method of numerical simulation is employed to reproduce the ore-forming process of sulfides to verify the accuracy of the reserved targets obtained from the three-stage prediction.By narrowing the exploration area and gradually improving the exploration accuracy,the prediction will provide a basis for the exploration and exploitation of seafloor polymetallic sulfide resources.     

http://www.sciencedirect.com/science/article/pii/S1674987115300050

The intense study of coleopteran inclusions from Spanish(Albian in age) and French(Albian-Santonian in age) Cretaceous ambers,both of Laurasian origin,has revealed that the majority of samples belong to the Polyphaga suborder and,in contrast to the case of the compression fossils,only one family of Archostemata,one of Adephaga,and no Myxophaga suborders are represented.A total of 30 families from Spain and 16 families from France have been identified(with almost twice bioinclusions identified in Spain than in France);13 of these families have their most ancient representatives within these ambers.A similar study had previously only been performed on Lebanese ambers(Barremian in age and Gondwanan in origin),recording 36 coleopteran families.Few lists of taxa were available for Myanmar(Burmese) amber(early Cenomanian in age and Laurasian in origin).Coleopteran families found in Cretaceous ambers share with their modern relatives mainly saproxylic and detritivorous habits in the larval or adult stages,rather than wood-boring behavior.Fifteen of the coleopteran families occur in both the Lebanese and Spanish ambers;while only five are present in both Spanish and French.Considering the paleogeographic proximity and similarity of age of the Spanish and French ambers,the small number of taxa found in common at both areas is surprising.The ancient origin for the Lebanese and Spanish ambers,the paleogeography(including some barriers for terrestrial biota) and the local paleohabitats are factors that may explain the dissimilarity with the French specimens.Wildfires are believed to be a more likely cause of resin production during the Cretaceous than infestation by beetles.Current knowledge of the beetle species found in the Cretaceous ambers is introduced.     

The Mesoproterozoic to early Neoproterozoic passive margin Lajeado Group and Apiaí Gabbro,Southeastern Brazil

The Lajeado Group in the Ribeira Belt,southeastern Brazil,corresponds to an open-sea carbonate platform,comprised of seven overlapping siliciclastic and carbonatic formations,intruded in its upper portion by the Apiai Gabbro.These rocks have a Neoproterozoic tectonometamorphic overprint related to arc magmatism and the Brasiliano collisional orogeny.Geochronological constraints are given by new UPb SHRIMP and LA-ICP-MS data for Lajeado Group detrital zircons and for magmatic zircons from the Apiai Gabbro.The youngest detrital zircons in the Lajeado Group are 1400-1200 Ma,and constrain its maximum age of deposition to be 1200 Ma,whereas the 877 ± 8 Ma age for magmatic zircons in the Apiai Gabbro give the minimum age.Detritus source areas are mainly Paleoproterozoic(2200-1800 Ma)with some Archean and Mesoproterozoic contribution(1500-1200 Ma),with distal or tectonic stable cratonic character.The Lajeado Group should be a Stenian-Tonian carbonate platform passive margin of a continent at this time,namely the Columbia/Nuna or the Rodinia.The Apiai Gabbro displays similar age to other intrusive basic rocks in the Lajeado and Itaiacoca groups and represents tholeiitic MORB-like magmatism that we relate to the initial break-up of a Mesoproterozoic continent and the formation of the Brasiliano oceans.     

http://www.sciencedirect.com/science/article/pii/S1674987115000882

A detailed vibrational Raman-IR spectroscopic and diffractional analyses have been performed on basalts from two locations from Tenerife Island:(1) the Arenas Negras volcano which belongs to the historical eruption not showing visible alteration and(2) Pillow Lavas zone from Anaga Massif which shows a clearly fluid-rock interaction caused by submarine alteration.These places have been extensively studied due to its similarity with the surface of Mars.The analysis is based on the mineral detection of selected samples by a Micro-Raman study of the materials.The complementary techniques have confirmed the mineralogy detected by the Raman measurement.The results show a volcanic environment behavior with primary phases like olivine,pyroxene,and feldspar/plagioclase.Moreover,the presence of accessory minerals or secondary mineralization like phosphate,iron oxides,zeolite or carbonates shows the alteration processes on each outcrop.The variation in the crystallinity and amorphous phases is related to fluid-rock interaction caused by hydrothermal episodes and external weathering processes,which shows several analogies with the ancient volcanic activity from Mars.     

http://www.sciencedirect.com/science/article/pii/S1674987115000894

In the present paper lignites from the Cambay basin have been studied for their hydrocarbon potential.The samples were collected from three lignite fieldse Vastan, Rajpardi and Tadkeshwar, and were investigated by petrography, chemical analyses and Rock-Eval pyrolysis. The results are well comparable with the empirically derived values. The study reveals that these ‘low rank C' lignites are exceedingly rich in reactive macerals(huminite t liptinite) while inertinite occurs in low concentration. These high volatile lignites generally have low ash yield except in few sections. The Rock-Eval data indicates the dominance of kerogen type-III with a little bit of type-II. The study reveals that the lignites of Vastan(lower and upper seams) and Tadkeshwar upper seam are more gas-prone while Rajpardi and Tadkeshwar lower seams are oil-prone. Further, the fixed hydrocarbons are several times higher than the free hydrocarbons. The relation between TOC and fixed hydrocarbon indicates that these lignites are excellent source rock for hydrocarbon which could be obtained mainly through thermal cracking. The empirically derived values reveal a high conversion(94e96%) and high oil yield(64e66%) for these lignites.     

http://www.sciencedirect.com/science/article/pii/S1674987116300342

U-Pb analyses were carried out on detrital zircon grains from major river-mouth sediments draining South Korea to infer provenance characteristics and the crustal growth history of the southern Korean Peninsula, using a laser ablation inductively coupled plasma mass spectrometer(LA-ICP-MS). The Korean Peninsula is located in the East Asian continental margin and mainly comprises three Precambrian massifs and two metamorphic belts in between them. We obtained 515 concordant to slightly discordant zircon ages ranging from ca. 3566 to ca. 48 Ma. Regardless of river-mouth location, predominance of Mesozoic(249e79 Ma) and Paleoproterozoic(2491e1691 Ma) ages with subordinate Archean ages indicates that the zircon ages reflect present exposures of plutonic/metamorphic rocks in the drainage basins of the South Korean rivers and the crustal growth of the southern Korean Peninsula was focused in these two periods. Comparison of detrital zircon-age data between the North and South Korean river sediments reveals that the Paleoproterozoic zircon age distributions of both regions are nearly identical,while the Neoproterozoice Paleozoic ages exist and the Mesozoic ages are dominant in southern Korean Peninsula. This result suggests that Precambrian terrains in Korea record the similar pre-Mesozoic magmatic history and that the influence of Mesozoic magmatism was mainly focused in South Korea.     

http://www.sciencedirect.com/science/article/pii/S1674987115001516

The Semail ophiolite of Oman and the United Arab Emirates(UAE) provides the best preserved large slice of oceanic lithosphere exposed on the continental crust,and offers unique opportunities to study processes of ocean crust formation,subduction initiation and obduction.Metamorphic rocks exposed in the eastern UAE have traditionally been interpreted as a metamorphic sole to the Semail ophiolite.However,there has been some debate over the possibility that the exposures contain components of older Arabian continental crust.To help answer this question,presented here are new zircon and rutile U-Pb geochronological data from various units of the metamorphic rocks.Zircon was absent in most samples.Those that yielded zircon and rutile provide dominant single age populations that are 95-93 Ma,partially overlapping with the known age of oceanic crust formation(96.5-94.5 Ma),and partially overlapping with cooling ages of the metamorphic rocks(95-90 Ma).The data are interpreted as dating high-grade metamorphism during subduction burial of the sediments into hot mantle lithosphere,and rapid cooling during their subsequent exhumation.A few discordant zircon ages,interpreted as late Neoproterozoic and younger,represent minor detrital input from the continent.No evidence is found in favour of the existence of older Arabian continental crust within the metamorphic rocks of the UAE.