Trace fossils of precambrian metazoans “Vendobionta” and “Mollusks”

Metazoan trace fossils from the Upper Vendian are preserved together with remains of corresponding organisms. The traces belong to “Vendobionta”, representing the Precambrian phylum Proarticulata and to a presumably trochophoran animal Kimberella quadrata. These organisms fed on microbial mats, which preserved fossil traces. Impressions of the mat surface structures, traces, and bodies of animals are preserved in marine terrigenous sediments on the basal surfaces of sandstone beds. Proarticulata grazing traces are represented by groups and chains of impressions left by the ventral side of a body or its central and posterior parts. Kimberella traces are represented by long ridges united into bundles, fans, and chains of fans. All these traces were largely formed mechanically, i.e., by mat scratching with cilia (Proarticulata) or teeth (Kimberella). Proarticulata representatives destroyed only a thin upper layer of the mat, while Kimberella could possibly scratch the mat through its entire thickness or even tear off pieces from it.     

Comment: A study of “probabilistic” and “deterministic” geostatistics

Stochastic process theory involves integrals of measurable functions over probability measure spaces. One of these is the ensemble space, Ω, whose members are sample functions on Euclidean spaceR ^k and the other isR ^k itself. What geostatisticians call the “theory of regionalized variables” is said to based on stochastic theory. A recent paper inMathematical Geology proclaims a distinction between “probabilistic” and “deterministic” geostatistics. The former is said to rely on “ensemble integrals” over Ω and the latter on “spatial integrals” overR ^k. This study shows that the proposed distinction rests on an arbitrary choice between two estimators for the covariance of a stochastic process; neither is an ensemble integral, both are spatial integrals, and both are Kolmogorov inconsistent. The “deterministic” estimator is identical with that of classical bivariate least-squares regression in which “spatial structure” is of no consequence. This study shows that both stochastic models are suboptimal approximations to the unique nonstationary classical statistical multivariate regression model generated by each sample pattern. The stochastic process model and its “spatial continuity measures,” thus, appear as questionable mathematical embellishments on suboptimal estimates, correspondence with geomorphic reality is tenuous, and estimates are biased and distorted. Various related misconceptions in the paper are also discussed.     

Non-eutectic,graphic, micrographie and graphic-like “myrmekitie” structures and textures

True graphic quartz structures in pegmatites from Carrara/Giggiga and Harrar (town) districts of Ethiopia, are compared with the micrographic quartz textures in the Rapakiwi granite of Finland. Graphic-like textures of uraninite in microcline are also discussed and compared with these graphic structures.A quartz vein, about 1–2 meters in thickness, intersects a pegmatite in the Carrara/Giggiga district. This quartz vein extends into the microcline of the pegmatite as fine quartz veins which attain the form and character of graphic quartz. Also the graphic quartz of the Harrar pegmatites is observed to extend into and occupy cracks in the microcline.Comparable in origin to these graphic textures is the micrographic quartz in the Rapakiwi granite. Observations show micrographic quartz following the cleavage directions in the orthoclase as well as the interzonal spaces and the boundaries of inclusions in the K-feldspar.On the basis of the observed structures and textures these graphic and micrographic intergrowths are considered to be due to solutions penetrating or infiltrating into existing structures and not due to simultaneous crystallisation as conditions of eutectic crystallisation would require.In addition to the well known graphic structures there occur graphic or myrmekitic-like intergrowths of uraninite in microcline which, from a structural and physico-chemical point of view, cannot be considered to be due to eutectic crystallisation.     

IGCP-649 Project “Diamonds and Recycled Mantle”

正The IGCP-649 project"Diamonds and Recycled Mantle"is an International Geosciences Program sponsored by UNESCO and IUGS,supporting the scientific research on ultrahigh pressure and highly reduced minerals in ophiolitic peridotite and chromitite.Ophiolites are 5-to 10-km-thick fragments of ancient ocean lithosphere emplaced on continental margins,and provide3-dimensional exposures to examine the internal structure,     

Some remarks about kinematics “with rotation” and stress-rate

In experiments like simple shear or torsion with the hollow cylinder device, we often talk about kinematics “with rotation”; on the other hand, experiments like compression with a true triaxial apparatus are called “without rotation”. We analyse the difference between these two kinds of kinematics with well known concepts of continuum mechanics. This analysis is conducted in terms of kinematics because the consequences in terms of stress (rotation or no rotation) must be deduced by the use of constitutive relations. In a second part we analyse the stress-rate and we try to give a physical meaning of such an operator. As a conclusion we think that the usual Jaumann derivative is the most meaningful for incremental formulation of constitutive relations.     

Geological and Geochemical Characteristics and Genesis of “Dolomite” at Bayan Obo, China

白云鄂博“白云岩”位于华北板块的北缘,宽沟背斜的南翼.蕴藏着世界最大的稀土矿床,还是大型—超大型铌、铁和钍等矿床赋存母岩.“白云岩”不是层状岩石,无明显的层理和固定的层位,而是一套大小不等,串珠状的”白云岩”带.“白云岩”与围岩呈明显的侵入关系.表现在“白云岩”切割H4石英砂岩、H5板岩和花岗岩脉,并有许多分枝脉插入到H4石英砂岩和H5板岩中.“白云岩”中存在H4石英砂岩的残留顶盖相,捕获了H4石英砂岩和H5板岩的捕掳体,并引起围岩的强烈蚀变.板岩的黑云化,石英砂岩的钠闪石化,花岗岩的碱交代.“白云岩”含有大量铌、稀土、钍等岩浆岩中常见的矿物晶体.硫、碳、氧、锶和铁等同位素组成都具有深源特征.说明白云鄂博“白云岩”不是沉积岩,而是岩浆碳酸岩.     

“Metamorphic Processes and Geodynamics”英文专辑征稿通知

正尊敬的各位同仁:2018年金秋九月是我国著名岩石学家游振东教授的90华诞.游振东教授1952年毕业于北京大学地质学系,1956年起一直在中国地质大学(包括其前身原北京地质学院、武汉地质学院)从事岩石学的教学与科研工作,为我国变质岩石学学科的发展和人才培养做出了突出贡献,荣获李四光地球科学奖(教学奖)、原国家教委(现教育部前身)教学成果国家级一等奖和全国教育系统劳动模范称号.游振东教授是我国变质地质学的奠基人之一.他在20世纪80年代即敏锐地注意到国际上变质作用研     

Migmatization and “secondary” granitic magmas: effects of emplacement and crystallization of “primary” granitoids in Southern Bohemia,Austria

The Sauwald and Mühl zones of the prebatholithic, Moldanubian, middle crust in northern Austria contain metapelites and metaluminous to weakly peraluminous metagreywackes, respectively. Both zones were affected by low-pressure, high-temperature metamorphism and anatexis. The metapelites of the Sauwald zone became in-situ diatexites, probably by fluid-absent reactions involving the breakdown of muscovite and the partial breakdown of biotite. The biotite-plagioclase-quartz gneisses of the Mühl zone experienced only slight melting. Following this event, and while the mid crust was still hot, additional heat was locally advected into the Mühl zone by the intrusion of the Weinsberg granite. This brought about fluid-present partial melting of the biotite-plagioclasequartz gneisses, producing relatively large volumes of metaluminous to weakly peraluminous, I-type Schlieren granite. This cool, wet, restite-rich magma remained close to its site of generation. Thus, infracrustal I-type granitoids may be formed anywhere in the crust, and not always at high T. Under special circumstances the heat and fluids from granitic magmas can spawn secondary granites. Also, relatively low initial ⁸⁷Sr/⁸⁶Sr values (of around 0.707) in I-type rocks do not necessarily indicate either lower crustal magma sources or mixing with mantle-derived magma. The Weinsberg granite magma came from the lower crust (P probably <700 MPa), where widespread fluid-absent breakdown of biotite-plagioclase-quartz assemblages occurred. The necessary high heat flow was probably provided by newly underplated mafic magmas. However, these seem not to have mixed or mingled with the crustally derived Weinsberg magmas. Deep equivalents of the Mühl-zone metagreywackes may have formed the Weinsberg protolith. Fluid-absent experiments show that the melting temperature probably exceeded 850°C and that a garnet-bearing, orthopyroxene-rich residue should be present in the lower crust. Fluid-present experiments demonstrate that the availability of free H₂O can radically alter the characteristics of the partial melts, from apparent S-type mineralogy (with fluid-absent melting) to I-type mineralogy (with wet melting).     

Working towards conceptual consistency in discussing “diaspora” and “diaspora strategies”: Ethnicity and affinity in the case of Japan

The terms “diaspora” and “diaspora strategies” are both used in inconsistent, and often, conflicting ways. Who encompasses “the diaspora” and what are “diaspora strategies”? What roles do ethnicity and affinity play in conceptualizing relationships between diasporas and homeland governments? This paper extrapolates from programs and organizations that link overseas coethnic and former resident non-coethnic populations to Japan to offer clarity and consistency in usage by bringing together concepts not typically put in conversation with each other and introducing new terms that conceptualize more specific aspects of who we are referring to as “diaspora” and what we are referring to as “diaspora strategies”. Conceptualizations of diaspora often gloss over internal differences, including whether or not people deemed members of a diaspora actually demonstrate a homeland orientation. Focusing on the difference between ethnicity-based and affinity-based definitions of diaspora, I distinguish between three types of diaspora strategies: “diaspora-connecting”, “diaspora-cultivating”, and “diaspora-creating strategies”. Finally, as a way to discuss the potential contributions of both overseas coethnic and non-coethnic populations to a given nation, I conclude by considering Joseph Nye’s notion of “soft power” in relation to diaspora strategies. By engaging these concepts together, the paper highlights the tensions between considering ethnicity and affinity as factors for deciding who to target for diaspora strategies, and demonstrates how diaspora strategies can also target non-coethnics.     

IGU Study group “famine research and food production systems”

IGU-Reports

IGU Study group famine research and food production systems     

IGU study group “Famine research and food production systems”

The International Geographical Union Reports

IGU study group Famine research and food production systemsIn collaboration with the IGU study group critical environmental regions/places     

“Exact” Frequency-Dependent Rays in Acoustic Media and Their Properties

Doklady Earth Sciences - The numerical algorithm for tracing “exact” frequency-dependent rays, which makes it possible to trace these rays in arbitrary media is proposed. In addition, a...     

“Ultrahigh-temperature” metamorphism and titaniQ: Examples from eastern Siberia

Titanium contents of quartz have been analyzed in samples of granulites from various metamorphic complexes of eastern Siberia (Sutam, Chogar, and Sharyzhalgai) that contain mineral assemblages conventionally regarded as indicative of “ultrahigh-temperature” metamorphism. The related TitaniQ temperature estimates (Wark and Watson, 2006) are consistent with those of other mineralogical geothermometers and are commonly much lower than “ultrahigh-temperature”.     

“Glossary of Permafrost and Related Ground—Ice Terms”

1982年10月,加拿大全国研究协会土工研究委员会多年冻土分会决定,在由已故的R.J.EBrown和W.O.Kupsch和编的1974年出版的“多年冻土名词术语”(Permafrost Terminology)的基础上重新编制一本与多所冻土和地下冰有关的术语。翌年,该分会建立了一个专门的工作组来从事这项工作。经过三年的努力,该书于1986年正式出版。     

“Glossary of Permafrost and Related Ground—Ice Terms”

1982年10月,加拿大全国研究协会土工研究委员会多年冻土分会决定,在由已故的R.J.EBrown和W.O.Kupsch和编的1974年出版的“多年冻土名词术语”(Permafrost Terminology)的基础上重新编制一本与多所冻土和地下冰有关的术语。翌年,该分会建立了一个专门的工作组来从事这项工作。经过三年的努力,该书于1986年正式出版。     

Water Security and the Countermeasures in South Asia Based on the “Belt and Road” Initiative

South Asia is the subregion of Asia with the most neighbors of China. Although the high mountains in the Great Himalayas spatially separate South Asia from East Asia along the border of China’s autonomous region of Tibet, the geographical items such as mountains and rivers link the countries in South Asia with China, resulting in a special and complex geopolitical environment and relationship. In this geopolitical relationship, the transboundary rivers are becoming a key issue of this region in an era of increasing water stress. Depleted and degraded transboundary water supplies have the potential to cause social unrest and spark conflict within and between countries in South Asia, and complicate the geopolitical relationship among them. In addition, the increasing impacts from climate change and human activities will definitely bring many transboundary eco-environmental issues in this region, projecting a big challenge to regional stability and development. The key issues related to the water resources supplement and exploration require the transboundary rivers to be a positive role in regional water resources utility and exploration, and the result will definitely affect regional relationship and water security. How to handle these issues and challenges will be a question for the countries in this region with a long time. Currently, the “Belt and Road” Initiative represents an opportunity to build a shared vision for common prosperity through regional cooperation and is a way to inject new positive energy into world peace and development. In the light of this, the countries with transboundary rivers in South Asia must come together to construct a cooperative mechanism of water security, and adopt a win-win cooperation for the use of transboundary rivers under the principles of “equal”, “equitable” and “reasonable”.     

“In situ” visualization of phase states and transformations of hydrocarbons in water-oil mixtures at high and ultrahigh temperatures and pressures

Doklady Earth Sciences -