Petrographic and Geochemical Characteristics of the Pouni Palaeoproterozoic Formations North of the Léo Square Degree (Burkina Faso, West Africa)

The Pouni area is made up of basalts belonging to the Boromo belt, lamprophyres and granitoids. These geological formations are similar to geological formations of the same type in other regions of the Palaeoproterozoic domain of the Man/Leo shield. This study, which focused on the petrographic and geochemical characteristics of these geological formations, led to the following main conclusions: The lamprophyres are basic plutonic rocks that cut through other geological formations. The basalt belongs to the northern part of the Borormo belt and is thought to be a relic of overthickened oceanic plateaus. There are two groups of granitoid rocks. The granodiorite has a geochemical signature close to that of Archean TTGs and is metaluminous in character. It has a low potassium content. The minor element and rare earth element spectra indicate that it could be derived from partial melting of basic magmatic rocks. Biotite granites are peraluminous and highly potassic. Minor element contents and rare earth spectra indicate that they could be derived from partial melting of felsic materials. Geotectonic diagrams show that the granitoids identified in the Pouni zone were emplaced in an active tectonic context, similar to that of present-day subduction zones.

Petrographic and Geochemical Characteristics of the Granitoids in the South of Godé (North of the Square Degree of Léo-Burkina Faso, West Africa)

South of Godé, in the central-western region of Burkina Faso, granitoids of Paleoproterozoic age are similar to those of the Man/Leo shield. This study focused on the petrographic and geochemical characteristics of these granitoids, with the following results: 1) The tonalite that outcrops in the south-west of the study area belongs to the TTG group or first generation granitoids. They are most often ribboned at outcrop and have a geochemical signature close to that of Archean TTGs. Tonalite has a metaluminous character and the REE spectrum indicates that it may be derived from partial melting of basic magmatic rocks. 2) Biotite granites have no outcrop structure. They are weakly metaluminous to peraluminous and potassic to highly potassic. Their rare earth spectra indicate that they may be derived from the partial melting of TTG granitoids. 3) Geotectonic diagrams show that the granitoids studied to the south of Godé were emplaced in an active tectonic context similar to that of present-day subduction zones.

Major Characteristics of the Lajishan Orogenic Belt of the South Qilian Mountains and Its Geotectonic Attribute

The Lajishan orogenic belt is one of the E-W-trending Caledonian orogenicbelts within the Qinling-Qilian orogenic system. It was formed upon the Jiningian basement byintensive taphrogenesis. Its major characteristics comprise the prominent faulting along the northand south boundaries, the highly complicated petrological and petro-geochemical features of thevolcanic rock series, and the development of a new type of ophiolite suite. In terms of tectonicanalysis and the sequential analysis of tectonic settings of magmatic rocks, it is suggested thatthe Lajishan orogenic belt has undergone a complete 'opening-closing' cycle, which can be furtherdivided into 3 second-order 'opening-closing' cycles. The composite characteristics of the'opening-closing' movement show that Laji Mountain is a typical fault orogenic belt. The faultorogenic belt is one of the most important types of intracontinental orogens. It is of criticaltheoretical and practical significance to summarize the characteristics and the diagnostic criteriaof this kind of orogenic belts, and study the mechanism of their formation and build models of theirevolution.

On the Geotectonics of Southern China

The tectonic nature of southern China has changed again and again in the Phanerozoic. In the Caledoniancycle, there existed three tectonic units——the Yangtze paraplatform, Indosinian-South China Sea paraplatformand Caledonian South China fold belt, of which the last unit is not a collisional orogenic belt but ascissor-shaped aulacogen-type geosyncline opening towards Yunnan and Vietnam. In the Indosinian cycle,South China belonged to the Tethyan tectonic domain, and no abyssal oceanic basin existed there. Since theLate Triassic, especially in the Yanshanian orogenic stage, it became a component part of the peri-Pacificcontinental-margin activation belt of eastern Asia. No Alpinc-type orogenic belt occurs in the interior of thecontinent of southern China.

Nonlinear wave mechanisms of very fast chemical and phase transformations in solids. applications to cosmic chemistry processes near to 0 k, to explosive-like decays of metastable solid phases and to catastrophic geotectonic phenomena

In the Universe, chemical reactions occur at very low temperature, very close to 0K. According to the standard Arrhenius mechanism, these reactions should occur with vanishingly small efficiency. However, cold planets of the solar system, such as Pluto, are covered by a crust composed of ammonia and methane, produced on earth only at very high temperature and pressure, in the presence of catalysts. This observation is incompatible with the predictions of Arrhenius kinetics. Here, we propose a general mechanism to explain the abundance of chemical reactions at very low temperature in the Universe. We postulate that the feedback between mechanical stress and chemical reaction provides, through fracture propagation, the energy necessary to overcome the activation barrier in the absence of thermal fluctuations. The notion described in this work can also be applied to other fields such as explosive-like solid phase transformations and catastrophical geotectonics phenomena (earthquakes).

AN ANALYSIS OF THE GEOTECTONICCONDITIONS OF FORMATION OF NONMETALLIC ORES ON THE WESTERN MARGIN OF THE DONGTING DIWA

There is a close relationship between occurrence of nonmetallic minerals and tectonic evolution of geosyncline, platform and diwa (geodepression) on the western margin of the Dongting diwa. Some results that (1) diwa tectonics is berfeficial for formation and preservation of nonmetallic minerals and (2) volcano-sedimentary altered ore deposits, saline deposits and organo-sedimentary ore deposits can be often found in diwa basins are gained.

GEOLOGICAL FORMATIONS AND GEOTECTONIC DEVELOPMENT OF SARAWAK AND SABAH, EAST MALAYSIA

Sarawak and Sabah forms part of the continental margin extending belt of Southeast Asia.Based on the discussion of sedimentary, magmatic and metamorphic formations resulting from geotectonic development from the Paleozoic to the Cenozoic. this area may be subdivided into two different tectonic regions. Geotectonic development and evolution of the regional crust are subsequently discussed in the paper.

Amur Gold-Bearing Belt: Geotectonic Position and Perspectives for Revealing New Deposits of Precious Metals

The ore-bearing belts, specialized for precious metals, are substantia ted to exist in the south Far East of Russia. The longest of which is the Amursk y gold-bearing belt extended from the Amur River mouth to the Ussuri River lowe r course and further to the southwest on China territory, probably, to the Sungar i River head. The fact that we have distinguished the Amursky and other gold-be a ring belts, make it possible to reevaluate the perspectives of the South Far Eas t of Russia and North-East China for new deposits of precious metals.

GEOTECTONIC OF NAMCHE BARWA SYNTAXIS IN EAST TIBET, CHINA

Eastern Himalayan Syntaxis consists of Namche Barwa and Assam syntaxis. Namche Barwa, located at south east edge Tibet plateau, is the least\|known place for geologist, because there are thick trees and more rains as well as difficult traffic condition, but Namche Barwa syntaxis is very important to Himalayan and Tibet plateau research. A Big Bend of Yalu Tsangpo and the deepest Grand Canyon in the word developed in Namche Barwa region. From core to surrounding Namche Barwa syntaxis may be divided into Himalayan,Yalu Tsangpo as well as Gangdise three tectonic units and three boundary fault zone.The core of syntaxis is Himalayan unit with Zircon U\|Pb age 1312±6Ma which is correlated to High Himalayan unit in central Himalayan, major rocks of core are garnet\|plagioclase gneiss and hornblende\|plagioclase gneiss as well as layered migmatites, some lens or band of high pressure granulite,garnet\|clinopyroxenite(ecologite) and rare marbles also exist in this unit. Research result indicates that rock of core may have experienced poly\|phase metamorphism and deformation, from early granulite or eclogite facies to late amphibole face.

Evolution-Motion of Crustobodies and Geotectonic Metallogeny

Following the paper entitled A Preliminary Proposal on Crustobody Geotectonics presented by the first author to the 30th IGC in 1996, this paper further extends and elucidates the concept of crustobody in order to make a unifying study of the evolution and motion of crustal structures and to understand the law governing the formation and development of the earth' crust. In this paper the characteristics of crustobody evolution-motion are given. The authors lay emphasis on the relationship between crustobody evolution-motion and tectonic metallogeny. In the end, a multiple dynamic system of the crustobody evolution-motion is discussed from internal and external dynamic forces, and the mantle creep in internal dynamic factors is paid special attention to.

ON INTEGRATIVE GEOTECTONICS

ON INTEGRATIVE GEOTECTONICSChen Guoda(Changsha Institute of Geotectonics, Academia Sinica, 410003,Hunan, China)Xiang Jixi (The Chinese Academy of Geological Sciences, Beijing, China)integrative geotectonics, crustobody geotectonics,multi-origined and polygenetic compound resultantforce system, tectosphere, gradual change, mutation, catastrophismBased on historistic-causationist geotectonics proposed by Chen Guoda in1992, the authors attempt to further extend its contents and ranges, establish integrative geo-tectonics with wide ranges and higher synthesis. Integrative geotectonics is defined as a disci-pline to study very synthetically the whole history and causationistic relations of formation and evolution of the global tectonics (including the crustal and deep teetospheric structures) with the comprehensive analysis method. It is also called as "crustobody geotectonics" for its main geotectonic element is crustobody. Its characteristics are: (1) regarding the internal and exter-nal

PRELIMINARY STUDY ON GEOTECTONIC EVOLUTION AND METALLOGENIC CONDITIONS OF JIAODONG GOLD METALLOGENIC PROVINCE,SHANDONG, CHINA

The results have demonstrated that the studying area underwent four stages of geotectonie evolution,namely, pre-geosyneline, geosyneline, platform and diwa stages. The gold deposits were formed during diwa stage of the iste Yanshanian Age, undergoing multi-tectono-magmatic activities. Jiaodong Group of the Upper Archean Erathem was the source bed of gold deposits. Granitie msamatic aetivities dived the ore-forming elements transporting. Tectonic activities controlled the formation, the distribution of gold deposits and the scale and the shape of ore body, ete.. The gold deposits exhibit the eharacteristics multi-source of ore-forming elemcnts, multi-genesis, multi-ote-conttolling foctors, multi-genstical types and multi-stage mineralization. They belong to mantle-erust deposits.

A PRELIMINARY PROPOSAL ON CRUSTOBODY GEOTECTONICS

Geosyncline-platform geotectonics is aimed at the reconstruction of the Earth’s tectonic evo-lution history, and belongs to the category of historic geotectonics. Plate tectonics exp1ores pri-marily the motion of lithospheric blocks and belongs to the category of dynamic geotectoncis. Eachof them has its own advantages and strong points. However, both are difficult to meet the require-ments for an overall research on all-round tectonic problems- In order to make use of each one’sadvantages more effectively, an integrative, new type geotectonics called crustobody geotectonicsis here proposed. It is a branch of geotectonics which deals integratively with both evolution andmovement of the Earth’s crust by means of the concept of crustobody and the historic-dghamic in-tegrative analysis method.

REPLACEMENT PATTERNS OF GEOTECTONIC UNITS

REPLACEMENT PATTERNS OF GEOTECTONIC UNITSLi Yuping(Dept. of Chemical Science and Engineering, Hunan Univ. , Changsha, China, 410082)replacement pattern, geotectonic unit, Diwa theoryBase upon the Diwa theory and the studies of evolution process of geotectonic units, this paper has advanced that there are many replacement patterns of the geotectonic u-nits in their evolution process. There are three replacement patterns (eg. sudden change (nor-mal) pattern, gradual change and progressive pattern) during the platform region substitutes the geosynclinal region and three replacement patterns (eg. normal pattern, surpassive pattern and progressive pattern) when the Diwa region develops from pre-Diwa regions. The knowl-edge of these regularity is of important significance for us to deeply study the evolution of geo-tectonic unit and the development of the crust.

Crustobody─A New Concept ofIntegrative Geotectonics

The crustobody is a concept of tectonic element established for integrating the research airns, objects and methods of historic and dynamic geotectonics in order to study the tectonics of the earth in an all-round way. It caTries the implications of both evolution and rnovernent, lying equal stress on both development viewpoint and connection viewpoint and giving consideration to both tirne and space. It has the nature, characteristics and functions of the above-mentioned two tectonic elements. On the one hand, though consisting of historic tectonic elernents such as geosynclinal, platform and geodepression (diwa) regions, it puts emphasis on their changing state in spatial rnigration, thus differing from them. On the other hand,though sirnilar in form to plate, a dynamic tectonic element, it places eruphasis on the changing state in its temporal evolution and has other distinguishing characteristics, thus differing from it.

A PRELIMINARY APPROACH TO THE GEOTECTONIC EVOLUTION HISTORY AND MINERLIZATION IN VICTORIA, AUSTRALIA

According to the available data and field research, based on the diwa theory, the authors have studied the geotectonic evolution history and the associated minerlization in the Victoria area. It has been shown that this area is in fact a part of the Lachlan diwa region. The Victoria area can be divided into geodome fault fold zone and subsidence zone. The former can be subdivided into three zones, from west to east, which are western uplift zone, central depression zone and eastern uplift zone. The evolution history of the Victoria area can be divided into four stages——Pregeosyncline, geosyncline, plateform and diwa. Each stage has distinct sedimentary, magmatic and structural features. Of the four stages, diwa stage is the most important for minerlization. Diwa stage started in the Devonian. During the development of diwa, a number of granites, which are characterized by high SiO 2 and Na 2O+K 2O, were formed. The granites were abundance with mineral forming material. On the other hand, diwa geotectonism reformed and enriched the geosynclinal or platform ore deposits. Therefore, most of the ore deposits that occurred in the Victoria area are, more or less, related with diwa tectonism.

MY WORK ON REGIONAL GEOTECTONICS & PLATE TECTONICS

I graduated as a geology major from the former Zhongyang (National) University in 1938 and then worked as a research scholar at Kings College in the University of London from 1949 to 1951.I was one of the pioneers in plate tectonic and terrain tectonic studies in China,devoting myself to the regional geotectonics and plate tectonics of southern China for several decades,making significant achievements in these fields.Throughout the life-long course of my academic career,I have published and coauthored some 120 research papers or monographic books at home or abroad.