Regional Intrusive Signature from the Cameroon Coastal Basins to Bioko Island in Equatorial Guinea (Gulf of Guinea) Using Gravity Studies

The Gulf of Guinea constitutes an area of great petroleum potential yet with very limited geophysical research information. Consequently in this study, a Bouguer anomaly map has been computed from gravity data covering regions stretching from the Cameroon coastal basins to Bioko island (formerly Fernando Po) which is part of Equatorial Guinea. The data were further processed for Source Edge Detection (SED), Euler 3D deconvolution, 3D surface oriented models and 3D voxel solutions. The results confirmed the presence of previously identified intrusive bodies around the Douala and Kribi/Campo sedimentary sub-basins and went ahead to suggest a probable continuity between these two. A possible extension of this body offshore the Gulf of Guinea right up to Bioko island with very striking similarities was also highlighted and it shows characteristic variations in the depth to the surface of the body at different locations.

Pre-collision Granites and Post-collision Intrusive Assemblage of the Kelameili-Harlik Orogenic Belt

The main types of intrusive rocks in the Kelameili-Harlik Hercynian erogenic belt include calc-alkaline granites, diabase dykes, kaligranites and alkaline granites. Investigation in field geology, petrology, mineralogy and geochemistry shows that the calc-alkaline granites belong to the syntexis-type (or I-type) and were formed in a pre-collisional magmatic arc environment. In consideration of the fact that kaligranites have many features of alkaline granites with higher consolidation temperatures than the calc-alkaline granites and show a discontinuity of minor element and REE evolution in respect to the calc-alkaline granites, they could not have been derived by differentiation of magmas for the calc-alkaline granites, but are likely to have been generated in an environment analogous to that for alkaline granites. The triplet of basic dyke swarms, kaligranites and alkaline granites could be regarded as a prominent indication of the initial stage of post-collisional delamination and extension. These

Alkaline Intrusives at the East Foot of the Taihang-Da Hinggan Mountains:Chronology,Sr,Nd and Pb Isotopic Characteristics and Their Implications

Based on the Rb-Sr isochron dating results, this paper suggests that the alkaline intrusive belt at the east foot of the Taihang-Da Hinggan Mountains were formed between 135 and 122 Ma. And the alkaline intrusives in the north and south sections of this belt have entirely different Sr, Nd and Pb isotopic characteristics, i.e., all the rocks in the south section have positive εSr(t) and negative εNd(t) values and all those in the north have the opposite values. On the εSr(t) versus εNd(t) correlation diagram, the samples from the south are concentrated along the enriched mantle evolution trend lines and nearby, while those from the north fall along the depleted mantle trend lines and nearby. On the Pb isotope composition diagram, most of the samples from the south section fall on the mantle Pb evolution line and nearby, while those from the north lie between the Pb evolution lines of the mantle and the erogenic belt. The above-stated isotopic characteristics not only indicate that the source rocks

Huanggang Intrusive Complexin Northern Tongbai Area:Island-Arc Tectonic Environment and Its Geological Significance

ＩＮＴＲＯＤＵＣＴＩＯＮＲｅｃｅｎｔｇｅｏｌｏｇｉｃａｌｓｔｕｄｉｅｓｓｈｏｗｔｈａｔｔｈｅＥｒｌａｎｇｐｉｎｇｏｐｈｉ－ｏｌｉｔｅｆｒａｇｍｅｎｔｗａｓｆｏｒｍｅｄｉｎｂａｃｋ－ａｒｃｂａｓｉｎ（Ｓｕｎｅｔａｌ．，１９９６；Ｗａｎｇｅｔａｌ．，１９...

Spatial Distribution and Ages of Alkaline Intrusive Rocks in China and Related Tectonics

On the basis of the geological data from 220 intrusions and isotope ages of 115 rock bodies, the paper discusses the distribution of 18 alkaline intrusive rock belts along deep faults and their relations to the plate tectonic activity. In view of the presence of a large amount of Variscan alkaline rocks of deep-source character, it is inferred that mantle diapirism was very strong in China during the Variscan. Besides anorogenic and postorogenic alkaline granites, there also occur alkaline granites formed in the terminal orogenic stage when the regional tectonic activity was of compressional nature. Finally, the paper discusses the tectonic environment of the Maoniuping nordmarkite in Mianning county, Sichuan province, and the authors consider it to be a compressional environment originating after rift closing.

The State-of-the-Art Review on Applications of Intrusive Sensing,Image Processing Techniques,and Machine Learning Methods in Pavement Monitoring and Analysis

In modern transportation,pavement is one of the most important civil infrastructures for the movement of vehicles and pedestrians.Pavement service quality and service life are of great importance for civil engineers as they directly affect the regular service for the users.Therefore,monitoring the health status of pavement before irreversible damage occurs is essential for timely maintenance,which in turn ensures public transportation safety.Many pavement damages can be detected and analyzed by monitoring the structure dynamic responses and evaluating road surface conditions.Advanced technologies can be employed for the collection and analysis of such data,including various intrusive sensing techniques,image processing techniques,and machine learning methods.This review summarizes the state-ofthe-art of these three technologies in pavement engineering in recent years and suggests possible developments for future pavement monitoring and analysis based on these approaches.

Mesozoic Volcanic-Intrusive Complexes in the Coastal Area of Southeastern Zhejiang Province: Their Features, Petrogenesis and Distribution Pattern

On the basis of previous studies and by means of field geological, remote sensing, petrographical,mineralogical, petrochemical and geochemical investigations, the authors studied the temporal-spatial distribu-tion of the regional structures, volcanic structures and products of volcanic activity in the coastal area ofsoutheastern Zhejiang. On the basis and through a systematic comparison of the products of magmatism in thearea, it is considered that there exists a compsite volcanic structural belt composed of linear and circular struc-tures and it has been demonstrated that there exist volcanic intrusive complexes--"trinity" composed of vol-canic, subvolcanic and plutonic rocks. It is suggested that the volcanic intrusive complexes in the area belong tothe typical syntexis series and that its materials were derived from a mixed source of crust and mantle.

Geological characters and petrological characters of metamorphosed medium-acidic intrusive complexes in Ludong Orogenic Belt,China

Ludong orogenic belt in China is an importantal continent collision orogenic belt in eastern Asia, between Sino Korean landmass and Yangtze landmass. The host rock of the orogenic belt is metamorphosed medium acidic intrusive complexes, which can be divided into four types, that’s, quartz dioritz, granite dioritz, monzonitic granite and undertint monzonitic granite, principal minerals are plagioclases, potassium feldspars and quartzs, minor minerals are hornblendes, biotites, clinopyxenes and garnets, accessory mineral types and assemblages are very similar, specially, various rocks are mainly fine grained textures. They have the history of regional amphibolite facies metamorphism and deep middle shallow structural layer deformation, and are changed into various gneiss and tectonic system. There are many xenolithes of middle Proterozoic eclogite host rock extrahigh high pressure metamorphic complexes, a small xenolithes of early Proterozoic layered metamorphite system and granulites, and ultrabasic basic rocks of various epoches in the metamorphosed medium acidic intrusive complexes.

Isla San Pedro Nolasco as a Late Miocene intrusive record at the eastern margin of the Gulf of California:Insights from geological,geochemical and geochronological studies

Isla San Pedro Nolasco(ISPN)is a structural high bounded by inactive dextral oblique-slip faults in the east-central part of the Gulf of California rift zone and is composed of intrusive rocks not exposed on other Gulf of California islands.Here we present the reconnaissance results from geological mapping,as well as first geochemical and geochronological data for the ISPN intrusive complex.The intrusive rocks compose a sheet-like body of intermediate and felsic composition intruded by an intermediate and acidic dike swarm.All intrusive rocks(host and dikes)range in age from ca.9 Ma to 10 Ma(^(40)Ar/^(39)Ar)and show a hydrous ferromagnesian mineral association(amphibole and biotite)with a calc-alkalic and transitional affinity.This hydrated mineralogical association has not been recognized in the coeval rocks along the onshore western margin of the North American plate(coastal Sonora).However,such hydrous mineralogical association is found in the coeval rift transitional volcanic rocks from the Baja California Microplate at Santa Rosalía and Bahía de LosÁngeles–Bahía de LasÁnimas.The ISPN continental block,at least 40 km long,has been pulled apart by transtensional faulting of the late Miocene Gulf of California shear zone before the westward migration of the North America-Pacific plate boundary at ca.3–2 Ma.Eventually,ISPN became isolated as an island during the late Miocene flooding of the Gulf of California seaway.

Petrography and Tectonic Setting of Dykes in the Granitoid Intrusive, South to East-Qorveh(Kurdistan Province), Iran

The studied area is located in the south to east of the Qorveh city(Kurdistan Province)in the Sanandaj-Sirjan zone.Based on field observations,the dykes are mafic to dioritic in composition,and followed by granitic

Intrusive Thoughts and Executive Functions in Obsessive Compulsive Disorder

Objectives: Our aim was to compare the effects of an unwanted intrusive thought on executive function in a group of people with Obsessive Compulsive Disorder (OCD) and in a healthy group. Method: The Behavior Rating Inventory of Executive Function Adult (BRIEF-A) was used to measure executive dysfunction in everyday life in people with OCD. The study participants underwent either an intrusive thought induction or neutral thought induction prior to the administration of three computer-based tests of executive function. Results: The BRIEF-A results confirmed the impairment of executive function in everyday life for patients with OCD. In the number-letter task, patients with OCD displayed a longer reaction time (relative to the controls). There were no intergroup differences in the local-global task. In the go/no-go task, there was a significant impairment (p = 0.03) in the OCD group (with more commission errors than controls). There was a non-significant trend towards an effect of thought induction in both groups in the number-letter task. However, intrusive thought induction did not have a greater effect than neutral thought induction on the OCD group in any of the tasks. Conclusions: Intrusive thought induction has no effect on executive function in the two groups. The two groups differed with regard to two executive tasks.

Geochronology and geochemistry of early Paleozoic intrusive rocks from the Khanka Massif of the Russian Far East

The Russian Far East and Northeast(NE)China are located in the eastern part of the Central Asian Orogenic Belt(CAOB),which consists of a series of micro-continental massifs including the Erguna,Xing’an,Songnen–Zhangguangcai Range,Bureya,Jiamusi,and Khanka massifs.The Khanka Massif is located in the easternmost part of the CAOB,mainly cropping out in the territory of Russia,with a small segment in NE China.To the north and west of the Khanka Massif are the Jiamusi and Songnen–Zhangguangcai Range massifs,respectively.The boundary between these massifs is marked by the Dunhua–Mishan Fault.To the south lies the North China Craton,and to the east is the Sikhote–Alin Orogenic Belt separated by the Arsenyev Fault.However,the early Paleozoic evolution and tectonic attributes of the Khanka Massif are debated.These conflicting ideas result from the lack of systematic research on early Paleozoic igneous rocks from the Russian part of the Khanka Massif.It is generally accepted that the CAOB represents the largest known Phanerozoic accretionary orogenic belt.However,questions remain concerning the nature of the deep crust beneath the Khanka Massif,and whether Precambrian crust exists within the massif itself. In this paper,we report new zircon U–Pb ages,Hf isotopic data,and major-and trace-element compositions of the early Paleozoic intrusive rocks from the Khanka Massif of the Russian Far East,with the aim of elucidating the early Paleozoic evolution and the tectonic attributes of the Khanka Massif,as well as the nature of the underlying deep crust. New U–Pb zircon data indicate that early Paleozoic magmatism within the Khanka Massif can be subdivided into at least four stages:~502 Ma,~492 Ma,462–445 Ma,and^430 Ma. The^502 Ma pyroxene diorites show negative Eu anomalies,and the^492 Ma syenogranites,intruding the^502 Ma diorites,show positive Eu anomalies.These observations indicate that the primary parental magmas of these rocks were derived from different origins. The 462–445 Ma magmatism is made up of syenogranites and tonalites.The^445 Ma Na-rich tonalites contain low REE concentrations,and are enriched in Eu and Sr.These observations,together with the positiveεHf(t)values,indicate that they were derived from magmas generated by partial melting of cumulate gabbros. The^430 Ma I-type granodiorites and monzogranites from the northern Khanka Massif,and the A-type monzogranites from the central Khanka Massif display zirconεHf(t)values ranging from–5.4 to+5.8.This suggests that they formed from magmas generated by partial melting of heterogeneous lower crustal material. Zircon Hf isotopic data reveal the existence of Precambrian crustal material within the Khanka Massif.The geochemistry of the Middle Cambrian intrusive rocks is indicative of formation in an extensional setting,while Late Cambrian–middle Silurian magmatism was generated in an active continental margin setting associated with the subduction of a paleo-oceanic plate beneath the Khanka Massif.Regional comparisons of the magmatic events indicate that the Khanka Massif has a tectonic affinity to the Songnen–Zhangguangcai Range Massif rather than the Jiamusi Massif.

MODELLING OF COMPOSITION OF MANTLE SOURCE FOR THE JIJIE ALKALINE-ULTRABASIC INTRUSIVE COMPLEX, LUFENG, YUNNAN

Based on the data on petrology and geochemisty for the Jijie alkaline-ultrabasic intrusive rock complex, this paper, by means of correlation, suggested that the average composition of melteigites with 10% olivine added (Fo=86) can be considered as the composition of the primary magma of the Jijie complex. This magma, whose composition is estimated from the incompatible element P2O5, was produced by 3%±partial melting of pyrolites. The results of Petrological Mixing Calculating showed that the mantle-source rocks of the Jijie complex are obviously depleted in incompatible elements.

Petrogenesis of Adakitic Intrusive Rocksin Xu-Huai Area, Eastern China

The research of the petrology and the geochemistry of the Mosozoic intrusive rocks in Xu-Huai area indicated that they are mainly composition of dioritic porphyry and monzodioritic porphyry, and the features of the petrology and geochemistry of the Mosozoic intrusive rocks are extremely similar to those with the typical adakites. Combined with the petrography and the testimated results of the deep-seated xenoliths in the intrusive rocks, it indicates that the petrogenesis of the Mosozoic intrusive rocks could be resulted from the partial melting of amphibole-bearing garnet pyroxenite and garnet amphibolite in lower continental crust in this area.

HYDROCHEMICAL INDEXES OF SEAWATER INTRUSION AND COMPREHENSIVE JUDGEMENT ON INTRUSIVE DEGREE

１ＴＨＥＨＹＤＲＯＣＨＥＭＩＣＡＬＩＮＤＥＸＥＳＦＯＲＴＨＥＪＵＤＧＥＭＥＮＴＯＮＳＥＡＷＡＴＥＲＩＮＴＲＵＳＩＯＮＴｈｅｈｙｄｒｏｃｈｅｍｉｃａｌｃｈａｒａｃｔｅｒｉｓｔｉｃｉｓｔｈｅｄｉｒｅｃｔｂａｓｉｓｆｏｒｔｈｅｊｕｄｇｅｍｅｎｔｏｎｓｅａ...

Chronology, Geochemistry and Geological Significance of Haizi Bimodal Intrusive Bodies in Wuding District, Central Yunnan

The Haizi diabase-granite porphyry composite rock mass is located in the Wuding-Yanjing taphrogenic trough within the Paleoproterozoic Kangdian fault-uplift zone. According to field observations, the diabase is divided into two types: central facies and marginal facies;the granite porphyry directly contacts the central facies of diabase without transitional intermediate rock. In order to disclose its geological and petrological significances, this paper carried out the LA-ICP-MS zircon U-Pb dating and geochemical investigation on both masses of Haizi diabase and granite porphyry. The results showed that the207Pb/206Pb weighted average age of granite porphyry is 1764 ± 18 Ma and diabase 1765 ± 5.4 Ma. The geochemical investigations revealed that the Haizi diabase is a kind of high-potassium alkaline basalt and the granite porphyry a kind of low-potassium rhyolite, both enriched with high field intensity elements and depleted in large-ion lithophile elements;there is obvious component intermittence between the diabase and the granite porphyry, both being bimodal and showing characteristics of continental rift valley magmatite. The?in situ?Hf isotope of dating zircon showed that mantle materials participated in the formation and emplacement of Haizi granite porphyry and crust materials participated in the formation of diabase. This meant that crustal remelting and accretion of new crust occurred in this region in the 1.7 Ga period. It can be therefore inferred that the Haizi bimodal intrusive rock came into being due to the breakup of Kunyang rift valley and rapid ascent of mantle materials in the 1.7 Ga period, which echoed the global Columbia supercontinent breakup and was the first petrological record of that breakup found at the southwest margin of Yangtze platform.

Fluid Mechanics of Intrusives

The fluid mechanics of dike emplacement are analyzed using the translatory wave theory. The stress strain relations in the host rock are assumed linear and the fracture resistance of the host rock is assumed small. The resulting model is a flowing dyke progressing upwards to the surface with constant speed and a very small side slope. Apart from the topmost section, the form of the dyke is very close to the static form corresponding to the magma pressure in a no-flow situation. Two scales are found that control the flow, a width scale and a composite stiffness parameter for the host rock, representing the properties of the rock and the magma such as elasticity and viscosity. The theory explains a number of special features for dykes that are already known by researchers. It also adds two new points, the most interesting being that the composite stiffness of the rock can be estimated from field observations of the downwards widening angle of the dyke.

Geochemical Study of Almoqlaq Intrusive Body in North of Asadabad in Hamedan Province, Iran

The study area is located in the west of Iran and in the north of Asadabad. This is the range between Eastern lengths of 00', 48° to 15', 48°, and northern latitudes of 45', 34° to 00', 35°. This range is limited from north to the asphalt road of Hamadan Qorveh, Sanandaj, and from the East and Southeast, to Asadabad of Kermanshah-Hamedan road, and from the West to Chahardoli plain and from the south to the plains and the town of Asadabad. According to the geological map of the study area, intrusive outcropping of diorite-gabbro of Almoqlaq, and quartz syenite is at Almoqlaq mountains. Intrusive rocks of the region, based on the total Alkali oxide, against silica rocks of study area fall within the quartz monzonite, gabbro, granodiorite, granite, and syenite between quartz and alkali granite. And granite in the study area (due to aluminum saturation index), is in the range of metaluminous, and metaluminous to peraluminous. Based on normalized spider diagram with the upper crust, the typical study area belongs to this model, and most of the elements are placed near or on standard line of 1.

Permian tectonic evolution and continental accretion in the eastern Central Asian Orogenic Belt:A perspective from the intrusive rocks

The tectonic evolution and history of continental accretion of the eastern Central Asian Orogenic Belt(CAOB)are not yet fully understood.In this study,we investigate Permian intrusive rocks from the Jiamusi Block of the eastern CAOB to constrain the tectonic evolution and continental accretion of this region during the late-stage evolution of the Paleo-Asian Ocean.Our new data show that Early Permian gabbro-diorites were derived from the partial melting of depleted mantle metasomatized by oceanic-slab-released fluids.Middle Permian adakitic granites have low Na2O and MgO and high K2O contents,indicating a thickened-lower-crust source.Late Permian S-type granites were derived from the partial melting of continental crust.A compilation of the available geochronological data for Permian intrusive rocks(including adakitic and A-,S-,and I-type granites and mafic rocks)from the eastern CAOB reveals that the A-type granites formed mainly during the Early–Middle Permian,S-type and adakitic granites mostly during the Middle–Late Permian,and I-type granites and mantle-derived mafic rocks throughout the Permian.The A-type granites,which are proposed to have been sourced from thinned continental crust,indicate an extensional setting in the eastern CAOB during the Early Permian.The Middle–Late Permian adakitic granites imply a thickened continental crust,which indicates a compressional setting.Therefore,the eastern CAOB underwent a transition from extension to compression during the Middle Permian,which was probably triggered by the late-stage subduction of Paleo-Asian oceanic crust.Considering the petrogenesis of the intrusive rocks and inferred regional tectonic evolution of the eastern CAOB,we propose that vertical underplating of mantle-and oceanic-slabderived magmas contributed the materials for continental crust accretion.

Petrogenesis and Tectonic Implications of the Late Silurian–Early Devonian Bimodal Intrusive Rocks in the Central Beishan Orogenic Belt,NW China:Constraints by Petrology,Geochemistry and Hf Isotope

A large number of Late Silurian–Early Devonian intrusive rocks are distributed in the central Beishan orogenic belt(BOB).Tectonic setting of these intrusive rocks is of great significance to the study of the subduction and accretion of the Paleo-Asian Ocean.Previous studies show that most of the intrusive rocks in this region are S-type or A-type granitoids.In this study,we firstly reported the Late Silurian–Early Devoniandia bases,granodiorites on the southside of the Baiyunshan ophiolitic mélanges belt,as a part of Hongliuhe-Xichangjing ophiolitic mélanges belt(HXOMB).Zircon LA-ICP-MS U-Pb dating yields emplacement ages between 418 and 397 Ma,REE distribution patterns exhibit enriched LREE and flat HREE in the diabases,the discriminant diagrams show that the diabases have geochemical characteristics of intraplate basalt.The granodiorites in this paper present more like S-and A-type granitoids reported,showing the geochemical characteristics of syn/post-collision granites.Actually,the bimodal magmatic rocks are developed during Late Silurian–Early Devonian on both sides of the HXOMB,which are related to the tectonic background of the post orogeny extension.The diabases are tholeiitic with relative strong depletedεHf(t)(+8.1 to+13.0),which are mainly from relative depleted mantle.The granodiorites are calc-alkaline with relative slightly depletedεHf(t)(+0.7 to+5.6)and the lower Mg#and MgO contents(34.6–36.9,0.50 wt.%–1.19 wt.%respectively),reflecting the source characteristics of meta-basalt.Therefore,the remelting of juvenile crust may be the main way of continental crust accretion during Late Silurian–Early Devonian in the central BOB.