Occurrence of Bindheimite in North‐West Queensland

Bindheimite has been identified in specimens from the Lvov Lease, N.W. Queensland. Chemical, microscopic and X‐ray data are given for the mineral which was found to possess a cubic lattice with a unit cell dimension of 10–427 A.     

“Washed away”—assessing community perceptions of flooding and prevention strategies: a North Queensland example

This article explored the perceptions of residents of a regional city in North Queensland of how to remain safe during flood events. It also explored reasons for and how to prevent risk-taking behaviour in floodwater using the protection motivation theory (PMT). PMT is a psychological theory which has recently been applied to assess behaviour during floods and was used as a framework to analyse the themes of responses to the online survey. The online survey was conducted prior to the wet season of 2011/2012 with 130 Townsville residents participating. The results indicate that about half of respondents (55 %) had some experience with floods of which driving through floodwater (38 %) was the most common type of flood experience listed and was more common amongst male respondents. Respondents’ advice to keep friends and family safe during floods was consistent with “coping appraisal”, which would improve their ability to cope with the flood. Prior experiences with floodwater influenced the reasons given for why people drive through floodwater and were taken to be indicative of an actor/observer bias. Respondents who had experience driving through floodwater (the actors) indicate how the context of the situation can influence decision-making, whereas those respondents who had no personal experience of driving through floodwater (the observers) were more likely to cite low perceived vulnerability of harm as a motivator. Prevention strategies focused on structural mechanisms to block access, information provision and punishment of offenders. It is suggested that in communities which regularly experience flooding, timely and context-specific reminders of the dangers inherent in floodwater along with the type, effectiveness and cost of protective action could minimise the public’s contact with floodwater and prove useful regardless of past experiences.     

Facies in a Devonian‐Carboniferous volcanic fore‐arc succession,Campwyn Volcanics,Mackay district,central Queensland∗

The Middle Devonian to Early Carboniferous Campwyn Volcanics of coastal central Queensland form part of the fore‐arc basin and eastern flank of the volcanic arc of the northern New England Fold Belt. They consist of a complex association of pyroclastic, hyaloclastic and resedimented, texturally immature volcaniclastic facies associated with shallow intrusions, lavas and minor limestone, non‐volcanic siliciclastics and ignimbrite. Primary igneous rocks indicate a predominantly mafic‐intermediate parentage. Mafic to intermediate pyroclastic rocks within the unit formed from both subaerial and ?submarine to emergent strombolian and phreatomagmatic eruptions. Quench‐fragmented hyaloclastite breccias are widespread and abundant. Shallow marine conditions for much of the succession are indicated by fossil assemblages and intercalated limestone and epiclastic sandstone and conglomerate facies. Volcanism and associated intrusions were widely dispersed in the Campwyn depositional basin in both space and time. The minor component of silicic volcanic products is thought to have been less proximal and derived from eruptive centres to the west, inboard of the basin.     

Meso—Cenozoic lithospheric thermal structure in the Bohai Bay Basin,eastern North China Craton

The Bohai Bay Basin is a region where part of the North China Craton has been thinned and destroyed. It has experienced two periods of crustal thinning that occurred during the Cretaceous and Paleogene, but investigations of its Mesozoic and Cenozoic lithospheric thermal structure are limited. Therefore, in this study,the distributions of mantle heat flow, crustal heat flow, and Moho temperatures during the Meso-Cenozoic are calculated based on analyses of the thermal history of the Bohai Bay Basin. The results indicate that the ratio of mantle heat flow to surface heat flow peaked during the late stages of the early Cretaceous and during the middle to late Paleogene. The corresponding mantle heat flow was more than 65% of the surface heat flow. Moho temperatures reached three peaks: 900-1100℃ in the late stages of the early Cretaceous;820-900℃ in the middle to late Paleogene; and(in the Linqing Depression, Cangxian Uplift, and Jizhong Depression) 770-810℃ during the early Neogene. These results reveal that the Bohai Bay Basin experienced significant geological change during the Cretaceous, including the transformation of lithospheric thermal structure from "cold mantle and hot crust" before the Cretaceous to "hot mantle and cold crust" after the Cretaceous. The results also indicate that the basin experienced two large-scale rifting events.Therefore, this work may provide the thermal parameters for further investigations of the geodynamic evolution of eastern China.     

A Study on Multi-original Potholes in North China Mountain Regions——A Discussion on “Glacial Potholes” and Other “Glacial Landforms” in North China Mountain Regions

华北山地“距今二、三百万年”的“冰臼”绝大部分位于第四纪河谷内,“距今1～2万年”的“冰川壶穴”位于全新世河谷内,与华北山地地貌演化相矛盾;所谓的“冰川地貌”组合不是真正的地貌组合,而是不同时代、不同成因地貌的混合,因此,华北山地不存在冰臼.所谓的“冰臼”是不同时代、多种成因的壶穴——距今2.50Ma前后的河蚀壶穴,距今10～ 20 ka的雪蚀壶穴,距今10ka以来的溶蚀穴、溶蚀—河蚀壶穴、风化—风蚀壶穴、现代壶穴和水潭.     

The Crustal Structure and Seismic Activity in North China

A layered crustal block model of North China has been constructed based on large amount of data from seismic sounding carried out in recent two decades. Some deep fault zones, such as the Zhangjiakou.Penglai and Tancheng-Lujiang fault zones, divide the upper crust of North China into three upper crustal terranes and nine bolcks. There are distinct differences in velocity and depth distributions, which reflects Cenozoic block faulting in North China in the process of formation of the deep structure. The upper crust shows the features of transition in isostatic adjustment. The existence of a low-velocity layer in the middle crust is characteristic of the crustal structure in North China. There seems to be an increase of rheology of the rocks in the lower crust and a persistence of stable regional stress field. The patterns of the Moho on two sides of the Yanshan-Taihang Mountains are different. The relief of the Moho around Beijing, Shijiazhuang and Guangrao where the deep faults join together shows a quadrantal distribution in some degree. The dynamic sources for seismic activity are the NE-SW horizontal compression and the diapirism of the upper mantle. The middle and upper crust, especially the layered block structure has the most significant effects on seismicity, and the occurrence of earthquakes is more closely related to them than to the Moho.     

Metamorphic and metasomatic convergence of basic igneous rocks and lime‐magnesia sediments of the precambrian of North‐western Queensland∗

With increasing intensity of metamorphism, and particularly metasomatism, it becomes more and more difficult to separate amphibolites in North‐western Queensland into ortho‐ and para‐amphibolites, and a stage is reached at which the two are indistinguishable. Field evidence, carefully sought, has enabled the origin of some apparently identical rocks to be determined, and laboratory methods were applied to these rocks to see if grounds for the separation of amphibolites of unknown origin could be determined. None of the six methods tried — mineralogy (including feldspar twinning), chemical analysis (including TiO2 content), spectrography, rock magnetism — proved to be as successful as the field method in distinguishing the two rock groups; some methods used with apparent success elsewhere, such as feldspar twinning or chemical analyses, are found to be unsuccessful here, which suggests that though the problem is world‐wide, solutions are only of local validity.     

The March–April 2014 sequence of earthquakes in North Chile

During March–April 2014 a series of earthquakes occurred around the Iquique city located in the northern Chile region. The two largest events of this sequence are the Mw8.2, April 1, 2014 and Mw7.7, April 4, 2014 quakes. Here we computed the nodal planes of eight of the large and well teleseismically recorded events of this series based on grid search, teleseismic moment tensors inversion, empirical Green's function deconvolution and its stack to average the deconvolutions for the Mw = 8.2, April 1, 2014, synthetic Green's function deconvolution and its stack to average the deconvolutions for the same event and 3D static deformation analysis of the above mentioned events based on the AK135 model. Grid search nodal planes and moment tensors suggest the dominance of reverse faulting. Almost all of the calculated teleseismic moment tensors represent a considerable amount of DC (usually more than 90%) and lower amount of CLVD for this sequence of events. Empirical and synthetic Green's function deconvolution showing down dip rupture propagation and 3D static deformation representing higher amount of vertical deformation in comparison with horizontal deformation components plus the existence of uplift and subsidence. According to the aftershocks distribution there is a bilateral distribution of the aftershocks around the first large event of this sequence that occurred March 16, 2014 (Mw6.7) so that they are approximately limited between the Mw8.2 (at north) and Mw7.7 (at south) quakes. Moreover there exist two bands of regional seismicity during early-mid 2014: a shallow off-shore band between the trench and coast and a deeper inland band under the active volcanic chain (both nearly parallel to the trench).     

The “coal–bauxite–iron” structure in the ore-bearing rock series as a prospecting indicator for southeastern Guizhou bauxite mines

Bauxite deposits in southeastern Guizhou occur in the lower Permian Liangshan Formation. The rock series bearing the sedimentary bauxite exhibit a typical “coal–bauxite–iron” structure, in which the lower part consists of bauxitic shale intercalated with siderite concretions, the middle part consists of bauxitic rock intercalated with multilayer lenticular or earthy bauxite, and the upper part consists of carbonaceous shales and sandstones intercalated with coal seams. The paralic, coastal and paludal depositional environments at one time had a stable tectonic setting. By studying the elemental geochemistry of the ore-bearing rock series, it can be seen that the common presence of the “coal–bauxite–iron” structure has resulted from (1) the extensive desilication and iron depletion during the formation of the sedimentary bauxite due to the varying physical and chemical environment, and (2) the sufficient supply of organic matter by the external environment. Such geological anomalies that resulted from the physical and chemical changes during the formation of the layered structure in the ore-bearing rock series can serve as a mineralization indicator in prospecting for new deposits.     

Fault zone structure and fluid–rock interaction of a high angle normal fault in Carrara marble (NW Tuscany,Italy)

We studied the geometry, intensity of deformation and fluid–rock interaction of a high angle normal fault within Carrara marble in the Alpi Apuane NW Tuscany, Italy. The fault is comprised of a core bounded by two major, non-parallel slip surfaces. The fault core, marked by crush breccia and cataclasites, asymmetrically grades to the host protolith through a damage zone, which is well developed only in the footwall block. On the contrary, the transition from the fault core to the hangingwall protolith is sharply defined by the upper main slip surface. Faulting was associated with fluid–rock interaction, as evidenced by kinematically related veins observable in the damage zone and fluid channelling within the fault core, where an orange–brownish cataclasite matrix can be observed. A chemical and isotopic study of veins and different structural elements of the fault zone (protolith, damage zone and fault core), including a mathematical model, was performed to document type, role, and activity of fluid–rock interactions during deformation. The results of our studies suggested that deformation pattern was mainly controlled by processes associated with a linking-damage zone at a fault tip, development of a fault core, localization and channelling of fluids within the fault zone. Syn-kinematic microstructural modification of calcite microfabric possibly played a role in confining fluid percolation.     

Deformation band populations in fault damage zone—impact on fluid flow

Fault damage zones in highly porous reservoirs are dominated by deformation bands that generally have permeability-reducing properties. Due to an absence of sufficiently detailed measurements and the irregular distribution of deformation bands, a statistical approach is applied to study their influence on flow. A stochastic model of their distribution is constructed, and band density, distribution, orientation, and flow properties are chosen based on available field observations. The sensitivity of these different parameters on the upscaled flow is analyzed. The influence of a heterogeneous permeability distribution was also studied by assuming the presence of high permeability holes within bands. The fragmentation and position of these holes affect significantly the block-effective permeability. Results of local upscaling with a diagonal and full upscaled permeability tensor are compared, and qualitatively similar results for the flow characteristics are obtained. Further, the procedure of iterative local–global upscaling is applied to the problem.     

Species composition and forest structure in tropical moist deciduous forest of Bangladesh—a case study in Thakurgaon

This study was conducted in the tropical moist deciduous forest in Bangladesh to describe the species composition, diversity, and the forest structure. There were three plots established in Ranishonkoil, Ruhia, and Baliadangi forest beat in Thakurgaon. A total of 126 tree species, 1,991 stems (663 ha^?1) of ≥10-cm girth were listed. Tree communities in these forest region differed in dominance, composition, diversity, and structure; and tree stand density varied from 651 to 685 ha^?1. Species diversity (H¹) ranges from 3.11 to 3.48. Meliaceae, Myrtaceae, and Rubiaceae were the most abundant families within the three plot area. Study site 2 is more diverse at spatial scale and taxonomic levels due to high rainfall and favorable edaphic condition. This study will help the foresters as baseline information for monitoring and sustaining diversity of tropical moist deciduous forests in Bangladesh.     

Thinking like a geologist: The culture of geology Mawson lecture 1996∗

Geology plays a crucial role in both the scientific and the popular culture; it has transformed the way ordinary people look at the world over the last two centuries. Much of this transformation is understood in terms of information about the age of the earth, the disposition of the continents, and the evolution of living things. The two main concerns of this paper are with geology as education, and geology as a system of thought, a way of thinking about the world. My central question is how does a grounding in geology affect the cast of mind, the way one thinks, perceives and behaves? What is the culture of geology? Conclusions are of two kinds. Some of the propositions advanced about the nature of geology in relation to the other sciences and our general culture are: (i) there is no hierarchy of the sciences; (ii) geology is a Romantic science rather than a Classical one; (iii) there is no such thing as the scientific method; (iv) geologists often attempt to reconcile competing hypotheses; (v) geological phenomena are often of an almost irreducible complexity and their investigation is beset by problems of scale, both spatial and temporal; and (vi) the concept of ‘universality’ has a distinctive application in geology. Among the non‐professional uses of geology are: (i) human history is incomplete without environmental history; (ii) geology has application in environmental planning and management, but this requires judgement and experience as knowledge of the geology is not enough, it is equally important to know when it can safely be overridden, when it is useful background, and when it is critically important to decision‐making; and (iii) an awareness of the geology of a region enhances the sense of place—our sense of our individual and communal identities owes much to an awareness of place.     

Geochemistry and origin of hornblende‐bearing xenoliths in the I‐type Petford Granite,North‐East Queensland

Hornblende‐bearing xenoliths in the I‐type Petford Granite, north‐east Queensland, show an abundance pattern suggesting redistribution in a convecting magma system and were probably carried up with the host magma. The Petford Granite and xenoliths are chemically cognate, but quartz monzodiorite‐granodiorite bodies (a potential source for the xenoliths) in the adjacent country rocks belong to an independent magma suite. The xenoliths are chemically similar to andesite lavas and dykes 90 km to the NW. They represent fragments of the parental andesite (diorite) of a calcalkaline suite, which fractionated to yield the Petford Granite. They are not source rocks for the granite melt, melt residua, or early cumulates. The fractionated granite melt broke through the earlier envelope of diorite and rose into the upper crust, carrying dioritic fragments with it. Interaction between magma and xenoliths was generally minimal.     

The Basic Conceptions in Geomorphology—Geomorphology as the Study of a Function

正 We owe to Davis the conception that a landform is the function of processes, structure and time. Among these three independent variables, process is a dynamic variable, structure a spatial variable and time a time variable.     

Numerical modelling of fault reactivation in carbonate rocks under fluid depletion conditions – 2D generic models with a small isolated fault

This generic 2D elastic-plastic modelling investigated the reactivation of a small isolated and critically-stressed fault in carbonate rocks at a reservoir depth level for fluid depletion and normal-faulting stress conditions. The model properties and boundary conditions are based on field and laboratory experimental data from a carbonate reservoir. The results show that a pore pressure perturbation of −25 MPa by depletion can lead to the reactivation of the fault and parts of the surrounding damage zones, producing normal-faulting downthrows and strain localization. The mechanism triggering fault reactivation in a carbonate field is the increase of shear stresses with pore-pressure reduction, due to the decrease of the absolute horizontal stress, which leads to an expanded Mohr's circle and mechanical failure, consistent with the predictions of previous poroelastic models. Two scenarios for fault and damage-zone permeability development are explored: (1) large permeability enhancement of a sealing fault upon reactivation, and (2) fault and damage zone permeability development governed by effective mean stress. In the first scenario, the fault becomes highly permeable to across- and along-fault fluid transport, removing local pore pressure highs/lows arising from the presence of the initially sealing fault. In the second scenario, reactivation induces small permeability enhancement in the fault and parts of damage zones, followed by small post-reactivation permeability reduction. Such permeability changes do not appear to change the original flow capacity of the fault or modify the fluid flow velocity fields dramatically.     

Modal analysis by point‐counter — The choice of sample area∗

Point‐counter analyses include two errors, determined separately by count length and by sample area. The counting error has been studied by Chayes, and his latest results admit an estimate also of the sampling error. It is postulated that the sample size and the rock coarseness do not affect this error independently; instead, they combine to determine the effective number of grainsections sampled, and this in turn controls the sampling error. The estimate of the sampling error is compared with that for the counting error in selecting the best sample sizes and count lengths for projected work.