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The article by Davies et al. discusses scientific studies on microbially induced sedimentary structures (MISS). The sedimentary structures are caused by benthic microbes in clastic deposits and have the potential to fossilize. In the opinion of Davies et al., it may be problematic to distinguish MISS-like structures (e.g., ‘wrinkle structures’) from similar, but abiotic structures. Therefore, their article argues, there exists a need for an umbrella classification summarizing both biological and abiotic sedimentary structures. However, Davies et al.'s paper does not reflect a thorough understanding of the formation and preservation of MISS. More so, while the authors appreciate the benefit of geological field work, and petrological as well as geochemical laboratory sample analyses, their article appears to widely disregard that this scientific rigor is presented in studies on MISS. The lack of data make the classification by Davies et al. unsupported and difficult to use. It potentially confuses by producing multiple classification possibilities rather than a pragmatic organization, and it contributes an unnecessary terminological ballast to a research area that has progressed far beyond to the concepts that the paper by Davies et al. presents.

In their discussion paper, Sumegi & Gulyas (2021) expressed their concerns about our remarks regarding the reliability of malacothermometer-based July paleotemperature reconstructions for the Carpathian Basin as published in Obreht et al. (2019). We are content to see that our paper inspired the continuation of the discussion, however, we have some concerns about the criticism expressed by Sumegi and Gulyas (2021), which we in this reply address.

We discuss the new causative source model for the 1908 Messina Straits earthquake recently proposed by Barreca et al. (2021), where an aseismic slip of 1.13 m along a low-angle discontinuity, preceding the 1908 earthquake, have mechanically destabilized a set of overlying faults, therefore leading them to the rupture. The lack of significant variations of the relative sea level in the Messina harbor area, in the time period relevant for the levelling data (1907–1908) analyzed by Barreca et al., and at least for the decade preceding the event proves the inconsistency of the assumed pre-earthquake aseismic slip. A careful interpretation of crustal earthquake distribution in the Strait does not support the presence of the low-angle discontinuity. The modelled horizontal coseismic pattern reveals a scenario that is not supported by any other independent geological and geophysical observation. We conclude that the source model proposed by Barreca et al. for the 1908 Messina Straits earthquake can not be considered as a viable hypothesis for the causative fault.

The article published by Obu et al. (2019) estimating the occurrence of permafrost over a Northern Hemisphere. The results published differ from those presented in previous works. This comment highlights the errors introduced in that study, and in a positive note, its cause and proposed solution. The problem remains beyond capabilities of computed models or empirical research. Its solution lies in using the correct categories and land classifications, and clearly defining the medium subjected to freezing. In particular, the correct classification of ice plays a decisive role here. To provide a full picture of the occurrence of permafrost on the Earth surface, three different media must be considered: 1) exposed land, traditionally understood as “dry land”, 2) glaciers and ice sheets together with its bed and 3) the sea floor (continental shelves). The biggest weakness of the published study is not including glaciated areas in their estimations. The authors do not take either a clear position in this crucial matter, despite a radical divergence of opinions has emerged in recent years. Whether and in what way Greenland or other glaciated areas are covered by permafrost remains a pressing issue, as the final determination of the range of the permafrost worldwide depends on it. Until then, any criteria or benchmark used will continue to be ambiguous and open to discussion, maintaining the discrepancy at millions of square kilometers.

Gierlowski-Kordesch and Cassle (2015, Earth-Science Reviews 148, 209–227) interpreted microconchids (extinct tentaculitoid encrusters) as strictly marine, rejecting the previous conclusions that these organisms occupied a variety of habitats ranging from marine to non-marine. We argue that due to misunderstanding of previous statements concerning the affinity of microconchids, the authors used an actualistic approach and incorrectly compared microconchids with modern phoronids, which led to oversimplifications and misinterpretations. Also their idea that microconchids, as supposedly strictly marine organisms, were preserved in non-marine settings only because of transport by storm surges and tsunamis is unsupported on paleontological grounds. These errors led to mistaken conclusions about microconchid paleoecology that must be discussed in order to avoid an erroneous interpretation of microconchid paleoenvironments.

Globally, fly ash (FA), generated in huge quantities from coal fired power plants is a problematic solid waste. Utilization of FA as an ameliorant for improving soil quality has received a great deal of attention over the past four decades, and many studies have been carried out worldwide. The silt-sized particles, low bulk density (BD), higher water holding capacity (WHC), favorable pH, and significant presence of plant nutrients in FA, make it a potential amendment for soils. The studies suggest enormous potential for the use of FA to improve cultivable, degraded/waste land, mine soil, landfills, and also to reclaim abandoned ash ponds, for agriculture and forestry. FA application improves the physical, chemical and biological qualities of soils to which it is applied. However, in some cases, depending on the characteristics of FA, the release of trace elements and soluble salts from FA to a soil–plant–human system could be a constraint. The effect is minimal in the case of weathered FA. The findings reflected the heterogeneity of ash characteristics, soil types, and agro-climatic conditions, thus a generalized conclusion on the impact of FA on plant species and soil quality is difficult. It is very important that the application of FA to soil must be very specific depending on the properties of the FA and soil. A considerable amount of research has been carried out to blend FA with varieties of organic and inorganic materials, like lime, gypsum, red mud, animal manure, poultry manure, sewage sludge, composts, press mud, vermicompost, biochar, bioinoculants, etc. Co-application of FA with these materials has much advantage: enhanced nutrient availability, decreased bioavailability of toxic metals, pH buffering, organic matter addition, microbial stimulation, overall improvement in the general health of the soil, etc. The performance of FA blending with organic and inorganic materials is better than FA alone treatments. Farm manure was found to be the most promising amendment used along with FA. While using FA in agriculture as a soil ameliorant, it is better to seek the locally available fitting blend materials for exploiting the benefits from their synergistic interaction. However, continuous research in parallel for long durations to dispel apprehension, if any, is desirable under well defined regulatory measures.

The Korean Peninsula (KP) occupies a junction area of three big tectonic domains that are the Paleo-Central Asian Orogenic Belt, Paleo-Tethyan Orogenic Belt and the Western Pacific Orogenic Belt. Therefore the KP is a key area to understand the Northeast Asian and even global geotectonic evolution. In terms of geological unit division, the KP has long been thought to be closely tied with the mainland of China, with using collective term the Sino-Korea Craton for the North China Craton (NCC). However, such correlation suffered from the absence of relevant geological information in North Korea (NK). To bridge this knowledge gap, our group carries out a long-term collaborative study between the two-sides of the KP and China，and organized united field investigation in the North Korea, South Korea (SK) and China as possible. This paper introduces general geology in the North Korea，and simply make comparison with the NCC and South Korea. These pioneering works culminated in the following summaries. (1) The KP comprises three major Precambrian massifs, i.e., Rangnim, Gyeonggi and Yeongnam massifs. The Rangnim and Gyeonggi massifs are separated by the Imjingang Structural Belt, while the Gyeonggi and Yeongnam massifs are separated by the Ogcheon Structural Belt. (2) The basement of the Rangnim massif is correlated with that of the NCC. The characteristic metamorphic rocks of high- temperature/high-pressure granulite facies including meta- sedimentary rocks (kondalites and meta-sandstones and marbles) with ~1.9–1.8 Ga metamorphic ages occur in the three massifs, similar to the NCC. (3) The Proterozoic rift sedimentary sequences are developed in the NCC and North Korea, but Lower Paleoproterozoic strata are rare, and Neoproterozoic strata are more developed in North Korea relative to the NCC. (4) Two main Paleozoic basins within the Rangnim massif and within the Gyeonggi and Yeongnam massifs are the Phyongnam basin and Taebaeksan Basin. Both of them have a similar Paleozoic tectono-stratigraphy to the NCC. (5) Although the nature and tectonic significance of the Imjingang belt remains controversial, it doesn't show characteristics and natures of collisional orogenic belt. (6) The eclogite-bearing Hongseong Complex (HSC) is located in the southwestern part of the Gyeonggi Massif in South Korea, but no similar rock unit has been found in North Korea. (7) Mesozoic igneous rocks are widespread throughout the northern and southern parts of the KP. Triassic magmatism is related to Indosinian orogeny. Jurassic and Cretaceous igneous rocks are different and irregular from those in the NCC on age and spatial-temporal distribution. This paper also suggests several key and controversial academic issues that are worthwhile to study in the future.

Since Australia is the driest inhabited continent, it is a natural laboratory to study on a large scale dust, its composition, its sources, transport and geochemical composition. This is necessary as there has been a lack of appreciation of the diversity of the Australian regolith characterized by a great array of ages and compositions. This is particularly true of studies that examined the geochemistry of Australian dusts and links with potential deposition sites such as in Antarctica and comparison with South America. Hence, the first part of this paper provides an overview of the surficial geology of Australia with emphasis on regions from where dust can become deflated. A review follows on the investigations of significant dust transport and events in Australia. The second part of the paper provides a review of the sites of potential deflation of dust. It includes the study of different geomorphological sites of dust deflation, with a discussion on how dust particles can accumulate in regions linked to large playa lakes that are under the influence of groundwater below them. This is an important mode of dust deflation, a process of which had insufficiently been detailed before. The processes involving evaporative pumping are explained and several illustrations are provided to document those processes and location of dust deposits. Another region of importance to dust deflation consists of extensive alluvial plains and these are also documented, with an area in the upper reaches of the Darling River being now documented more fully. Finally, the inter-dunal corridors in large dune fields are also mentioned as a source of dust as previous studies already show. This second part ends with the description of the two main Potential Source Areas (PSA) of dust in Australia and these are the Kati Thanda-Lake Eyre region of central Australia, and the Darling Riverine Plain in the upper reaches of the Darling River. These two regions are important for their geochemical fingerprints for transcontinental studies, and supported by satellite imagery that identify dust plumes originating from these regions. The third part of the paper examines the geochemical composition of Australian PSAs by paying particular attention to Neodymium, Strontium and Lead isotopic ratios from both continents. We also suggest the possibility of combining Nd and Pb isotopes as a way of fingerprinting geochemically between different Australian regions, and for comparison with other continental PSAs. This part also reviews previous studies that aimed at geochemically fingerprinting the Australian regolith by referring also how these studies were applied to reconstruct past environmental conditions.

Thorough and constructive reviews by J. Brendan Murphy and an anonymous reviewer improved greatly this paper. I would like to acknowledge (in alphabetical order) Mark Dekkers, John Geissman, Gabriel Gutierrez-Alonso, Stephen Johnston, Cor Langereis, Patrick Meere, Tatsuki Tsujimori, and Rob van der Voo for endless discussions about the reconstruction. This paper is a contribution to UNESCO's IGCP 648: Supercontinent Cycles & Global Geodynamics project and it is dedicated to the career of Rob van der Voo. This work has been funded by a post-doctoral fellowship from The Netherlands Research Centre for Integrated Solid Earth Sciences (ISES), a fellowship for overseas researchers from the Japan Society for Promotion of Science (JSPS) (grant P16329) and a MEXT/JSPS KAKENHI Grant (JP16F16329) and a Ramon y Cajal Fellowship from the Spanish Ministry of Science and Innovation. I especially thank all the beats Charles Robert Watts has ever made. The author declares no competing interest., The supercontinent cycle explains how landmasses amalgamate into supercontinents that dismember after a ~ 100 Myr tenure in a quasi-periodic manner. Supercontinents are thought to be rigid superplates whose formation controls many of the Earth's secular variations, from long-term climate trends to global mantle circulation. Pangea, the latest continental superplate, formed ~330 Ma, began to rift ~240 Ma, finally broke-up ~200 Ma, is generally considered the template for all previous supercontinents. The existence of Pangea as a superplate at ~330 Ma is inconsistent with: (i) the kinematic constraints of the continent-continent collision that became progressively younger westwards and it only ended in the early Permian times in its westernmost side; (ii) the widespread ‘post-orogenic’ magmatism in the core of Pangea and the hot high-pressure metamorphism in the Paleotethys; and (iii) the global paleomagnetic database that shows paleolatitudinal overlaps between the participating continents, and significant vertical axis rotations in the core of Pangea between 330 and 270 Ma, which suggests >1500 km of shortening and extension. Here I present a tectonic reconstruction that reconciles the paleomagnetic and geological discrepancies. In this model, after the initial amalgamation of Pangea as a landmass, the comprising plates kept on interacting between each other and the asthenosphere during the late Carboniferous and early Permian (320–270 Ma) instead of being a rigid plate. After that and concomitant with a plate reorganization, Pangea finally established as a superplate for a brief period of, Netherlands Research Centre for Integrated Solid Earth Sciences (ISES), Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science P16329 Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research (KAKENHI) JP16F16329 Spanish Government

Organic matter (OM)-hosted pores are important constituents of the pore system of black shales and play a crucial role in determining their methane adsorption capacity and porosity. OM-hosted pores are generally observed and described with scanning electron microscope (SEM) on Ar ion-milled surfaces. However, SEM imaging is not able to reliably distinguish OM types and relate the observed pores to specific macerals. Partly because of this inability to relate organic pores to macerals, the evolution of organic porosity during thermal maturation remains poorly understood. In this paper, we review the petrographic characteristics of dispersed organic matter (DOM) in black shales under the SEM. Organic petrographic classification of DOM developed for reflected-light microscopy is so far the most practical method when describing DOM in black shales under the SEM because this classification has information on the origin of DOM. Therefore, correlative microscopy (combination of reflected-light and electron microscopy) is the most effective method to identify both OM types and OM-hosted pores. This method, however, is not readily available to most researchers. Although identifying OM on the basis of SEM observations is a challenging task, it is achievable provided there is a good understanding of the studied shales, especially their thermal maturity and original OM composition. Therefore, the overall objective of this paper is to review petrographic characteristics of DOM in black shales under the SEM to provide some guidelines for identifying DOM from SEM observations. We also review factors that control the formation and preservation of OM-hosted pores. OM-hosted pores consist of primary and secondary organic pores. Primary organic pores are pores inherited from the biological structure of the original OM. Secondary organic pores develop during hydrocarbon generation and expulsion from oil-prone OM and are hosted by solid bitumen or pyrobitumen. The development of secondary organic pores is controlled by thermal maturity and OM type, and their preservation is subject to thermal maturity, OM content, and mineralogical composition. The presented view of the evolution of micropore and mesopore characteristics of OM with thermal maturity is based on data from the literature. The specific surface area and pore volume of OM in black shales follow a parabolic pattern with increasing thermal maturity (quantified via vitrinite reflectance, Ro). The initial increase reflects development of OM-hosted pores, and the subsequent decrease is due to denser stacking of aromatic units in the macromolecular structure of OM, with maximum values (specific surface area ~ 300 m2/g and pore volume ~ 0.3 cm3/g) reached at Ro values in the 2.5–3.5% range. The contribution of OM-hosted pores to the pore characteristics of black shales depends on OM content, OM type, and thermal maturity.

In the last half-century, geoscience research has advanced due to multidisciplinary technologies, among which Information and Communication Technology (ICT) has played a vital role. However, scientifically organizing these ICTs toward improving geoscience measurements, data processing, and information services has encountered tremendous challenges. This paper reviews a profound revolution in geoscience that has resulted from the Geospatial Sensor Web (GSW), serving as a new cyber-physical spatio-temporal information infrastructure for geoscience on the World Wide Web (WWW). In contrast to previous experiment-based and sensor-based paradigms, the GSW-based paradigm is able to accomplish the following: (1) achieve integrated and sharable management of diverse sensing resources, (2) obtain real-time or near real-time and spatiotemporal continuous data, (3) conduct interoperable and online geoscience data processing and analysis, and (4) provide focusing services with web-based geoscience information and knowledge. As a benefit of the GSW, increasingly more geoscience disciplines are enjoying the value of real-time data, multi-source monitoring, online processing, and intelligence services. This paper reviews the evolution of geoscience research paradigm to demonstrate the scientific background of GSW. Then, we elaborates on four key methods provided by GSW, namely, integrated management, collaborative observation, scalable processing and fusion, and focusing service web capacity. Furthermore, current GSW prototypes and applications for environmental, hydrological, and natural disaster analysis are also reviewed. Moreover, four challenges to the future GSW in geoscience research are identified and analyzed, including integration with the Model Web initiative for sophisticated geo-processing, integration with humans for pervasive sensing, integration with Internet of Things (IoT) to achieve high-quality performance and data mining, and integration with Artificial Intelligence (AI) to provide smart geoservices. We have concluded that GSW has become an indispensable cyber-physical infrastructure, and will play a greater role in geoscience research and application.

The tight sandstones are characterized by low porosity, low permeability, complex pore structure and strong heterogeneity due to the extensive diagenetic modifications they experienced. Understanding of the impact of diagenetic alterations on reservoir quality is crucial to the hydrocarbon exploration and production in tight sandstones. Diagenetic facies, which is the comprehensive description of the diagenesis and diagenetic minerals, determines the formation and distribution of sweet spot. By correlating the diagenetic facies to well log responses, the subsurface distribution of porosity and permeability can be predicted. However, the prediction of diagenetic facies and reservoir quality via well logs in tight sandstones remains a challenging task. This paper critically reviews the impact of diagenesis and diagenetic minerals on reservoir quality in tight sandstones, and establishes a model for prediction of diagenetic facies via well logs, as assessed from peer reviewed papers in the literature as well as from the authors' personal experiences. This review begins with reviewing the impacts of compaction, cementation, dissolution and various types of diagenetic minerals on reservoir quality evolution. The definition and classification schemes of diagenetic facies are then discussed, and the reservoir quality as well as diagenetic evolution sequence of various diagenetic facies is summarized. The same diagenetic facies commonly display similar compositional and textural attributes, matrix and cement, as well as porosity systems. The well log responses (GR, AC, DEN, CNL, and RT) of various diagenetic facies are summarized by the calibration of log values with cores and related thin sections. By translating the diagenetic facies to conventional well logs, a predictable model, which can be used for subsurface reservoir quality prediction, is established. Then the theory of ECS logs is reviewed, and the application of ECS logs in diagenetic facies evaluation is discussed. At last, the quantitative characterization for various type and degree of diagenesis is reviewed, and the subsurface diagenetic facies is predicted by quantitative calculation of the compactional porosity loss, cementational porosity loss and dissolution porosity content via well logs. Correlating the diagenetic facies to well logs provides a powerful tool to predict the distribution of high quality reservoirs in tight sandstones. This review will provide insights into the reservoir quality evaluation and sweet spot prediction via well logs in tight sandstones.

Heat extraction from the geothermal reservoir is sensitive to reservoir properties, operating parameters and coupling among various processes. Due to complex reservoir structure, heat extraction performances and flow field behaviour in geothermal reservoirs are very different than the small scale laboratory model experiments. In recent past, significant progress in reservoir scale numerical modeling has been made for quantification of challenges in geothermal energy system development. In this paper, a comprehensive review of state of the art geothermal reservoir modeling for heat extraction is presented. Various numerical tools and approaches such as the finite difference method, finite element method, finite volume method, etc. to model the geothermal reservoir in the last four decades are discussed. The thrust of this paper is on a critical review of individual evaluation of coupling among all possible processes that are thermo, hydro, mechanical, and chemical processes on heat extraction performance. Future directions in developing better understanding on geothermal reservoir systems are proposed.

The present paper reviews a number of geophysical and geological datasets acquired in recent and less recent times on the modern Messina Strait, aiming at reconstructing the sedimentary dynamics of this complex system. In a second paper, the results achieved with the present study are used as proxy for interpreting the analogue lower Pleistocene succession cropping out along the margins of the modern strait. The tide-dominated Messina Strait separates the Italian peninsula and Sicily in the central Mediterranean Sea. This 3-km-wide marine passageway is governed by bi-directional tidal currents flowing along the strait axis, because of semi-diurnal tidal phase opposition, so that high tide in the Ionian Sea corresponds with low tide in the Tyrrhenian Sea and vice versa. Tidal currents cyclically accelerate passing through the strait central restriction and decelerate towards the strait exits, following reverse directions during each tidal phase. This hydrodynamics generates specific by-pass areas, sediment routes and accumulation patterns in the modern strait, based upon the varying bed-shear stress exerted onto the strait bottom by the converging/diverging M2 tidal waves. Recent multibeam-based investigations on the modern Messina Strait bottom reveal subaqueous morpho-bathymetric features, which allow a number of areas with specific morphologic characters and sedimentary processes to be identified: (i) the ‘strait-centre zone’ is the narrowest and shallowest by-pass sector, where the tidal currents reach their maximum strength eroding and scouring the substrate. (ii) Towards NE and S, two larger ‘dune-bedded zones’ occur. Here, clastic sediments transported as bed load and in suspension are accumulated and continuously reworked forming characteristic bedform fields, whose features reflect complex current patterns due to a strong tidal asymmetry. (iii) The ‘strait-end zones’ represent distal depositional areas, where decelerating currents rework fine-grained smaller moribund dunes. (iv) The ‘strait-margin zones’ are diffusely characterised by mass-wasting processes along the steepest sublittoral sectors, where sediment instability are caused by earthquakes or sea storms. Fan-deltas prograde from the gentler-sloping coastal segments, represent the main sediment entry points with episodic, high-magnitude discharge and are influenced by the tidal circulation only along their delta-front parts. However, a dogmatic zone partition, based on a ‘mutually-evasive’ mechanism of sediment distribution and consequent decrease in the transport capacity towards the strait ends is not everywhere applicable to the Messina Strait sedimentary dynamics. The examination of measured tidal ellipses reveals that although flood and ebb tidal currents are approximately equal in speed, they are collinear only across the narrowest zone, being separated as the strait enlarges. This flow separation has possibly generated two main populations of flood and ebb bedforms, which migrate at high angle and with reverse direction in the two dune-bedded zones of the strait. Moreover, because of a strong water-mass stratification due to a marked difference in salinity, the denser flood constituent dominates over the lighter ebb current. As a consequence, the largest dunes observed in both the strait opposite depositional areas have northward-oriented lee faces, whereas superimposed smaller dunes have southward-oriented fronts, reflecting flood and ebb tidal constituents, respectively. Erosional features in the central sill, uncharacteristic bedforms having orientations not explained by modern currents and coarser grains in some places implying thresholds of motion larger than the modern currents all suggest that different, most likely, larger currents, probably occurred at some point in the past. It is suggested here that these features reflect an early stage of strait connection, during the initial sea-level rise after the Last Glacial Maximum. The data reviewed in the present work summarise the complex sedimentary dynamics of the modern Messina Strait and allow a comparative analysis of the ancient strait exposed along the modern margins, also suggesting insights for other examples of tidal straits developed under similar oceanographic conditions.