ALBERT

Description: This paper presents a summary of palynologic data for Pennsylvanian age coal beds in the Appalachian Basin, discussed primarily from a biostratigraphic perspective. Coal bed palynofloras of Lower Pennsylvanian through Early Permian age are compared and correlated with miospore assemblage zones established for western Europe, and the Eastern Interior (Illinois) and Western Interior Basins of the mid-continent USA.Lower Pennsylvanian palynofloras, which are dominated by lycopsid spores, are correlative with the Langsettian of western Europe and the Morrowan of the Eastern and Western Interior mid-continent USA Basins. Stratigraphically useful palynotaxa include Dictyotriletes bireticulatus, Radiizonates striatus, Schulzospora rara, Granasporites medius, Laevigatosporites minor and Endosporites globiformis.Middle Pennsylvanian palynofloras change through time, being lycopsid dominant in the lower part and more heterogeneous in the middle and upper parts with increased contributions from other Pennsylvanian plant groups. They are correlative with the Duckmantian, Bolsovian and Asturian of western Europe and the Atokan and Desmoinesian of the Eastern and Western Interior mid-continent USA Basins. Stratigraphically useful palynotaxa include Secarisporites remotus, Microreticulatisporites sulcatus, Vestispora fenestrata, Triquitrites sculptilis, Laevigatosporites globosus, Radiizonates difformis, Torispora securis, Triquitrites minutus, Mooreisporites inusitatus, Murospora kosankei, Thymospora pseudothiessenii and Schopfites dimorphus.Upper Pennsylvanian and Lower Permian coal beds in the Appalachian Basin, in contrast to their Lower and Middle Pennsylvanian counterparts, are strongly dominated by tree fern spore palynotaxa. Palynofloras correlate with the Stephanian and Autunian of western Europe and the Missourian, Virgilian and Wolcampian of the Eastern and Western Interior mid-continent USA Basins.

Description: The chalk porosity plays a decisive role in the transport of solutes and heat in saturated chalk. From a geological point of view, there are at least two types of porosities: the porosity of pores corresponding to the micro-spaces between the fossil coccoliths that form the chalk matrix, and the porosity due to the micro- and macro-fractures (i.e., secondary porosity). For groundwater flow, the fracture porosity is a determining factor at the macroscopic scale. The multi-scale heterogeneity of the porous/fractured chalk is inducing different effects on solute and heat transport. For solute transport considered at the macroscopic scale, tracer tests have shown that the ‘effective transport porosity’ is substantially lower than the ‘effective drainable porosity’. Moreover, breakthrough curves of tracer tests are showing an important influence of diffusion in a large portion of ‘immobile water’ (‘matrix diffusion’) together with quick preferential advection through the fractures. For heat transport, the matrix diffusion in the ‘immobile water’ of the chalk is hard to distinguish from conduction within the saturated chalk.

Description: The vast majority of extrusive carbonatites are calcitic rocks which may be confused with sedimentary limestones, thus requiring a disambiguation criterion. Extrusive carbonatites are classified based on quantitative criteria that tend to avoid genetic mechanisms. Carbonatite nomenclature is in progress but regulated by the IUGS norm for igneous rocks. Carbonate sedimentary rock nomenclature is mainly regulated by the Dunham (1962), Embry & Klovan (1971) and Sibley and Gregg (1987) classification systems. These limit the description of rock types from various depositional mechanisms and makes comparison with sedimentary rocks difficult. Igneous and sedimentary carbonate rocks display no apparent differences in the field and at meso-micro-scale. They may be layered, massive crystalline or show discrete clasts in a matrix which make both rock-types resemble each other. The study analyses situations in which classification inconsistencies are most common. Adopting these guidelines may increase confidence, reliability, and value in the petrographic classification of igneous and sedimentary lithologies. This study poses a challenging target. Can igneous carbonate rocks be classified using the same approach used for sedimentary carbonate rocks and vice versa? So far, the scheme chosen was arbitrary or limited to the aim of the study being undertaken. The authors start an unexperienced dialogue for the first time between volcanologists and sedimentologists by examining a range of sedimentary and volcaniclastic rock textures which may resemble each other.

Description: Coastal ecosystems consist of diverse habitats, such as reed beds, salt marshes, mangrove swamps, tidal flats, river deltas, seagrass fields, coral reefs, sandy/rocky-shore beaches and other habitats that harbour biodiversity. The Great East Japan Earthquake of March 2011 caused severe damage to one-third of the fishing communities along the Pacific Ocean of northeastern Japan. Coastal species, such as seagrasses, function as nursery areas for commercially important species. Coastal ecosystems provide natural infrastructure for the prevention and reduction of hazardous events, a process known as ecosystem-based disaster risk reduction (Eco-DRR). The preparation of topographic and thematic maps of coastal marine environments is essential to establish and visualise the concept of Eco-DRR. Experience gained following the Japanese earthquake, as well as examples from Indonesia and Thailand in the wake of 2004 Indian Ocean tsunami showed that Eco-DRR is an affordable and sustainable approach. Dissemination of habitat maps should be further promoted as a means to ‘Build Back Better’. To scale up and promote Eco-DRR, scientists must work in a transdisciplinary manner and engage with society through understanding the roles of ecosystems by monitoring and analysing, providing solutions and raising the awareness of community and policy makers, enabling them to better implement Eco-DRR.

Description: Spiti valley is located in the Trans-Himalayan terrain of India, from where non-geometric microliths have been discovered. While the Siwalik Hills have been subjected to extensive prehistoric surveys, this is the first evidence of lithic tools discovered in the Trans-Himalayan region of Himachal Pradesh, India. Due to its topographic and intense climatic features, the Trans- Himalayan region has generally been regarded as a barrier since prehistoric times. However, Dzamathang cannot be considered as an isolated site in the Trans- Himalayas. In fact, in the adjoining areas of Ladakh, Tibet and Nepal, similar lithics have been reported from several sites and assigned to the Middle and Upper Palaeolithic. The discovery of this site suggests that the Trans Himalayan zone may have acted as a possible route instead of a barrier during human migration. Large numbers of lithics have been recovered in the Dzamathang area of Spiti Valley. Based on the collection of the artefacts from the surface, this article tries to understand the geological and geographical setting of the area, particularly concerning prehistoric settlements in the Trans-Himalayas. This assemblage consists of assorted artefacts which includes a unifacial chopper, microlithic cores, flakes, blades, bladelets, burin, and a large amount of debitage fragments. The majority of artefacts are on quartzite or quartzarenite. Future surveys will be targeted at recovering primary context sites for excavations and absolute dating.

Description: Detrital gold fulfils the criteria of chemical inertia and physical durability required by indicator minerals but it has not found wide application in this role because it may be formed in different deposit types. This problem is soluble, because the generic compositional features of hydrothermal gold differ according to mineralization environment. The wide distribution of gold as a minor component of mineralization where other commodities are the principal exploration target extends the potential of an indicator methodology based on detrital gold to beyond the search for gold itself. Here we highlight how distinctive gold compositional signatures derived from alloy composition and deposit- specific suites of mineral inclusions could contribute to exploration for Cu–Au porphyries, redox-controlled uranium mineralization and ultramafic-hosted PGE mineralization. Future refinement this approach will focus on establishing the spatial distribution of elements at trace levels within gold particle sections using ToF-LA-ICP-MS and application of Exploratory Data Analysis to the resulting datasets. This approach is in its infancy, but aims to develop a classification algorithm useful to researchers irrespective of their previous experience. A pilot study has shown that random forests provide the best approach to establishing gold particle origins.

Description: The North China craton is encircled by four successive triple-conjugated rifts, which are respectively centers of large igneous provinces (LIPs) of bimodal compositions, i.e., Xiong'er rift (south, ca. 1.78 Ga Taihang LIP), Yanliao rift (north, ca. 1.32 Ga Yanliao LIP), Xuhuai rift (east, ca. 1.23 Ga Licheng and ca. 0.92 Ga Dashigou LIPs), and Langshan rift (west, ca. 0.82 Ga Qianlishan LIP). These rifts are genetically related with their contemporaneous LIPs based on their consistent geometry. Spatial migration of these rifts and LIPs indicates their propagation from along one marginal side to the opposite side of the craton, which may results in the sequential breakup of the proto-North China craton from one side to another during 1.8-0.8 Ga. However, the observation that the lithosphere under the LIP-associated rift regions is less destructed (decratonized) in the Mesozoic indicates a possible role of LIPs in strengthening intracratonic steady state. This study shows that LIPs may change craton stability in either direction.

Description: Compositional studies of natural gold usually have a geological focus, but are also important in archaeological provenancing. Both methodologies rely on compositional comparison of two sets of samples, one of which is geographically constrained. Here we describe how experiences in gold characterization resulting from geological studies are relevant to archaeology. Microchemical characterization of polished sections of natural gold identifies alloy compositions, alloy heterogeneity and mineral inclusions. Gold from all deposit types shows Cu and Sn values much lower than those recorded during numerous studies of artefacts. Inclusions in artefact gold include various Cu- and Sn-bearing compounds which indicate specific high temperature reactions that could ultimately illuminate the conditions of (s)melting. The use of LA-ICP-MS to generate a wide range of elemental discriminants for provenance studies may be compromised by alloy adulteration and/or unrepresentative analysis of natural/artefact alloys, which are commonly highly heterogeneous at the micron scale. Geological studies normally characterize only the earliest-formed (hypogene) alloy, whereas archaeology-focused studies should entail analyses of bulk alloy compositions and impurities that may be incorporated during (s)melting. Isotopic-based provenancing alleviates many of these problems but, to date, generates regional rather than locality-specific targets. A dual isotopic–compositional approach is recommended.

Description: This review focusses on the recognition of volcanic ash occurrences in marine sediment cores and on using their appearance and properties to deduce their origin. Widespread marine tephra layers are important marker horizons for both volcanological as well as general geological investigations. We describe ash detection by visual inspection and logging of sediment cores. Ash layer structure and texture, particle morphologies and lithological compositions of primary volcanic deposits are summarized and processes modifying them are discussed, both natural processes acting on and in the seafloor, i.e., erosion and bioturbation, and man-made modifications during drilling/coring and core preparation. We discuss primary emplacement processes of marine fall and flow tephra deposits derived from either subaerial or submarine sources in order to identify distinguishing properties. We also elaborate on processes generating secondary, resedimented volcaniclastic layers such as submarine landslides and shelf erosion as well as fluvial input and ice-rafting, and how they can be distinguished from primary volcaniclastic deposits, which is essential in tephrostratigraphy. Finally, methods of tephra correlation between cores and on-land deposits/volcanoes are illustrated because they allow us to extend the 1-D information from single cores to 3-D distribution and facies changes of tephras and to bridge the land-sea gap.

Description: New 40Ar/39Ar data from dykes intruded into Sverdrupfjella and Ahlmanryggen, Dronning Maud Land, Antarctica, indicate that dyke emplacement commenced at c. 207 Ma and lasted until c. 178 Ma. Whereas the ages ascribed to the Karoo-age magmatism contributing to Gondwana breakup are typically inferred as being c. 182 Ma, the data indicate that ages older than c.192 Ma in the broader Karoo Province are restricted to western Dronning Maud Land, Antarctica, indicating the locality where breakup was initiated. Limited palaeomagnetic data from c. 178–185 Ma dykes combined with published palaeomagnetic data from similar-aged dykes in Vestfjella and the Ferrar Province, suggest that Antarctica had already drifted/rifted significantly away from southern Africa from c. 207 to c. 180 Ma, earlier than previously thought. The data, if correct, require a re-evaluation of the ages ascribed to ocean-floor anomalies used to constrain reconstructions of Gondwana and may provide insight into the history of microcontinental blocks including the Falkland Islands, Haag nunataks, Ellsworth–Whitmore block and Maurice Ewing Bank.Supplementary material: Petrography, Ar isotope data from all samples and summary of ages are available at https://doi.org/10.6084/m9.figshare.c.5612838