Geological Series Research Articles

Evidence for active upper mantle flow in the Atlantic and Indo-Australian realms since the Upper Jurassic from hiatus maps and spreading rate changes

Histories of large-scale horizontal and vertical lithosphere motion hold important information on mantle convection. Here, we compare continent-scale hiatus maps as a proxy for mantle flow induced dynamic topography and plate motion variations in the Atlantic and Indo-Australian realms since the Upper Jurassic, finding they frequently correlate, except when plate boundary forces may play a significant role. This correlation agrees with descriptions of asthenosphere flow beneath tectonic plates in terms of Poiseuille/Couette flow, as it explicitly relates plate motion changes, induced by evolving basal shear forces, to non-isostatic vertical motion of the lithosphere. Our analysis reveals a timescale, on the order of a geological series, between the occurrence of continent-scale hiatus and plate motion changes. This is consistent with the presence of a weak upper mantle. It also shows a spatial scale for interregional hiatus, on the order of 2000–3000 km in diameter, which can be linked by fluid dynamic analysis to active upper mantle flow regions. Our results suggest future studies should pursue large-scale horizontal and vertical lithosphere motion in combination, to track the expressions of past mantle flow. Such studies would provide powerful constraints for adjoint-based geodynamic inverse models of past mantle convection.

Russian Geomorphological School: 100 Years of Development

In connection with the recent centennial (2018) of Russian geomorphology, we examined the history of the origin and development of geomorphological knowledge in this country. We analyzed the main stages of the formation of national geomorphology: from the prehistory (17th‒18th centuries) and the incubation period (19th‒early 20th centuries) to an intense development in the Soviet period (most of the 20th century) and the modern stage. We distinguished the main driving forces of this process: the enormous size of the country and the corresponding diversity of landscapes, a high economic need for development of natural resources, and a need for effective systematization of knowledge in the field of Earth sciences. We also emphasized the continuity and close connection of the development of geomorphology in Russia/USSR and in other countries. Particular attention was paid to the Russian geomorphological schools concentrated in major educational and scientific centers in Moscow, St. Petersburg, Irkutsk, Kazan, Tomsk, etc. National researchers of these schools promote important scientific fields, such as structural geomorphology (morphotectonics), climatic (exogenous) geomorphology, geomorphological systematics and cartography, evolutionary geomorphology, morphometry, dynamic and engineering geomorphology, environmental, social geomorphology, etc. Separately, we mentioned the contribution to the Russian geomorphological science by famous scientists: P.A. Kropotkin, V.V. Dokuchaev, D.N. Anuchin, M.M. Tetyaev, Ya.S. Edelstein, I.S. Shchukin, K.K. Markov, S.S. Schulz, I.P. Gerasimov, Yu.A. Meshcheryakov, D.A. Timofeev, O.K. Leontyev, Yu.G. Simonov, N.A. Florensov, G.F. Ufimtsev, A.N. Lastochkin, and many others. Finally, we emphasized that today Russia’s geomorphology has entered a new stage of development corresponding to current world trends: the study of inaccessible terrain (submarine, subglacial, extraterrestrial), digital modeling based on GIS technologies, and integration with other disciplines of the geological and geographical series.

Continent-scale Hiatus Maps for the Atlantic Realm and Australia since the Upper Jurassic and links to mantle flow induced dynamic topography.

Interregional geological maps hold important information for geodynamic models. Here, we use such maps to visualize major conformable and unconformable contacts at interregional scales and at the level of geologic series from the Upper Jurassic onward across North and South America, Europe, Africa and Australia. We extract hiatus information from these paleogeological maps, which we plot in a paleogeographical reference frame to link the maps to the plate and plume modes of mantle convection. We assume that interregional patterns of hiatus surfaces are proxy records of continent-scale mantle-induced vertical motion of the lithosphere. We find significant differences in the distribution of hiatus across and between continents at the timescale of geologic series, that is ten to a few tens of millions of years (Myrs). This is smaller than the mantle transit time, which, as the timescale of convection, is about 100-200 Myrs. Our results imply that different timescales for convection and topography in convective support must be an integral component of time-dependent geodynamic Earth models, consistent with the presence of a weaker upper mantle relative to the lower mantle. Additional geological constraints together with interregional geological maps at the resolution of stages (1-2 Myrs), are needed to assist in future geodynamic interpretations of interregional geologic hiatus.

Geophysical study of Hammam Sidi Maamar geothermal site in Central Tunisia for sustainable development

Geophysical methods provide important help to investigate geothermal reservoirs. They permit to delineate deep and near surface structuring and to appreciate fluid circulation. In this study, we performed an integrated geophysical study using regional seismic reflection profiles and local Electrical Resistivity Tomography (ERT) data analyses to identify the relation between faults and specific geothermal pathways around Hammam Sidi Maamar thermal spring site in Hajeb Layoun area (Central Tunisia). The proposed geological model performed from seismic reflection composite sections reveals the geometry in depth series of the Lower Cretaceous from the recharge zone (Jebel Mrhila mountain) to the emergence area of Hammam Sidi Maamar (Jebel Baten Damous mountain) and traces the path of the thermal water, from its recharge area till surfacing, in order to propose a new suitable intake location with higher flow and temperature. The results of seismic and ERT data analysis confirm that the Hammam Sidi Maamar geothermal site is tectonically related to the junction of the NE-SW Baten Damous fault corridor and the NW-SE to E-W northern fault corridor of Hajeb Layoun graben. The water is charged from Lower Cretaceous (Hauterivian to Aptian) outcrop series in Jebel Mrhila Mountain to the West. It flows into the carbonate reservoir below the Hajeb Layoun-Jelma Plain, where the Lower Cretaceous reservoirs are reaching more than 2500 m deep. The reservoir geologic layers show ascent geometry towards Jebel Zaouia Mountain then they sink into the Hajeb Layoun Graben to the East. The thermal water rises to surface thanks to the deep faults that affect the Lower Cretaceous reservoir and the geologic series above. High resolution Electrical Resistivity Tomography panels, we carried out in Hammam Sidi Maamar geothermal site, allowed to locally identify the faulting architecture which controls the flow of hot water. Firstly, filtering and processing of ERT data were performed. 2D ERT modeling, mapping and 3D ERT view interpretation, were also performed to more understand the local tectonic/geothermal flow setting. Finally, to identify the prominent site for lateral and vertical geothermal flow plumes, we propose to drill 50 m–60 m intake well associated with a tectonic junction of the NE-SW Baten Damous fault corridor and the NW-SE to E-W Hajeb Layoun graben fault.

GEOECOLOGY – UNITY OF GEOLOGICAL AND GEOGRAPHICAL SCIENCES

This article reviews the theory of Geoecology as a modern science in the geological and geographical series. There are propositions that geography of underground spaces will arise in the future due to intensive human use of the geological space, including the construction of intercity and international underground transport connections, large-scale underground urbanization, construction of underground industrial facilities, establishment and maintenance of underground conservation areas and tourism-and-recreation spaces, etc. The boundaries of the geographical shell are defined, the existing concepts of Geoecology (states, changes, and techniques) are briefly described and grouped. Special focus is on the geochemical aspects of the theoretical foundations of geoecological research. The following main reasons for the selection of the geological-geographical approach to Geoecology were defined: expansion of the geographical shell boundaries beyond the Earth’s surface; the penetration of life into all external geospheres, the existence of a deep biosphere; the manifestation of geodynamic processes on the earth’s surface, including the release of gases and emanations in zones of active faults and fractures on the Earth’s crust; the basic role of rocks in landscape formation (underground landscapes, sink and source of subsurface and underground water, soiland relief formation); utilization of underground spaces by humans. The two most important ecological and geochemical aspects of the geological-geographical approach are named. The first one has to do with the qualitative and quantitative chemical (elemental) composition of geospheres and components of geosystems, and the second one with the geochemical processes that generate the diversity of geochemical relationships both within each individual geosystem, and between different geosystems.

Analysis of geological hiatus surfaces across Africa in the Cenozoic and implications for the timescales of convectively-maintained topography

Geological maps are a powerful but underutilized tool for constraining geodynamic processes and models. Unraveling the Cenozoic elevation history of Africa and distinguishing between competing uplift and subsidence scenarios is of considerable interest to constrain the dynamic processes in the mantle beneath the continent. Here, we explore continental-scale geological maps, and map temporal and spatial patterns of geological contacts, assuming that interregional-scale unconformable contacts (hiatus surfaces) on geological maps yield proxy records of paleotopography and vertical motion. We found that significant differences in the spatial extents of interregional-scale hiatus surfaces exist across Africa at the timescale of geologic series. A significant expansion of total unconformable area at the base of the Miocene strongly suggests that the Oligocene was a period of uplift in most of Africa. In southern Africa there is a complete absence of marine sediments in both the Oligocene and Pleistocene. This pattern suggests that southernmost Africa reached a high elevation in the Oligocene, subsided in the Miocene–Pliocene, and has been high again since the latest Pliocene or Pleistocene. Our hiatus mapping results support a dynamic origin of Africa’s topography. In particular, they point to elevation changes at the timescale of geologic series (ten to a few tens of millions of years), which is considerably smaller than the mantle transit time. The timescale for elevation changes in Africa is, thus, comparable with the rapid spreading in the South Atlantic, which have been geodynamically linked to African elevation changes through pressure-driven upper mantle flow.

Improving Hydric Soil Identification in Areas Containing Problematic Red Parent Materials: a Nationwide Collaborative Mapping Approach

Hydric soil identification utilizes diagnostic morphologic features, including iron transformations, resulting from anaerobic conditions. However, soils derived from some red parent materials (RPM) fail to develop characteristic hydric soils morphologies, confounding hydric soil and wetland delineation. Laboratory and field methods addressing resistant RPM soils exist, but application remains limited by uncertainty regarding problematic RPM distribution. In response, a collaborative effort (>50 participants) documented problematic RPM distribution across the contiguous United States. Specifically, >1100 samples from >450 locations underwent laboratory analysis using the Color Change Propensity Index to identify problematic RPM soils. Geospatial analysis linked verified problematic soils with associated geologic units and soil series, generating maps of RPM distribution. Potential problematic RPM was identified in the Northeast and Mid-Atlantic, Great Lakes, South-central, and Desert Southwest-Western Mountains (problematic RPM regions herein), encompassing diverse groups of soils and parent materials. Despite the observed variability in soil characteristics, results suggest that problematic RPM was consistently derived from sedimentary, hematite-rich red bed formations developed where deposition of terrestrial sediments occurred in near-shore, marginal-marine environments. Understanding problematic RPM soils distribution promotes the appropriate application of existing hydric soil field indicators, including F21 – Red Parent Material, thus improving approaches to hydric soil identification and wetland management.

Geochemistry of late miocene-pleistocene basalts in the Phu Quy island area (East Vietnam Sea): Implication for mantle source feature and melt generation

Geochemistry of late miocene-pleistocene basalts in the Phu Quy island area (East Vietnam Sea): Implication for mantle source feature and melt generation

Indirect geophysical characterization of geohazards in mantled karst environments in the Ebro Basin

Karst hazards in the central Ebro Basin are related to subsidence and collapses owing to evaporitic rocks located several tens of metres below the surface. In this type of karst (mantle karst) cavities propagate upwards through a non-soluble rock, in this case Quaternary alluvial deposits. The typical geological series comprises a heterogeneous alluvial unit underlain by a soluble, mainly gypsiferous, substratum and several water tables that usually present high conductivity variations. The highest concentration of karstic evidence is identified along the fluvial flood plain of the Ebro River where clayey deposits dominate at the surface. These boundary conditions produce complex environments for the evaluation of geophysical data related to i) karst activity, ii) the presence of cavities below the water table and within the substratum and iii) the variable sedimentary architecture of fluvial deposits. During the past ten years different geophysical techniques have been used in order to characterize karst hazards in the Central Ebro Basin. These experiences have enabled the evaluation resolution, discrimination characterization and finding of karstic evidence using different approaches. The main success in the application of these geophysical techniques has been the quantification of karst hazards from the record of subsidence processes through changes in density, magnetic susceptibility, apparent conductivity and structure of the alluvial deposits. However, the identification of cavities below the alluvial series still represents a serious handicap wing to nonunivocal interpretations and low resolution or penetration of geophysical techniques.

Roadside Geology of Georgia by Pamela J. W. Gore and William Witherspoon. Mountain Press, Missoula, MT; www.mountain-press.com. 347 pages; 2013; $24 plus postage (softbound).

Roadside Geology of Georgia, the latest addition to the Roadside Geology Series, reflects Mountain Press's recent trend to offer higher quality guides with more information and better illustrations...

The conodont Iapetognathus and its value for defining the base of the Ordovician System

Nicoll et al. (1999, Brigham Young University Geology Studies 44, 27–101) published the taxonomy of species of the ramiform conodont Iapetognathus Landing in Fortey et al. (1982, The Cambrian–Ordovician boundary: sections, fossil distributions, and correlations, National Museum of Wales, Geological Series No. 3, Cardiff, 95–129) and its ancestor Iapetonudus Nicoll et al., 1999. Cooper et al. (2001, Episodes 24, 19–28) used the First Appearance Datum of Iapetognathus fluctivagus Nicoll et al., 1999 to mark the base of the Ordovician System at Green Point, Newfoundland. Terfelt et al. (2012, Lethaia 45, 227–237) re-evaluated Iapetognathus at Green Point and made several taxonomic and stratigraphic conclusions, nearly all of which we refute herein.

Digital Compilation of 1∶1 000 000 Geological and Geophysical Map Series of China and Adjacent Regions on MapGIS Platform

Digital Compilation of 1∶1 000 000 Geological and Geophysical Map Series of China and Adjacent Regions on MapGIS Platform

British geological maps that guided excavation of military dug-outs in Belgium during World War I

Abstract Between November 1917 and June 1918, 12 maps at 1:10 000 scale of western Belgium (part of the British-occupied sector of the Western Front) were printed for the British army. These classified the ground according to its suitability for the excavation of dug-outs. Compilation was largely by the Welsh-born Australian T. W. Edgeworth David, using pre-war Belgian geological maps and data from c . 1000 British and Belgian boreholes. Lithostratigraphical units were coloured primarily in shades of red to indicate relatively ‘good’ (dry) strata, contrasted with ‘bad’ (wet) units coloured in shades of blue. The maps constitute the first engineering–environmental geology series to be published for British use, and arguably the first published large-scale engineering geology map series per se . Such little-known innovations in World War I, by British, US, German and Austro-Hungarian military geologists, were further developed in World War II. Wartime expertise consequently provided part of the foundation for the development of engineering geology postwar.

The hydrogeology of Adama-Wonji basin and assessment of groundwater level changes in Wonji wetland, Main Ethiopian Rift: results from 2D tomography and electrical sounding methods

Rise of groundwater level becomes an emerging concern at Wonji irrigation field, Main Ethiopian Rift. An integrated study based on geophysical resistivity methods is conducted at Wonji wetland to understand the link between irrigation water and the shallow aquifer system as well as to confirm the current concern of groundwater rise. The study was also intended to improve the uncertainty of understanding the hydrogeology of Wonji wetland including the extent and direction of groundwater–surface water interaction. The vertical and horizontal contacts between the different geological series of the Wonji area are resolved with 2D high-resolution geophysical imaging. Results from both VES and 2D tomography show low resistivity layers under Wonji irrigation field with narrow ranges in resistivity variation which corresponds to a homogeneous saturated layer. The geoelectric sections reveal two fault systems running NW–SE and N–S directions which impede lateral groundwater flow. Furthermore, groundwater is converged towards the Wonji irrigation site strained by these fault systems. The geophysical results show strong link between irrigation water and the shallow unconfined aquifer as well as among the local and regional flow systems.

L’ambre albo-cénomanien de la montagne de Lure (Alpes-de-Haute-Provence), outil stratigraphique et paléogéographique

Nodules of fossil resin or amber, first drifted and then deposited in the marine series with cephalopods, were discovered in several areas of High-Provence, in geological series of the Cretaceous system. These areas are located around the Mountain of Lure; amber nodules have been found in the upper Albian (Ongles, Revest-des-Brousses) and in the lower Cenomanian (Saint-Étienne-les-Orgues, Aubignosc and Salignac). These ambers have very homogeneous and characteristic FTIR spectra, making it possible to distinguish them not only from more recent ambers of the upper Cretaceous of Provence (Santonian), but also from tertiary ambers of the Baltic sea. These organic matters in marine environment, brought by the currents and deposited in shallow waters of the Ventoux-Lure area, are in agreement with close emerged grounds, which were set up by the Albo-Cenomanian tectonic movements.

Geological modelling from field data and geological knowledge: Part I. Modelling method coupling 3D potential-field interpolation and geological rules

An original method has been developed to model geology using the location of the geological interfaces and orientation data from structural field. Both types of data are cokriged to interpolate a continuous 3D potential-field scalar function describing the geometry of the geology. Geology contact locations set the position of reference isovalues while orientation data are the gradients of the scalar function. Geometry of geological bodies is achieved by discretising reference isovalues. Faults are modelled using the same method by inserting discontinuities in the potential field. Potential fields can be combined to model realistic, complex geometry: scalar functions representing separate geological series are merged automatically using geological rules to enable fast computation and easy update of interpretation. The methodology has been applied to a wide range of geological contexts including orogenic domains, basins, intrusive and extrusive environments.

Bones and ochre: the curious afterlife of the Red Lady of Paviland

Introduction Part One: William Buckland (1784-1856), an Ancient British Witch, and the Question of Human Antiquity 1. William Buckland (1784-1856) 2. Man among the Cannibalistic Hyena? 3. The Romance of the Witch of Paviland 4. Buckland Accused 5. Man as a Crocodile Superior? 6. The Holy Order of Nature and Society Conclusion: The Red Is No Fossil Man Part Two: William Sollas (1849-1936), a Cro-Magnon Man, and Issues of Human Evolution 7. William Sollas (1849-1936) 8. Ancient Hunters and Their Modern Representatives 9. The Red Is a Cro-Magnon Man 10. Human Evolution as Trunkless Tree 11. The Evolutionary Versus the Historical Model 12. The Moral Authority of Nature Conclusion: Turbulent Times for an Old Lady Part Three: An Interdisciplinary Team, an Early Upper Paleolithic Shaman, and a Definitive Report 13. The Paviland Project and Its Results 14. There is Magic at Work 15. Visualizing Paviland Cave 16. The End of the Red Lady's Story--A Definitive Report? Conclusion: An Unfinished Life Postscript Appendix A: Archaeological and Geological Series Appendix B: Schematized Views of Human Evolution Notes References Index

Mass movements in Great Britain, Geological Conservation Review Series, Vol. 33 By R G Cooper

Mass movements in Great Britain, Geological Conservation Review Series, Vol. 33 By R G Cooper

Ecological Patterns in the Upper Pleistocene and Holocene in the Jebel Gharbi, Northern Libya: Chronology, Climate and Human Occupation

Surveys and test excavations in the Jebel Gharbi have brought to light a large quantity of prehistoric sites indicating intensive human occupation from the Upper Pleistocene to the Holocene. Several radiometric dates (standard 14C, AMS and U/Th) provide a detailed framework of the absolute chronology of the local peopling of the area. Generalised Middle Stone Age archaeological materials represent the earliest term of reference in the geological series. Aterian complexes are well-represented, being widely spread throughout the mountain range and in the lowlands. Lower Later Stone Age, or “Dabban”, artefacts are also attested to both geological and archaeological sequences. Human occupation continued with the Upper and Final Epipalaeolithic (or “Iberomaurusian”) and later, with Capsian and Neolithic groups. Permanent and seasonal water springs and raw material sources influenced settlement strategy and selected areas offered particularly favourable conditions and became intensively occupied.

M. F. Howells British Regional Geology: Wales. British Geological Survey, Keyworth, Nottingham, UK, 2007. 230 pp. Price: £18. ISBN: 978-0-85272-584-9.

As the foreword to this edition in the British Regional Geology series points out, Wales punches well above its weight in terms of the influence on the science of geology in relation to its small area. Some of the periods in the geological column were defined in Wales in the 19th and early 20th century. Understanding of the complex geology of Wales and the Welsh Borderland led to the establishment of the Cambrian and Silurian systems by Adam Sedwick (1835) and Roderick Murchison (1839), respectively. Later, Charles Lapworth (1879) defined the Ordovician system to consist of rocks that had previously been assigned to either the Cambrian or Silurian by Sedwick or Lapworth, and which ever since had been a topic of considerable controversy. Some of the earliest mapping by the Geological Survey took place in South Wales. There were seminal works on the volcanic rocks of north Wales by Harker (1889), and on the evolution of the sedimentary sequences in central Wales in an evolving ‘geosyncline’ by Jones (1938). One of the earliest palaeogeographical reconstructions led to identification of an ancient Ordovician shoreline in the …