The Neogene and Quaternary hinterland basins of the Northern Apennine have been the subject of different tectonic interpretations. Several studies considered these basins as the result of polyphase normal faulting framed in a continuous crustal extensional regime since the middle Miocene. On the contrary, geophysical and geological studies provided evidence of the important role played by out-of-sequence thrusts and backthrusts in the evolution of these basins during a prolongated and intense period of shortening. Here we present an integrated analysis of 2D stacked seismic reflection profiles, stratigraphic and geophysical data from deep exploration wells, gravity data, and published geological and biostratigraphic data for the Valdera-Volterra basin (central Tuscany, Italy). The results support a polyphase and composite evolution of the basin, subdivided into three main phases. During the late Tortonian-Zanclean, the growth of major thrust-related anticlines controlled the evolution of the sedimentary basin. The growth of a syncline determined the creation of accommodation space for the sediments. This main compressional deformation occurred during the Messinian and ended during the Late Zanclean. NE migration of the depocentre during the Early Zanclean was identified, likely possibly due to a differential activity growth between the bordering anticlines. During the Piacenzian, an extensional phase has been recognised, superposed to the previous compressive phase. During the Latest Piacenzian-Early Pleistocene (?), a final compressional phase took place resulting in the positive inversion of the Piacenzian WSW dipping main border fault. Reconstruction of the polyphase tectono-stratigraphic evolution of the Neogene-Quaternary Valdera-Volterra Basin, one of the largest hinterland basin of the Northern Apennines, through the study of 2D seismic sections integrated with published and unpublished geophysical and stratigraphic data from deep boreholes and surface palaeontological samples.image
Stone tools in association with Pleistocene elephant remains were recovered from Pampore, Kashmir, India, in 2000 from channel deposits in the Pampore Member of the Upper Karewa Group of sediments, which are interpreted as Middle Pleistocene in age. In March 2019 the elephant remains were re-examined to establish taxonomy, cause of death and evidence of human intervention, alongside study of the stone tools and age of the site. This paper reports the results of this work. Most of the elephant remains, including skull and tusks, are from a large adult, but at least two other elephants are also represented. Taxonomic analysis shows that the adult belongs to the genus Palaeoloxodon, but with a mix of features not seen in typical Palaeoloxodon skulls from the Indian Subcontinent. Pathology of the skull indicates severe sinusitis, which may have contributed to the death. No cut-marks from butchery were found on the elephant bones, although three elephant bone flakes were identified, linking human intervention with elephants at the site. The small lithic assemblage is in fresh condition with some refitting artefacts, both suggesting minimal post-depositional movement. Most of the artefacts consist of flakes, flake tools and cores, but with several points and blades suggestive of an early Mode 3 prepared core technology. This might indicate a late Middle Pleistocene age for the site. Further dating evidence using amino acid racemisation on elephant tooth enamel is ongoing, but consistent with this age. The association of stone tools with humanly-modified elephant remains is rare, while prepared core technology is currently scarce further north or east in Asia in the late Middle Pleistocene. The significance of the discovery is discussed in the wider context of Middle Pleistocene elephant-human interaction.
In this study, we describe a remarkably well-preserved cranium and stylohyoids of a large elephant from the Middle Pleistocene Pampore Member in the Karewas of Kashmir that was found associated with 87 stone tools. Based on the cranio-dental morphology, we assign the skull to the genus Palaeoloxodon, a lineage of massive elephants that evolved in Africa in the Early Pleistocene, and later dispersed across Eurasia. The skull possesses a combination of plesiomorphic and derived features of Palaeoloxodon, most notably, a broad, expanded frons and a nasal aperture with rounded margins that is characteristic of derived Eurasian Palaeoloxodon; but with an extremely underdeveloped parieto-occipital crest that is reminiscent of the basally branching African species, Palaeoloxodon recki. It is most similar in morphology to the type skull of Palaeoloxodon turkmenicus from Central Asia. The morphology of the stylohyoids is also different from those referred to Palaeoloxodon antiquus from Europe and Palaeoloxodon naumanni from Japan. While the validity of P. turkmenicus has been questioned in the past, this new specimen from Kashmir provides a strong case for a Middle Pleistocene species of Palaeoloxodon in Central and South Asia with intermediate morphologies between basally branching African species, and more derived Eurasian species.
The Sirban Limestone Formation (SLFm) dolostones cropping out in the Riasi Allochthon (NW Himalaya, Jammu, India) show a range of δ13C (−1.08 to 0.73‰) and δ18O (−11.50 to −7.82‰) values and the mean values of 0.15‰ and −9.12‰ Pee Dee Belemnite (PDB), respectively. The δ13C values indicate that these dolostones were deposited during Neoproterozoic, and the δ18O values also are very close to the average Mesoproterozoic carbonate values obtained from the coeval carbonates. The characteristic δ13C values have the potential to provide an age constraint for the SLFm, and the mean δ18O value is comparable to the ‘best preserved’ δ18O mean value (−7.5 ± 2‰) reported for most of the Meso-Neoproterozoic to Early Cambrian carbonates. δ13C vs. δ18O plot for the SLFm suggests normal marine origin with late-stage cementation. In the present study, stable isotope geochemistry of the SLFm dolostones is attempted. Preliminary data on the major-and-minor elemental composition of SLFm has also been presented. In addition, several petrographic facies identified in the SLFm have also been documented here. Diagenesis characterisation of these facies show dolomitization represents an important phase in the early diagenesis process. The subsequent diagenetic stages range from early seafloor cementation to late-stage tectonic stylolitisation, which have obliterated the original textures to dominant diagenetic textures, also reflected in the δ13C and δ18O values. Similar isotope profiles can be potentially significant for the chemostratigraphic correlation of different sections within the Riasi Allochthon and coeval equivalents regionally and globally.
Hinterland basins are low-lying and often heavily populated areas at the back of orogenic belts which have significant economic and infrastructural importance. The tectonic-stratigraphic and regional characterisation of hinterland basins is fundamental for evaluating their subsurface utilisation and potential geohazards.This study focuses on the origin and development of the Tuscan hinterland basins of the Northern Apennines. These basins have been associated with a compressional regime lasting until the Late Pliocene-Pleistocene during which out-of-sequence thrusts and back-thrusts in the inner portion of the chain accommodated the compressive stress accumulated in the frontal zones. An alternative interpretation considers the evolution of these basins in an extensional regime as an effect of large-scale back-arc processes or gravitational collapse of thickened crust following the Apennine orogeny since the Early Miocene. In this tectonic regime, the basins have been interpreted as graben, half-graben or bowl-shaped basins evolving into graben.Our work aims to determine the tectonic-sedimentary evolution of the Valdera-Volterra Basin through the analysis of ~271.8 km of 2D seismic reflection profiles and wireline logs from two exploration wells. The Valdera-Volterra Basin basin is an NW–SE oriented depocenter ~60 km long ~30 km wide filled with a clastic succession of Miocene-Pleistocene fluvial-lacustrine to marine deposits up to ~2 km thick.The analysis has revealed a polyphased tectonic history of the basin with a Messinian-Zanclean compressional phase deforming the basin-infill as indicated by seismic imaging of synformal geometries and strongly tilted unconformities. Such deformation is tentatively associated with E/NE vergent blind thrusts and SW vergent blind back-thrusts. During the Piacenzian, the activity of normal border faults and the presence in their hanging wall of associated sedimentary wedges thickening towards NE suggest an extensional phase following the earlier Messinian-Zanclean compression. Broad folding of the shallow Piacenzian units in the hangingwall of the normal faults suggests the occurrence of mild positive inversion at the end of the Piacenzian/Lowermost Pleistocene?.This tectonic history has been associated with crustal shortening in the Northern Apennines hinterland, accommodated by thrusting, that occurred discontinuously until the end of the Pliocene/Lowermost Pleistocene?. The formation of the border faults during the Piacenzian has been related to a prolongated phase of tectonic quiescence that led to the collapse of the sedimentary pile and the Pre-Neogene substrate. In this setting, the positive inversion occurred at the end of the Piacenzian/Lowermost Pleistocene? represents the last compressive event related to crustal shortening.
The Makran accretionary wedge developed as a result of subduction of the Arabian Plate beneath the southern margin of Eurasia since the Eocene. Interpretation of 2D seismic profiles calibrated to offshore well data in a study area to the south of Gwadar Bay (SW Pakistan) indicates a major period of accretion from the mid‐Miocene, as evidenced by the occurrence of thick growth strata associated with large‐scale imbricate thrusts. The thrust faults originate from a deep detachment within the mud‐rich Oligocene interval, and well‐developed piggy‐back basin successions occur in thrust hanging walls. In the study area, the thrust structures are sealed by a thick, progradational Pliocene to Recent interval in which the presence of submarine canyons, up to 2.5 km across, indicate that sedimentary transport was from the north.
The Late Paleocene to Middle Eocene Subathu Formation shales in the prospective Himalayan Foreland Basin (HFB) were investigated to assess their source potential and reservoir characteristics. The organic-geochemical analysis of the investigated samples reveals that the total organic carbon (TOC) content ranges from 0.3 to 42.4 wt%, with an average value of 7.5 wt%. The visual kerogen assessment (VKA), the modified van Krevelen diagram and the HI versus Tmax crossplot indicate the prevalence of type III (gas-prone) kerogen. This is supported by the presence of significant amounts of vitrinite and inertinite group macerals, suggesting deposition in proximity to the source (e.g., swamp forest) in nearshore paludal (marshy) environments. The maximum pyrolysis yield temperature (Tmax) values range between 340 degrees C and 607 degrees C, suggesting immature to postmature gas generation stage. The vitrinite reflectance (Ro) values of the basal shale sequence range from 1.16 to 3.6 %, and their high maturity is attributed to their proximity to a major backthrust. The estimated hydrocarbon generation, migration, and retention data suggest a 91%-99% expulsion of hydrocarbons from the Subathu Fm shale. The bulk mineralogical data confirm the dominance of clay minerals (average 54.5%), which decreases up-section, where the younger shales have lesser clays and higher silica content. The kerogen type, richness and level of maturation along with the poor brittleness support a low fracability potential of the basal Subathu shales for tight gas production. A regional comparison is attempted with the Patala Formation in the Potwar Plateau of Pakistan.
New organic–geochemical investigations of the Eocene Cambay Shale (Cambay Basin, India) from five wells and an open-cast lignite mine reveal that the total organic carbon ranges from 0.37 to 10.68 wt. %, with an average of 2.43 wt. %. The pseudo–Van Krevelen diagram, hydrogen index versus the maximum pyrolysis yield temperature (Tmax) crossplot, and the visual kerogen assessment of the Cambay Shale indicate the dominance of type III kerogen, with some well samples showing mixed type III and II kerogen. The vitrinite reflectance values range between 0.46% and 0.7%, with Tmax values ranging from 387°C to 441°C and are consistent with an immature to early oil generation stage. The dominance of vitrinite macerals and high pristane–phytane (Pr/Ph) ratios (>6) of the well samples indicate an oxic to dysoxic depositional environment, whereas the presence of Botryococcus braunii and low Pr/Ph ratios (<1) in the lignite mine samples suggesting a more reducing brackish water environment. The estimation of hydrocarbons generation, expulsion, and retention data suggest a low retention of 10%–12% of generated hydrocarbons within the Cambay Shale. The mineralogical data show an abundance of clay minerals (average 62.9%), implying poor to moderate mineral brittleness index. The kerogen type and maturity level along with the high clay content and poor to moderate brittleness indicate low fracability, thereby restricting the production potential of the Cambay Shale for tight gas or tight oil exploration.
Archibald Geikie played a fundamental, but largely unrecognized, role in the establishment of the Scottish oil shale industry by providing James 'Paraffin' Young with the critical information about the location, thickness and probable geographical extent of organic-rich shales during their field visit in 1858. Young subsequently used the observations to determine where to buy leases for commercial oil shale extraction and production before any competitors emerged. Geikie acquired his critical knowledge of the area whilst preparing the first map and memoir of the Edinburgh area published in 1859 and 1861, respectively. In 1866, Young's Paraffin Light and Mineral Oil Company Limited opened the Addiewell works, the largest oil shale works in the world at the time. By the late 1860s, there were over 120 works distilling oil in Scotland, mostly from the shales of the Lothians. Eventually, more than 22 million gallons of crude oil a year were produced in the Midland Valley in an industry that employed c. 40 000 people. Although the Scottish oil shale industry eventually closed in the 1960s, Geikie's legacy lives on through a better understanding of the geology of the Midland Valley and the renewed interest in extracting oil and gas from the shales buried beneath.
Extract Sir Archibald Geikie KCB, OM, FRS (1835–1924) was one of the most eminent geologists of the late nineteenth and early twentieth centuries. Geikie was instrumental in the development of the science of geology during this period and the eminence he attained was acknowledged by the bestowal of many prestigious honours. During his distinguished career Geikie held numerous appointments, including Director-General of the Geological Survey of Great Britain, President of the Geological Society, President of the British Association, Trustee of the British Museum and President of the Royal Society (the only geologist to have ever held the latter honour). He was also an accomplished writer and during his career he published over 200 scientific papers, survey memoirs, books, articles and an autobiography. In addition, he was a masterful lecturer to any level of audience and a talented artist. As the most distinguished and influential geologist of the period, he received many notable honours, including a Knighthood in 1891, Knight Commander of the Bath in 1907 and the Order of Merit in 1913. In retirement Geikie continued to work vigorously as demonstrated by his contribution to the famous Geological Survey Memoir of the North West Highland of Scotland published in 1907 which he edited, his numerous obituaries of fellow geologists, geological contributions to Encyclopaedia Britannica and other publications, as well as work on his geological collections and Royal Society history.
There are around 40 new geothermal power projects commissioned in each of the last few years.Growth of the market is around 5% annually and current installed capacity is about 13,300 MW with about the same in development in 24 countries.These figures are impressive, but they do not bear comparison with any of the fossil fuels.However, few will realise that the global oil industry has a cryptic geothermal power potential that is equal to the entire current output of the geothermal industry.The oil industry is ageing.Many areas still produce copious quantities of oil, but the oil comes with an unwanted by-product, water.The volume of water produced is typically is 10-20 times that of the oil; and the water is hot-in some places very hot (>100°C).In a recent study we showed that the power depleted oil production platforms of the North Sea's North Viking Graben produce sufficient hot water to deliver around 60% of the power requirement for each field.A review of global oil and hence water production has enabled us to calculate that power production alone from waste water from producing oilfields could be at least 15,000 MW.
The Himalayan orogeny has shaped the sedimentary basins of the region, where continuous deformation formed both 'conventional' and 'unconventional' petroleum systems at multiple stratigraphic levels ranging in the age from Precambrian to Neogene. Himalaya is considered to be prospective for hydrocarbon exploration because of its suitable tectono-sedimentary environment, oil/gas shows, and the presence of commercial oil and gas discoveries in broadly similar structural settings in the eastern and western regions. Although detailed surface geological mapping, the acquisition of geological data and the drilling of wells has considerably improved the understanding of the geological and structural setting and the hydrocarbon potential of the NW Himalaya, commercial discoveries have remained largely elusive. In the NW Himalaya the Precambrian-Cambrian sequences that are of primary interest include the Salt Range Formation (Potwar Basin), and also some sequences in the Lesser-and-Sub-Himalaya, such as the Proterozoic Sirban Limestone Formation; in the Kashmir and Bhadarwah-Chamba basins further to the northeast, and in the Garhwal Group and the Krol belt in the southeast. The Palaeozoic sedimentary rocks exposed within the Lesser Himalaya and the Tethyan Himalaya (represented by the Kashmir, Zanskar-Spiti, Kinnaur-Uttarakhand and Kumaon basins) have been subjected to low grade metamorphism, and presently have no significant hydrocarbon generation potential. The Cambrian Khewra and the Permian Tobra formations form hydrocarbon bearing reservoirs in the East Potwar. The Palaeozoic stratigraphy of the Zanskar Tethyan Himalaya in northern India is rather similar to that of the Peshawar Basin in Pakistan. The thick argillaceous successions are the best potential hydrocarbon source rock horizons within the Palaeozoic. The Mesozoic and Early Eocene successions of the Tethyan Himalaya were deposited in the shallow southern margin of the Tethys Ocean. In the western Himalaya, the Tethyan Himalayan succession is exposed in Kashmir, Zanskar, Chamba and Spiti basins. The Mesozoic successions include thick sequences of organic material rich argillaceous sediments. The Triassic and Jurassic strata are generally poorly developed or absent in the eastern Potwar Basin, while they get thicker towards the west Potwar and Kohat basins. The sandstones of Jurassic age are proven reservoirs, and potential source rocks are present. The Mesozoic succession of the Kashmir Basin is represented by the formations of the Triassic age. Some of the shales contain organic matter (OM) and could represent viable hydrocarbon source rocks, while some of the limestones, dolomites and sandstones have sufficient reservoir characteristics. The OM content of the argillaceous sediments within the Mesozoic-Tertiary succession of the Zanskar-Spiti Basin (Ladakh Himalaya) is appropriate for hydrocarbon generation. The Cenozoic foreland basin of the Himalayan orogen was deformed by a southward migrating thrust system during the Late Miocene-Quaternary. The Sub-Himalaya Zone contains a sequence of Cenozoic sedimentary rocks divided into the Subathu and Dharamsala ( = Murree) formations, and Siwalik Group. Hydrocarbon source rocks are present in the Subathu and Dharamsala formations; while the Lower Siwalik, Kasauli and Dagshai formations contain potential sandstone reservoirs. The Eocene Subathu Formation is a key exploration target in the NW Himalaya with both potential hydrocarbon source and reservoir rocks sealed by a thick clay sequence. The coeval shales within the Patala and Nammal formations are considered to be the main source rocks in the Potwar Basin, whereas, the fractured carbonates of Palaeocene and Early Eocene age are the main reservoirs. The Miocene Murree Formation is the youngest oil-producing horizon in the Potwar Basin. Palaeocene Hangu Sandstone and Lockhart Limestone are the main reservoirs in the Kohat Basin. The stratigraphy of Kohat-Potwar Basin extends into Margalla, Kalachitta and Samana Ranges. In these ranges the Jurassic-Eocene strata is exposed, so sub-thrust sheets could have hydrocarbon potential. In the NW Himalaya, the surface gas seeps are characterised by a high nitrogen content, and are either thermogenic or biogenic in origin, while the gases encountered in the wells are typically methane rich (dry) with low nitrogen concentrations, indicating thermogenic origin. There appears to be a strong linear correlation between the relative concentration of methane and nitrogen in the Himalayan fore-deep gas shows. There are numerous references to biogenic gas seeps in the Plio-Pleistocene sediments and lignite fields in the Kashmir Valley, and also in the shallow Plio-Pleistocene sediments in the Peshawar Basin. The evolution and establishment of the key petroleum system elements, the generation, expulsion, migration and accumulation (entrapment) of hydrocarbons at multiple stratigraphic levels in NW Himalaya has been controlled by the regional tectonic events. These events are associated with the source rock burial and maturation history, coupled with hydrocarbon generation, 'peak oil' and subsequent migration occurring concomitantly with the peak activity along the major regional thrusts. The complex and variable structural geometries have allowed a variety of traps beneath sections where source rocks have adequate burial depth, and where traps have not been breached. In NW Himalaya, the key to understand the direct relationship between tectonics and the evolution of petroleum systems are the accurate estimates for the timing of the related tectonics and that of the hydrocarbon generation, accumulation and critical moment. Here, the exploration has been hampered by the structural complexity, difficult terrain, drilling complications and poor seismic data quality. Timing of the trap formation vs. hydrocarbon charge, trap integrity, seal presence and capacity, and reservoir quality are the key geological risks that have to be addressed.