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.

Abstract 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.

Abstract The history of the European oil and gas industry reflects local and global political events, economic constraints, and the personal endeavours of individual petroleum geoscientists, as much as it does the development of technologies and the underlying geology of the region. Europe and Europeans played a disproportionately large role in the development of the modern global oil and gas industry. From at least the Iron Age until the 1850s, the use of oil in Europe was limited, and the oil was obtained almost exclusively from surface seeps and mine workings. The use of oil increased in the 1860s with the introduction of new technologies in both production and refining. Shale oil was distilled on a commercial scale in various parts of Europe in the late eighteenth century and throughout the nineteenth century but, in the second half of the nineteenth century, the mineral oils and gas produced primarily from shale and coal could no longer satisfy demand, and oil produced directly from conventional oil fields began to dominate the European market. The first commercial oil wells in Europe were manually dug in Poland in 1853, Romania in 1857, Germany in 1859 and Italy in 1860, before the gradual introduction of mechanical cable drilling rigs started in the early 1860s. In the late nineteenth century, the northern part of the Carpathian Mountains in what is now Poland and Ukraine was one of the most prolific hydrocarbon provinces in the world. The Bóbrka Field in the Carpathian foothills of Poland, discovered in 1853, is still producing and is now the oldest industrial oil field in the world. The 1914–18 and 1939–45 world wars were both major drivers in exploration for and exploitation of Europe’s oil resources and in the development of technologies to produce synthetic fuels from the liquefaction of bituminous coal and the combination of carbon monoxide and hydrogen as the Allied and Axis governments struggled to maintain adequate supplies of fuel for their war efforts. In Britain, the first ‘accidental’ discovery of gas was made in 1875 in the Weald Basin, but it was not until 1919 that Britain’s first oil field was discovered at Hardstoft, in Derbyshire, as a result of a government-funded exploration drilling campaign, triggered by the need to find indigenous supplies of oil during World War I. The period of reconstruction after World War II was also critical for the European oil and gas industry with further successful exploration for oil and gas in the East Midlands of England resulting in Britain’s first ‘oil boom’, and the discovery and development of deep gas fields in the Po Valley in northern Italy fuelling the Italian economy for the next 50 years. Drilling technologies developed during Britain’s first oil boom, together with the extrapolation of the onshore geology of the East Midlands oil fields and of the Dutch gas fields, led to the discovery of the huge oil and gas resources beneath the North Sea in the 1960s and 1970s, which enabled Britain, Norway, Denmark and The Netherlands to be largely self-sufficient in oil and gas from the late 1970s until production began to decline rapidly in the early 2000s. Today, oil and gas production in most European countries is at an historical low. Exploration for new sources of oil and gas in Europe continues, although increasingly hampered by the maturity of many of the conventional oil and gas plays, but European companies and European citizens continue to play a major role in the global oil and gas industry.

Abstract The Tertiary Piedmont Basin was reshaped as the Apennines progressively overrode the Alpine retroforeland. Nine basin-wide unconformities were followed by abrupt accommodation turnarounds or high-accommodation/high sediment supply intervals. Unusual stratigraphic discontinuities require a different perspective to reconcile allostratigraphy and sequence stratigraphy, highlighting a wider range of tectonically driven discontinuities (subaerial/subaqueous/regressive/transgressive), diachronism of accommodation and sediment–fairway turnarounds, unusual routing to deepwater, and relationships between fourth- and fifth-order sequences. This approach allows innovative play concepts and prediction of reservoir heterogeneity. Steep gradients and high sediment fluxes favour the development of coarse-grained deltas dominated by hyperpycnal processes and large-scale instability/sediment failures, often expressed by retrogressive slump scars, owing to over-steepening generated by drowning unconformities related to orogenic collapse or basin inversion. During increasing-accommodation intervals, subaqueous erosion leaves remnants of drowned deltas forming stratigraphic traps sealed by prodelta-slope muds. The sediments removed feed turbidites, generated during transgressive intervals and deposited at the toe of oversteepened slopes. These may eventually back-fill the slump scar system and show a fining-upward stacking-pattern owing to the re-establishment of the equilibrium profile. Another play concept relies on the combination of onlapping non-marine to marginal marine deposits against fault-bounded basement highs, sealed by marine muds deposited during the subsequent drowning.

Abstract Many Neoproterozoic successions contain viable hydrocarbon source rocks, even though they were deposited before most extant life forms evolved. Eukaryotic microalgae, bacteria, chlorophyte micoalgae, marine pelagophyte algae and dinoflagellates may have contributed organic matter. Major global-scale glaciations, which are commonly attributed to a ‘snowball’ or ‘slushball’ Earth scenario, or deposited under a ‘zipper rift’ scenario, are believed to have played an important role in the deposition of hydrocarbon source rocks during the mid- Neoproterozoic (Cryogenian). Phases of Cryogenian deglaciation may have culminated in the deposition of high total organic carbon shales and ‘cap carbonates’ in restricted anoxic basins, which may have been carved by ice sheets themselves or, alternatively, formed as restricted extensional half graben as Rodinia began to fragment. One example of these organically enriched deglacial sediments comprises shales and dolostones deposited following the Sturtian glaciation in the Centralian Superbasin of Australia, an amalgam of basins that extends almost continent-wide across Australia. Data from the Marmot MMDD-1 drill core on the Stuart Shelf in the southern part of the Centralian Superbasin, together with previously published data on organic enrichment in the Amadeus Basin in the central part of the Centralian Superbasin, suggest that the deposition of organically enriched shales was widespread during the Sturtian deglaciation.

Abstract The vast amount of new lithostratigraphic, chemostratigraphic and geochronologic data from the Huqf Supergroup (Sultanate of Oman) has established it as the Cryogenian (850–635 Ma) and Ediacaran (635–542 Ma) reference section for the Neoproterozoic of the Middle East Region. A direct litho- and chemostratigraphic comparison of the Huqf Supergroup of Oman with the supposed time-equivalent succession of the Marwar Supergroup in western Rajasthan (India) reveals remarkable affinities in facies evolution and chemostratigraphic signature through time. Ara Group equivalent strata are also found in the Salt Range Formation of Pakistan, which shows an almost identical repetition of evaporites and carbonates with six to seven basin refreshening–desiccation cycles, comparing well with the A0–A6 Ara Group stratigraphy of the South Oman Salt Basin. These similarities bring out a consistent picture of a cratonic setting for the Marwar Supergroup of West Rajasthan, changing into a more open marine setting towards Pakistan until Oman, suggesting an assembly of Oman–Pakistan and India ‘terrains’ prior to being accreted to the Arabian shield sometime after 650 Ma. From a petroleum exploration perspective, key success factors when pursuing the Late Neoproterozoic plays in the Salt Basins of India, Pakistan and Oman are source rock maturity, charge preservation and seal integrity.

Abstract This volume results from a conference intended to assess the exploration and exploitation primarily of onshore fold–thrust belts. These are commonly perceived as ‘difficult’ places to explore and therefore are often avoided by companies. However, fold–thrust belts host large oil and gas fields and barriers to effective exploration mean that substantial resources may remain. This volume shows how evaluation techniques have developed over time. It is possible in certain circumstances to achieve good 3D seismic data. Structural restoration techniques have moved into the 3D domain and simple thermal constraints can be enhanced by using more sophisticated palaeo-thermal indicators to more accurately model burial and uplift evolution of source and reservoirs. Awareness of the influence of pre-thrust structure and stratigraphy and of hybrid thick and thin-skinned deformation styles is supplementing the simplistic thin-skinned fault-bend and fault propagation models employed in earlier exploration. The ‘learning curve’ in fold–thrust belt exploration has not been steep and further improvement seems likely to be a slow, expensive and iterative process with information from outcrop, well penetration and slowly improving seismic data. Industry and academia need together to develop and continually improve the necessary understanding of subsurface geometries, reservoir and charge evolution and timing.

Abstract The Neoproterozoic Eon is relatively poorly known from a petroleum perspective, despite the existence of producing, proven and potential plays in many parts of the world. In tectonic, climatic and petroleum systems terms, the Neoproterozoic to Early Cambrian period can be divided into three distinct phases: a Tonian to Early Cryogenian phase, prior to about 750 Ma, dominated by the formation, stabilization and initial break-up of the supercontinent of Rodinia; a mid Cryogenian to Early Ediacaran phase ( c . 750–600 Ma) including the major global-scale ‘Sturtian’ and ‘Marinoan’ glaciations and a mid Ediacaran to Early Cambrian ( c . post 600 Ma) phase corresponding with the formation and stabilization of the Gondwana Supercontinent. There is increasing evidence that deposition of many mid to late Neoproterozoic (to Early Palaeozoic) organic-rich units was triggered by strong post-glacial sea level rise on a global scale, following the ‘Snowball Earth’ type glaciations, coupled with basin development and rifting on a more local scale. Fieldwork in North Africa including the Taoudenni Basin in Mauritania, Algeria and Mali; the Anti-Atlas region of Morocco and the Cyrenaica, Kufra and Murzuk basins in Libya has added to the understanding of reservoir, source and seal relationships and confirmed the widespread presence of Precambrian stromatolitic carbonate units of potential reservoir facies. Current research on the chronostratigraphy, distribution and quality of source rocks, controls on reservoir quality and distribution of seals in the Precambrian–Early Cambrian hydrocarbon plays throughout South America, North Africa, the Middle East and the Indian Subcontinent is documented in this Special Publication.

Abstract This review covers global uppermost Neoproterozoic–Cambrian petroleum systems using published information and the results of studies undertaken by the Geological Survey of Western Australia (GSWA) on the Neoproterozoic Officer Basin. Both production and hydrocarbon (HC) shows sourced from, and reservoired in, uppermost Neoproterozoic–Cambrian successions occur worldwide, and these provide ample incentive for continuing exploration for these older petroleum systems. However, the risks of charge volume, timing of generation–migration v. trap formation and preservation of accumulation are significantly higher than in conventional Phanerozoic petroleum systems. Therefore, the location and assessment of preserved HC accumulations in such old petroleum systems presents a significant exploration challenge. Organic-rich metamorphosed Proterozoic successions of SE Greenland, the Ukrainian Krivoy Roy Series, the Canadian Upper Huronian Series and the oil shales of the Russian Onega Basin are known as the world's oldest overmature petroleum source rocks. The oldest live oil has been recovered from the McArthur Basin of Australia ( c . 1.4 Ga; Ga is 10 9 years), followed by the Nonesuch oil of Michigan. Numerous other petroleum shows have been reported from Australia, Canada, China, India, Morocco, Mauritania, Mali, Oman, Pakistan, Venezuela and the USA. These demonstrate that generation and migration of Proterozoic petroleum has occurred worldwide. The Siberian Lena–Tunguska province, the Russian Volga–Ural region and the Middle Eastern south Oman petroleum fields exemplify the productive potential of uppermost Neoproterozoic–Cambrian successions, where petroleum generation, migration and trapping were either late in the geological history (Palaeozoic–Mesozoic, Oman) or where accumulations have been preserved beneath highly effective super-seals (Lena–Tunguska). The total resource potential of the Lena–Tunguska petroleum province is estimated to be 2000 Mbbl (million barrels) oil and 83 Tcf (trillion cubic feet) gas. The equivalent proven and probable reserves derived from Neoproterozoic–Early Cambrian source rocks and trapped in Late Neoproterozoic (Ediacaran), Palaeozoic and Mesozoic reservoirs in Oman are at least 12 bbbl (billion barrels) of oil and an undetermined volume of gas. The recovery of 12 Mcf (million cubic feet) of Precambrian gas from the Ooraminna-1 well in the Amadeus Basin in 1963, together with the occurrence of numerous HC shows within the Australian Centralian Superbasin, triggered the initial exploration for Proterozoic hydrocarbons in Australia. This included exploration in the Neoproterozoic Officer Basin, which is reviewed in this paper as a case study. Minor oil shows and numerous bitumen occurrences have been reported from the 24 petroleum exploration wells drilled in the Officer Basin to date, indicating the existence of a Neoproterozoic petroleum system. However, the potential of the Neoproterozoic petroleum system in the vast underexplored Officer Basin, with its sparse well control, remains unverified, but may be significant, as may that of many other ‘Infracambrian’ basins around the world.

Abstract Despite the existence of proven Neoproterozoic–Early Cambrian (‘Infracambrian’) hydrocarbon plays in many parts of the world, the Neoproterozoic Eon, from 1000 Ma to the base of the Cambrian at 542 Ma, is relatively poorly known from a petroleum perspective. The so-called ‘Peri-Gondwanan Margin’ is one region of the Neoproterozoic world that is exciting particular interest in the search for ‘old’ hydrocarbon plays, mainly due to exploration success in time-equivalent sequences of Oman. The ‘Infracambrian’ succession in North Africa is widely accessible, and is already emerging as a hydrocarbon exploration target with considerable potential and with proven petroleum systems in different areas. The Taoudenni Basin (Mauritania, Mali, Algeria) in western North Africa is an underexplored basin, despite the Abolag-1 well (Texaco 1974) gas discovery. New palynological data have recently provided the first definitive Late Riphean age dates for the stromatolitic limestone reservoir sequence in Abolag-1. The widespread presence of stromatolitic carbonate units of potential reservoir facies in many parts of North Africa has been confirmed by new fieldwork in the Taoudenni Basin, in the Anti-Atlas region of Morocco and in the Al Kufrah Basin of Libya. Similar biostratigraphic age constraints have also been obtained from subsurface sequences of the Cyrenaica Platform bordering the East Sirte Basin of Libya, many of which have been traditionally assigned an ‘unconstrained’ Cambro-Ordovician age on the basis of lithological characteristics. Besides the proven, producing, weathered-granite reservoir in East Sirte Basin, the hydrocarbon potential of Neoproterozoic–Early Cambrian sequences developed in structural troughs bordering the south Cyrenaica Platform is still being evalutated. Neoproterozoic–Early Cambrian organic-rich strata with hydrocarbon source rock potential are widespread along the Peri-Gondwanan Margin. Some of the black shales encountered on the West African Craton may be as old as 1000 Ma and predate the Pan-African orogenic event. The Late Ordovician–Early Silurian systems in North Africa and the Middle East may form a good analogue for post-glacial source rock depositional systems in the Neoproterozoic, where black shale deposition may also have been triggered by post-glacial sea-level rise.

ABSTRACT In the Kutai Basin, regional compression reactivated basement extensional faults, inverting the Paleogene depocenters as anticlines that are often flanked on one side by basement thrusts. Over most of the basin, the overlying Neogene section is detached near the top of an overpressured zone and deformed as a thin-skinned fold-thrust belt. Fieldwork and hydrocarbon explorationonthe northern marginof the Kutai Basin, where the sedimentary section is relatively thin compared with the basin center, has provided data in an imaging window where both structural deformation styles can be observed. We contend that even in the deeper parts of the basin center, basement-involved inversion beneath the overpressure zone has influenced the shallower structures that are present in the Mahakam Delta depocenter. In the Mahakam Delta depo-center, the subsequent response to inversion of the Paleogene rift section was controlled in part by heterogeneity in the shallow section, including structures formed through syndepositional loading, delta progradation, normal faults, and marked facies changes. It is proposed that the structural model derived from study of the northern area is applicable to all of the Kutai Basin, including the basin depocenter, an area where only the thin-skinned deformation can be imaged because of the thickness of the Neogene section.