Abstract Sediment provenance studies concern the origin, composition, transportation and deposition of detritus, and are therefore an important part of understanding the links between basinal sedimentation, and hinterland tectonics and unroofing. Such studies can add value at many stages of hydrocarbon exploitation, from identifying regional-scale crustal affinities and sediment-dispersal patterns during the earliest stages of exploration to detailed correlation in producing reservoirs and understanding the impact of mineralogy on reservoir diagenesis. This Special Publication records 20 of the papers given at the conference titled ‘Sediment Provenance Studies in Hydrocarbon Exploration and Production’ organized by the Petroleum Group of the Geological Society of London, and held in London from 5 to 7 December 2011. The observations drawn in this introductory section reflect the volume editors’ experience, presentations at the conference and papers within this volume.

Recent orbital and rover missions to Mars have returned high-resolution images that show complex surface landforms in unprecedented detail. In addition, the spectral data sets from mission instruments reveal the presence of a wide array of mineral species on the surface of Mars. These discoveries are changing the analog science requirements of projects targeting exploration missions to Mars. Mission managers now expect field deployments to include complementary investigations of surface processes, rock types, mineral species, and microbial habitats. Earth-based analog sites are selected according to their potential for integrated geological and biological studies, wherein a central theme is the search for life. Geological field studies on Axel Heiberg Island, in the Canadian Arctic, demonstrate that the Isachsen Formation represents a high-fidelity analog for comparative studies of volcanic terrain on Mars. The two sites of interest are located in structurally complex zones (chaotic terrain) where basaltic lava flows, mafic dikes, and sandstone beds of Early Cretaceous age intersect evaporite outliers at the periphery of the diapirs. At the North Agate Fiord diapir and Junction diapir, remnant blocks of basaltic rock are pervasively altered and contain copper and iron sulfides, as well as the secondary sulfates copiapite, fibroferrite, and jarosite (North Agate Fiord diapir). Alteration zones within poorly consolidated quartzitic sandstone consist of thin layers of goethite, hematite, illite, and jarosite. The sites are morphologically different from Martian patera, but they provide access to volcanic successions and evaporites in areas of permafrost, i.e., conditions that are invoked in conceptual models for hydrothermal systems and groundwater flow on Mars.

This paper quantifies the flexural subsidence expected from loading by a volcanic arc. The resulting mathematical model shows that the arc width should grow with time and that the subsidence beneath the load can be estimated from the observed arc width at the surface. Application of this model to the Halmahera Arc in Indonesia shows an excellent fit to observations if a broken-plate model of flexure is assumed. The model also gives an excellent fit to data from East Java, also in Indonesia, where it is possible to forward model gravity anomalies. In particular, the depth, location, and width of the depocenter-associated gravity low are accurately reproduced, although the model does require a high density for the volcanic arc (2900 kg m −3). This may indicate additional buried loads due, for example, to magmatic underplating. Our main conclusion is that loads generated by the volcanic arc are sufficient to account for much, if not all, of the subsidence in basins within ∼100 km of active volcanoes at subduction plate boundaries, if the plate is broken. The basins will be asymmetrical and, close to the arc, will contain coarse volcaniclastic material, whereas deposits farther away are likely to be volcaniclastic turbidites. The density contrast between arc and underlying crust required to produce the Indonesian arc basins means that they are unlikely to form in young intraoceanic arcs but may be common in older and more mature arcs.

The Indonesian region includes several volcanic island arcs that are highly active at the present day, and also contains a record of Cenozoic volcanic activity owing to subduction of oceanic lithosphere at the margins of SE Asia. As a result of long-term subduction, there is a high regional heat flow, and a weak crust and lithosphere, as identified in other subduction zone backarcs. The stratigraphic record in the Indonesian region reflects a complex tectonic history, including collisions, changing plate boundaries, subduction polarity reversals, elimination of volcanic arcs, and extension. The arcs have not behaved as often portrayed in many arc models. They mark subduction but were not continuously active, and it is possible to have subduction without magmatism. Subduction hinge retreat was accompanied by significant arc volcanism, whereas periods of hinge advance were marked by reduction or cessation of volcanic activity. Growth of the region occurred in an episodic way, by the addition of ophiolites and continental slivers, and as a result of arc magmatism. In Indonesia, relatively small amounts of material were accreted from the downgoing plate during subduction, but there is also little evidence for subduction erosion. During collision the arc region may fail, resulting in thrusting, and the weakest point is the position of the active volcanic arc itself. Volcanic arcs shift position suddenly, and arcs can disappear during collision by overthrusting. Arcs are geologically ephemeral features and may have very short histories in comparison with most well-known older orogenic belts. The stratigraphic record of the basins within arc regions is complex. Because of a weak lithosphere the character of sedimentary basins may be unusual, and basins are commonly very deep and subside rapidly. There is a high sediment flux. The volcanic arc itself influences the stratigraphic record and basin development. The load imposed by the volcanic arc causes flexure and provides accommodation space. The volcanic arc thus can form the basin and supply most of its sediment. Tropical processes influence the mineralogy and apparent maturity of the sediment, especially volcanogenic material. A complex stratigraphy will result from the waxing and waning of volcanic activity.

The stratigraphic record of volcanic arcs provides insights into their eruptive history, the formation of associated basins, and the character of the deep crust beneath them. Indian Ocean lithosphere was subducted continuously beneath Java from ca. 45 Ma, resulting in formation of a volcanic arc, although volcanic activity was not continuous for all of this period. The lower Cenozoic stratigraphic record on land in East Java provides an excellent opportunity to examine the complete eruptive history of a young, well-preserved volcanic arc from initiation to termination. The Southern Mountains Arc in Java was active from the middle Eocene (ca. 45 Ma) to the early Miocene (ca. 20 Ma), and its activity included significant acidic volcanism that was overlooked in previous studies of the area. In particular, quartz sandstones, previously considered to be terrigenous clastic sedimentary rocks derived from continental crust, are now known to be of volcanic origin. These deposits form part of the fill of the Kendeng Basin, a deep flexural basin that formed in the backarc area, north of the arc. Dating of zircons in the arc rocks indicates that the acidic character of the volcanism can be related to contamination of magmas by a fragment of Archean to Cambrian continental crust that lay beneath the arc. Activity in the Southern Mountains Arc ended in the early Miocene (ca. 20 Ma) with a phase of intense eruptions, including the Semilir event, which distributed ash over a wide area. Following the cessation of the early Cenozoic arc volcanism, there followed a period of volcanic quiescence. Subsequently arc volcanism resumed in the late Miocene (ca. 12–10 Ma) in the modern Sunda Arc, the axis of which lies 50 km north of the older arc.