Mesozoic Sandstones Research Articles

Source‐To‐Sink Analysis in the Mesozoic SW Junggar Basin, Central Asia: Evidence From Detrital Garnet and Tourmaline Geochemistry

AbstractSource‐to‐sink systems respond to and therefore potentially record topographic and tectonic changes. North of the Tian Shan Belt, the Sikeshu subbasin of the SW Junggar Basin transitioned from active extension in the Triassic to post‐extensional subsidence in the Jurassic‐Cretaceous. Sediment in the Sikeshu subbasin has been shown to be derived from the Tianshan. However, the details of the source‐to‐sink system remain unclear and discrepancies exist between proxy records. The heavy minerals in the Middle Triassic in the Sikeshu subbasin are dominated by garnets. To investigate the garnet sources and decipher the Mesozoic source‐to‐sink evolution, we conducted petrological and sedimentary analysis and detrital garnet and tourmaline geochemistry. We found that the geochemistry of garnets in the Middle Triassic sandstone is most consistent with that of the skarns in the Yili Block (YB) in Tianshan, while the geochemistry of 55%–84% of garnets in other Mesozoic sandstones is consistent with that of garnets in amphibolites in the YB. The geochemistry of the tourmalines since the Upper Triassic is consistent with that of the meta‐sedimentary rocks in the YB and Central Tianshan Block. The dominance of garnets sourced from skarns in the Middle Triassic probably indicates a near‐source point provenance and the broader range of garnet compositions from the Upper Triassic–Lower Cretaceous suggests multiple sources. We infer that the point source changed to multiple sources, which is consistent with the zircon spectra changing from unimodal to multimodal. This change reflects the expansion of the drainage that accompanies a change from active rifting to a post‐rift stage.

Provenance of mesozoic sandstones in the Saurashtra Basin using heavy minerals geochemistry and geochronology: Implications for paleogeographic reconstruction in Western India

Two contrasting Precambrian sources has been established for the Mesozoic sediments of the Dhrangdhara Group at the western margin of India based on the integration of petrography of sandstone, mineral chemistry of tourmaline and rutile, and U–Pb zircon and U–Th–total Pb monazite dating. The geochemical characteristics of rutile and tourmaline indicate sediment supply from metapelites, granites, pegmatite, quartz vein and tourmalinites. The potential source terrains for these stratigraphic zones are comprehended on the basis of the overlap of probability density of zircon and monazite ages. Zircon trace elements and REE concentrations suggest its derivation from granitoids. U–Pb zircon age data reveals four major populations at 3584–2502 Ma (Archean), 2499–1642 Ma (Paleoproterozoic), 1595–1010 Ma (Mesoproterozoic) and 993–539 Ma (Neoproterozoic). In contrast, U–Th–total Pb monazite age data show major age populations at 900–700 Ma and 500 Ma. The mineral chemistry signatures and zircon-monazite age data indicate predominant sediment derivation from metasedimentary rocks of the Aravalli and Delhi supergroup of rocks, with limited input from Archean gneissic (e.g., Mewar Gneisses and equivalents) and granitic (e.g., Berach Granite and equivalents) rocks. Besides, the predominance of zircon and tourmaline grains with high textural maturity supports significant input from sedimentary and metasedimentary rocks from the Aravalli Delhi Fold Belt (ADFB) and Marwar Supergroup. The detrital zircon and monazite age distributions are consistent with the major Precambrian supercontinent assemblies and corresponding orogenies. The Archean age (2.6–2.5 Ga) components correspond to the Bhilwara Orogeny of the ADFB, 1.8–1.7 Ga and 1.0–0.9 Ga correspond to the tectonothermal events associated with the assembly of Columbia and Rodinia supercontinents, respectively. The Neoproterozoic younger age ∼0.75 and ∼0.65–0.50 Ga corresponds to the breakup of the Rodinia supercontinent and the assembly of the Gondwana supercontinent, respectively. The mineral chemical and geochronological data track major global and local orogenies recorded within the ADFB. Therefore, the sedimentary succession of the Saurashtra Basin preserves the records of paleo-drainage pattern and paleogeography of the northwestern margin of eastern Gondwanaland, which is a repository of the sediments derived from the Aravalli-Delhi fold belt and Pan-African orogenies.

Tracing Oligocene−Miocene source-to-sink systems in the deep Levant Basin: A sandstone provenance study

The Levant Basin in the Eastern Mediterranean contains an ∼3-km-thick, predominantly siliciclastic section of Oligocene−Miocene age, which hosts large hydrocarbon reservoirs (“Tamar Sands Play”). Here, we present a provenance study of Oligocene−Miocene sandstones based on detrital zircon U-Pb-Hf and heavy mineral assemblages. Samples were retrieved from four boreholes across the Levant Basin: Myra-1, Dolphin-1, Leviathan-1, and Karish North-1. Our investigations revealed that the sediments are dominated by Neoproterozoic and older Precambrian zircons with variable Hf isotopic composition, indicating that they were mainly reworked from Paleozoic−Mesozoic sandstones of African-Arabian provenance, with minor derivation from the Neoproterozoic basement of the Arabian-Nubian Shield. Variations in the proportions of pre−900 Ma zircons were encountered in various levels of the siliciclastic section. These zircons were markedly enriched (44%−57%) in the Rupelian and Aquitanian−Burdigalian intervals, accompanied by abundant detrital apatite peloids in the heavy mineral fraction, and relatively sparse (21%−38%) in the Chattian−Aquitanian and Langhian−Tortonian intervals, alongside scarce Mesozoic−Cenozoic zircons. These findings allow us to associate the deep-basin detrital record with two sedimentary transport systems that reached the Levant Basin from both NE Africa and Arabia simultaneously until the late Miocene, when sediment transport from Arabia ceased. While Rupelian and Aquitanian−Burdigalian sediments, including the main section of the “Tamar Sands,” were derived mainly from Arabian sources via the Levant continental margin, Chattian−Aquitanian and Langhian−Tortonian sediments were primarily sourced from NE Africa via the Nile Delta. Detrital contribution from the Eurasian side of the Eastern Mediterranean was not identified, suggesting that sand originating in the Arabia-Eurasia collision belt did not reach the Levant Basin.

Fracture Characterization Explores Potential of Phra Wihan Formation, Thailand

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 22845, “Fracture Characterization and Basement Reservoir Potential of Phra Wihan Formation in Southern Part of Uttaradit Province, Northern Thailand,” by Watcharapong Piewmoh, SPE, PTTEP, and Pitsanupong Kanjanapayont, Chulalongkorn University. The paper has not been peer reviewed. Copyright 2023 International Petroleum Technology Conference. Reproduced by permission. _ The complete paper describes the characterization of fractures in the Mesozoic sandstones of the Phra Wihan Formation in northern Thailand. Fracture characterization of outcrop analogs is important to determine the potential of subsurface reservoirs. The methodology used field study and petrography analysis to determine the relationship of fractures and other structures such as bedding planes and fold geometry. In addition, microstructure analysis can assist in the evaluation of a reservoir’s potential. Introduction Basement reservoir sandstones are one of the main targets in a mature onshore oil field in Thailand. But most basement reservoirs of the onshore Tertiary basin are pre-Tertiary and are associated with low quality. Prediction of reservoir quality in low-porosity and -permeability conditions requires an understanding of fractures in the subsurface. Outcrop analogs are key in characterizing fractured reservoirs. Geological Setting The tectonic evolution of Thailand is detailed in the complete paper. The country’s primary geological provinces are subdivided into the following five components, from west to east: - Sibumasu terrane - Inthanon zone - Sukhothai terrane - Nan and Sra Keao sutures - Indochina terrane The Sibumasu and Indochina terranes are major continental masses that collided during the Devonian-Triassic. Two subparallel suture zones exist along the convergence between the Sibumasu and Indochina terranes; one is an accretionary complex defined by the Inthanon zone. Another is a closed back-arc basin defined by the Nan and Sra Keao sutures. The Sukhothai terrane is an island-arc system formed along the margin of the Indochina terrane.

Oil and gas prediction basing on seismic inversion of elastic properties in Chaoshan depression, south China sea

The marine Mesozoic is widely distributed in the northeastern waters of the South China Sea and is an important field for oil-gas exploration in the South China Sea. The Chaoshan Depression is the largest residual depression in this sea. At a previous well, LF35-1-1, no oil and gas have been discovered with then pre-drilling prediction techniques. Post-drill analysis shows that the physical properties of the Mesozoic reservoir are not favorable there. So, in accurate prediction of the oil-gas reservoirs is necessary. Since the drilling at the LF35-1-1, extensive surveys and studies have been carried out which shows a number of favorable trapping structures. In the middle low bulge of the Chaoshan Depression, the DS-A structures found with potential reservoirs, complete trap structures, and dual source hydrocarbon supply on both sides, making it the most favorable zone for oil-gas accumulation. We apply the state of art prediction techniques for it using pre-stack seismic raw gather. The sensitivity analysis results of reservoir physical properties indicate that the difference in P- wave velocity between sand and mudstone is 500 m/s, the difference in density is 0.02 g/cm3, and the Poisson’s ratio ranges between 0.11 and 0.33. The Mesozoic sandstone reservoirs in the Chaoshan Depression have characteristics of high velocity and low Poisson’s ratio, and the P-wave velocity, density, and Poisson’s ratio are the main sensitive parameters for predicting reservoir and its oil-gas bearing properties. The density inversion, P-wave impedance inversion, and S-wave impedance inversion jointly characterize the “wedge-shaped” sand body in the DS-A structural area, with a maximum thickness of over 400 m and an area of ∼130 km2. The overlap of the sand body contour map and Poisson’s ratio inversion results indicates that the “wedge-shaped” sand body is an oil-gas bearing sand body. It can be concluded that pre-stack elastic parameter inversion is an effective method for reservoir prediction in deep-sea no-well exploration areas. It has the characteristics of high signal-to-noise ratio, strong stability and reliability, and high accuracy, which is conducive to reduce the non-uniqueness and uncertainty of seismic inversion. The inversion results predict that the DS-A structure is an oil-gas bearing structure.

Provenance changes revealed by a multi-proxy approach to sandstone analysis and its implications on palaeogeography: Mesozoic Kutch Basin, India

Sedimentary rocks preserve the geological history of a basin and play a key role in constraining the palaeogeography. The Mesozoic Kutch Basin (India) comprises a number of sub-basins representing a pericratonic rift formed during the break-up of Gondwanaland. It preserves sediment deposited during the rifting and drifting of the Indian subcontinent. The current study identifies evidence of provenance changes recorded in Mesozoic sandstone units using a multi-proxy approach of quantitative modal analysis, quantitative heavy-mineral analysis and garnet chemistry. The Mesozoic sedimentary successions in the sub-basins are classified as the Kutch Mainland Group (KMG), the Pachchham Island Group (PIG) and the Eastern Kutch Group (EKG). Although the sub-basins are thought to share sediment from common source areas and the sandstone units are highly mature quartz arenites, the heavy-mineral assemblages (especially the content of zircon, tourmaline, rutile, apatite and staurolite) indicate previously unreported variation in the sediment source for the PIG when compared to the KMG and EKG. Moreover, an increase in the content of staurolite and kyanite in combination with rising trends of the ratios of staurolite–kyanite and zircon–tourmaline–rutile over garnet (St + Ky/Grt and ZTR/Grt) for the Callovian and younger strata is observed in the KMG and EKG. The above indicates a change in source from the older to the younger strata in each of the two sub-basins. The absence of their coeval strata in the PIG gives credence to the previously postulated rise of a subsurface basement high, the Median High in this basin. However, the timing of the rise remained so far unspecified, mentioned as “later in Jurassic” (Biswas, 2016b). The observations made in the current study constrain the rise of the Median High in the Kutch Basin to the Callovian time. The similarities in trends of the ratio of heavy minerals and garnet chemistry as well as variations in igneous garnet suggest recycling within the Kutch Basin from the Callovian to Oxfordian–Kimmeridgian strata in the EKG to the Kimmeridgian to Albian strata in the KMG.Besides revealing previously unknown details in the evolutionary and palaeogeographic history of the different sub-basins constituting the Kutch Basin, this multi-proxy study demonstrates the high potential of using recently developed techniques in provenance analysis i.e., the semi-automated heavy-mineral analysis by Raman spectroscopy and the state-of-the-art machine-learning aided garnet discrimination scheme. This study also provides a globally applicable workflow for other sedimentary basins, especially rift basins characterised by overall highly mature quartz arenites.

Geochemistry and provenance of Mesozoic sandstones in Khon Kaen Geopark: Implication for tectonics of the western Khorat Plateau of Thailand.

Khon Kaen Geopark, representing an area of dinosaur fossil diversity, was selected for investigations to reveal the origin and tectonic setting of the Khorat Group. The area occupied by Mesozoic sedimentary rocks of four formal formations of the Khorat Group, namely the Phra Wihan Formation (PWF), Sao Khua Formation (SKF), Phu Phan Formation (PPF), and Khok Kruat Formation (KKF). A field investigation and macroscopic observations suggested that the immature sedimentary rocks of the study area are mainly clast-supported, pebbly sandstone and siltstone with few calcretes. The 50 rock samples that were selected for petrographical and geochemical investigations revealed that the sandstones of the PWF and PPF are quartz arenite and sublitharenite, with some subarkose, whereas those of the SKF are mainly subarkose and sublitharenite. In addition, the KKF dominantly presents sublitharenite with pebbles and calcretes. Mesozoic sandstones contain quartz, feldspars, various types of rock fragments, and accessory minerals (biotite, muscovite, zircon, and tourmaline), with siliceous, ferrous, and calcareous cement. Petrographic (Q-F-L) and geochemical (major and trace element) data suggested that the sources of sediments are mostly quartzose sedimentary rocks and some felsic-intermediate igneous rocks. Chondrite-normalized rare earth element patterns indicated that the origins of the studied sandstones are quartzose sedimentary rocks deposited in a passive continental margin or an upper continental crust. Geochemical traits of the sedimentary successions demonstrated that the provenance of the Khorat Basin prior to reworking by fluvial processes was situated in the passive continental margin or recycled orogen of the paleo-volcanic arc during the Mesozoic period.

Delineation of Paleochannel and Groundwater Resources in the Khari River Basin, Kachchh using Transient Electromagnetics

Abstract The paleochannels are riverine geomorphic features, which are either buried or shifted due to tectonic, climate, and anthropogenic activities. In general, these channels serve as potential groundwater repositories, and their identification can help in developing potable groundwater sources. Here, the results of transient electromagnetic (TEM) study carried out near and around the Khari river basin of the tectonically active Kachchh intraplate region, western India are presented. The TEM investigations at 22 sites along three traverses have been carried out in the river basin that cut the present-day river channel and its presumed paleochannel. The geoelectric sections of the three profiles decipher information down to 300-350m and suggest a multilayer aquifer system. The sub-surface model infers a deeper confined aquifer at variable depths from 100-150m associated with the river as well as its paleochannel. The paleochannel aquifer is observed to be buried under 15-20m thick unconsolidated sediments that overlie a Mesozoic sandstone layer of the Bhuj Formation. The resistivity sections across the paleochannel suggest a relatively fresh aquifer layer with higher storage capacity. A vertical bedrock offset of 100-120m and the discontinuity of lithostratigraphic layers observed from the study suggest the dominant tectonic control in the formation of the paleochannel that correlated with the location of the reactivated splay of the Katrol Hill Fault.

Origin of Mesozoic Biodegraded Crude Oils from the Eastern Chepaizi Uplift (Junggar Basin) Constrained by the Biomarker Recovery Method

The Mesozoic (Jurassic and Cretaceous) sandstone reservoirs in the eastern Chepaizi Uplift of the Junggar Basin (NW China) have become hot targets in recent years for their substantial amounts of oils discovered. However, the oil origin has been a controversial issue due to biodegradation. In this study, hierarchical cluster analysis and principal component analysis show that the Mesozoic crude oils can be divided into three oil families (A1, A2, and A3). Meanwhile, the biodegradation level of the three oil families (PM 6 to 9+) was evaluated based on the PM scale and the parameter-stripping method of strongly resistant parameters. Allowing for this extremely high biodegradation case, this study adopted a biomarker recovery method to recover the original appearances of the three oil families. Here, eight parameters related to hopane (H), tricyclic terpane (TT), and C24-tetracyclic terpane (C24 Tet) were recovered, the dispersion of eight parameter sets is significantly reduced, and the geochemical characteristics are more obvious, especially for TT. Thus, this reliability and robustness, as well as the similarity between the source rock and the biodegraded crude oils, encourage us to perform oil–source correlation. The oil–source correlation revealed that family A1 was derived from the Permian source rocks in the Shawan Sag, family A2 was mainly derived from the Permian source rocks in the Shawan Sag and mixed with a small amount of oils generated by the Jurassic source rocks in the Sikeshu Sag and the Carboniferous source rocks in the Chepaizi Uplift, and family A3 mainly originated from the Permian source rocks in the Shawan Sag mixed with a small amount of oil produced by the Carboniferous source rocks in the Chepaizi Uplift. This conclusion is also further supported by effective biomarker parameters and a stable carbon isotope (δ13C), discriminant analysis, hydrocarbon migration, and restored paleogeomorphology. The parameter recovery is evidenced as one of the most useful methods and showed higher resolution than the conventional oil–source correlation to identify the origins of biodegraded oils.

Geoeducational assessments in Khon Kaen National Geopark, Thailand: implication for geoconservation and geotourism development

Khon Kaen Geopark (KKGp), located on the Mesozoic sandstone syncline of the Khorat Plateau, northeastern Thailand, is distinguished by spatially small-scale (100–10,000 m2) forms of geodiversity (rocks, fossils, structures, landforms, landscapes, and minerals). Field investigations and classification suggest that paleontological sites present the first dinosaur species in Thailand and confirm the existence of five dinosaur species: Phuwiangosaurus sirindhornae, Kinnareemimus khonkaenensis, Siamotyrannus isanensis, Siamosaurus suteethorni, and Phuwiangvenator yaemniyomi. The geomorphological sites feature representative sandstone landforms, including waterfalls, cliffs, caverns, honeycombs, pedestal rocks, and rugged surfaces with irregular features. In addition, the mineralogical site has a Uranium Field (Cu–U-related ore deposit). This work proposes four geoeducation models: a geodiversity one-day trip, a geomorphological study trail, a geoethical study site, and the Phu Wiang Dinosaur Museum for geoconservation development for school and university students. According to the geoeducation assessment, KKGp has considerable educational value based on the Accessibility, Safety, Invulnerability, Observation condition, and Didactic (ASIOD) framework for geology and geography. Our findings suggest ways to broadly transform and enhance the geoeducation concept through a storytelling narrative of the geopark.

Quest for the Australasian impact crater: Failings of the candidate location at the Bolaven Plateau, Southern Laos

AbstractThe quest for the parent impact structure for Australasian tektites (AAT) has remained without solution for almost a century. The present paper doubts the plausibility of the recently proposed location of the impact site at the Bolaven volcanic field in Southern Laos by showing problems with most of the presented lines of evidence. The geochemical incompatibility of the AAT composition with a mixture of weathered basalts and Mesozoic sandstones that were proposed as source materials of AAT is demonstrated by a two‐component mixing calculation for major element oxides and the Nd‐Sr isotopic system. Deficiency of the basaltic component as a source of Ni, Co, Cr, and 10Be in AAT and inconsistency with trends observed for O and Pb isotopes are shown. The size of the putative crater, conclusiveness of a gravity anomaly identification, signs of complete crater burial by postimpact lava flows, and identification of proximal ejecta blanket are doubted. Remarks on the shortcomings of the current consensus location of an impact site for AAT in Indochina are presented.

Correction to: Estimation of Brittleness Indexes from Petrographic Characteristics of Different Sandstone Types (Cenozoic and Mesozoic Sandstones), Markazi Province, Iran

Correction to: Estimation of Brittleness Indexes from Petrographic Characteristics of Different Sandstone Types (Cenozoic and Mesozoic Sandstones), Markazi Province, Iran

Provenance of Mesozoic sandstones from the northwestern Gulf of Suez, Egypt: new evidence from petrography and whole-rock geochemistry

New investigations of petrographic and geochemical characteristics of Mesozoic sandstones from the northwestern Gulf of Suez in Egypt have been undertaken, documenting dominance of quartzose sandstones containing on average ~ 5% of mostly sedimentary and subordinately metamorphic lithic fragments (siltstone, sandy siltstone, and, more rarely slate, metasiltstone, limestone, dolostone, quartz-muscovite schist, and gneiss). These sandstones are depleted in many chemical elements and display low Al2O3/SiO2 and K2O/Na2O ratios. Mineralogical and geochemical parameters point at extensive recycling from older (i.e., Paleozoic) siliciclastic strata. Relatively constant composition throughout the Mesozoic contrasts with successive palaeogeographic changes associated to the major events of rifting and dispersal, which may be explained by the widespread distribution of Paleozoic clastic wedges all across northern Gondwana.

Estimation of Brittleness Indexes from Petrographic Characteristics of Different Sandstone Types (Cenozoic and Mesozoic Sandstones), Markazi Province, Iran

Estimation of Brittleness Indexes from Petrographic Characteristics of Different Sandstone Types (Cenozoic and Mesozoic Sandstones), Markazi Province, Iran

Tracking sources and paleotectonic settings of Mesozoic sandstones in interlinked rift basins of western India: An integrated approach using petrography and heavy mineral chemistry

Based on integration of field, petrographic and heavy mineral chemical data, this study highlights the source and tectonic setting of the Mesozoic sandstones of Kutch, Saurashtra, Narmada and Cambay basins at the western margin of India, formed by the progressive splitting of the eastern Gondwanaland. The Kutch Basin is dominated by arkosic sandstone, whereas Saurashtra, Narmada and Cambay basins show the predominance of sub-arkose and sub-litharenite. The modal analyses of framework grains in Kutch sandstones indicate basement uplift and transitional continent settings. In contrast, the sandstones of Saurashtra, Narmada and Cambay basins bear imprints of recycled orogenic and craton interior belts. The presence of abraded and detrital quartz overgrowth and rounded zircons in most sandstones reveal the recycling of sediments in these basins. Tourmaline and rutile mineral compositions constrain the possible lithology of source rocks. The tourmaline mineral chemistry (Ca-Fetot-Mg plot) suggests the derivation of sediments from various sources, including Li-poor granitoids associated with pegmatites, aplites, Ca-poor metapelites, metapsammites and quartz-tourmaline-rich granitic rocks. The compositions of rutile grains (Cr vs. Nb plot) in sandstones indicate metapelitic sources. The gamut of all mineral chemical data supports the predominance of sediment sources from quartzo-feldspathic rocks with minor inputs from mafic rocks. Based on available paleocurrent data and correlation of source compositions, we infer that the Mesozoic sediments of Kutch, Saurashtra, Narmada and Cambay basins were primarily sourced by various lithologies of the Aravalli Craton. The Narmada Basin possibly received additional sediment input from the Bundelkhand Craton.

Characterisation of potholes formed on bedrock sandstones at Loei Dun, Phetchabun Geopark, Thailand

Abstract Phetchabun National Geopark comprises varied geosites; one of the fluvial bedrock landforms distinguished here is Loei Dun. This shows many potholes in Mesozoic sandstone of the Nam Phong Formation (Khorat Group). A genetic study of the occurrence of the Loei Dun potholes lends it a higher geoheritage value. For the present study we did fieldwork and carried out petrographical and geotechnical analyses so as to classify and characterise the potholes and consider geotourism potentials. Petrographically, the bedrock sandstone is a lithic arenite which consists of 82-96 percent very fine to coarse, well-sorted subangular sand with low sphericity and calcite cementation. Our geotechnical analysis of the bedrock sandstone suggests that pothole occurrence may be linked to low rock strength and slake durability index with high rock absorption and porosity at Loei Dun. Field studies confirmed the impact of other factors such as joints/faults, fluvial conditions and biological weathering. There are five types of pothole, viz., simple ones, potholes with external furrows, compound potholes, breached potholes and lateral ones. The present study adds educational value to the Loei Dun geosite at Phetchabun Geoparks and cultural and economic aspects can be further strengthened through the development of geotourism in the area.

Geothermal Resources and ATES Potential of Mesozoic Reservoirs in the North German Basin

Mesozoic sandstone aquifers in the North German Basin offer significant potential to provide green and sustainable geothermal heat as well as large-scale storage of heat or chill. The determination of geothermal and subsurface heat storage potentials is still afflicted with obstacles due to sparse and partly uncertain subsurface data. Relevant data include the structural and depositional architecture of the underground and the detailed petrophysical properties of the constituting rocks; both are required for a detailed physics-based integrated modeling and a potential assessment of the subsurface. For the present study, we combine recently published basin-wide structural interpretations of depth horizons of the main stratigraphic formations, with temperature data from geological and geostatistical 3D models (i.e., CEBS, GeotIS). Based on available reservoir sandstone facies data, additional well-log-based reservoir lithology identification, and by providing technical boundary conditions, we calculated the geothermal heat in place and the heat storage potential for virtual well doublet systems in Mesozoic reservoirs. This analysis reveals a large potential for both geothermal heating and aquifer thermal energy storage in geologically favorable regions, and in many areas with a high population density or a high heat demand. Given the uncertainties in the input data, the applied methods and the combination of data from different sources are most powerful in identifying promising regions for economically feasible subsurface utilization, and will help decrease exploration risks when combined with detailed geological site analysis beforehand.

Late Mesozoic sandstone volumes recorded in Gulf of Mexico subsurface depocentres: Deciphering long‐term sediment supply trends and contributions by paleo river systems

AbstractQuantitative assessment of terrigenous sediment flux to the deep basin has mainly been limited to the Cenozoic Era, given challenges with reconstruction of more ancient source to sink systems. Subsurface mapping in the northern Gulf of Mexico basin, where there is a robust database of wells and seismic data, allows estimation of sand‐size grain volumes within 12 chronostratigraphically defined Late Mesozoic supersequences. Five subsurface depocentres with thicknesses of >400 m are identified, revealing a history of sediment routing via major fluvial axes (paleo rivers) southward from a mid‐continent drainage divide. The interpreted paleo‐rivers are further confirmed by compilation and synthesis of published and novel detrital zircon provenance data showing combinations of age peak subsets that vary considerably between depocentres. This study quantifies sediment volumes within each depocentre by inverting porosity over defined gross rock volumes derived from subsurface well logs and 2D seismic mapping. Two temporal trends of progressively increasing grain volume can be related to climatic effects on fluvial discharge and sediment delivery to the depocentres: (1) Late Jurassic to Early Cretaceous (Oxfordian to early Aptian) and (2) Late Cretaceous (Late Aptian to Coniacian). The first temporal trend probably reflects the local climate becoming less arid with northward drift of the North American Plate into higher latitudes. The second trend mirrors increasing Cretaceous paleotemperatures and rising global sea levels. This second trend is also marked by increased shelf margin bypass of sand indicated by deep basin drilling. Partitioning of Late Mesozoic grain volume by fluvial axes shows that the Paleo‐Apalachicola and Paleo‐Mississippi rivers, sourced from Appalachian basement terranes, generated the largest and longest terrigenous sediment flux into the Gulf of Mexico basin in the Late Mesozoic. Overall, Late Mesozoic siliciclastic grain volumes are estimated to be an order of magnitude less than those previously documented for the Cenozoic Era.

Dinoflagellate biostratigraphy of Eastern Indonesia stratigraphy: key of petroleum exploration success

Several major discoveries in the eastern part of Indonesia (e.g. Tangguh and Abadi) have increased more petroleum exploration interest in the area. These sizeable discoveries encountered gas in the Jurassic sandstone, which is a key reservoir target in the Northwest Shelf of Australia. The Mesozoic sandstone provenance is located in the Australian Continental Plate or also known as the Sahul Shelf. Thousands of wells were drilled in the Sahul Shelf and the stratigraphy in this area is well understood. The extension of the Mesozoic sandstone towards Indonesian territory, with much less well information, is one of the keys of success for petroleum exploration. Refinement of the stratigraphy of the eastern part of Indonesia is crucial to understand the extension.To refine the stratigraphy of Eastern Indonesia, especially for the Mesozoic interval, dinoflagellates play a significant role. Several types of this marine biota have been used by Australian stratigraphers as markers. In the case where stratigraphic tie to Northwest Shelf Australia discoveries, key wells or standard chronostratigraphy, dinoflagellate understanding is critical.Dinoflagellate markers are used to mark several subdivisions of Plover Sandstone. Norvick (2001) used W. indotata and D. caddaensis Maximum Flooding Surfaces to subdivide the reservoir target into upper, middle and lower Plover Formation. These surfaces are named after dinoflagellates. More markers were identified to mark the source rock and seal in the petroleum system. To have a detail correlation from Indonesia to the NW Shelf, understanding of dinoflagellates is crucial.

Mesozoic building of the Eastern Tianshan and East Junggar (NW China) revealed by low-temperature thermochronology

The Eastern Tianshan and East Junggar orogenic belts are major constituents of the southwestern Central Asian Orogenic Belt. This study applies low-temperature thermochronology to constrain the thermo-tectonic history of these two domains. Apatite fission track (AFT) dating of Paleozoic basement samples from the Eastern Tianshan and East Junggar dominantly yield Cretaceous (∼126–70 Ma) AFT ages, except for two granitic samples from the East Junggar with older ages of ∼239 and ∼157 Ma, respectively. Thermal history modeling reveals that the Eastern Tianshan and southern part of the East Junggar experienced moderate to rapid basement cooling throughout the Cretaceous. We interpret it as a far-field effect of accretion and collision along the south Eurasia margin since the Early Cretaceous. Major faults were reactivated and thus may have played an important role in controlling localized fast uplift and cooling. We also dated seven Mesozoic sandstone samples collected from the eastern margin of the Junggar Basin. The detrital AFT age peaks, together with inverse thermal history modeling of the basement, reveal that the East Junggar underwent late Permian to Early Jurassic cooling episodes. These cooling events are thought to be related to post-orogenic transpression along major faults and distal effect of Qiangtang-Eurasia collision. Combined with already published evidence, our new data suggest that the Eastern Tianshan and East Junggar did not undergo significant exhumation during the Cenozoic.