BOOK REVIEW Authors Veronica Hunt-Lewis, London, UK Search for more papers by this author David N. Lewis Corresponding author E-mail address: email@example.com Department of Earth Sciences, The Natural History Museum, London, UK Search for more papers by this author No abstract is available for this article. Ancillary Article Information DOI …
BOOK REVIEW Authors Stephen K. Donovan Corresponding author E-mail address: Steve.Donovan@naturalis.nl ORCID:orcid.org/0000-0003-3702-9096 Naturalis Biodiversity Center, Leiden, the Netherlands Search for more papers by this author No abstract is available for this article. Ancillary Article Information DOI 10.1002/gj.2900 View/save citation Format Available Full text: HTML | PDF Copyright © 2017 John …
The Lianglitage Formation (also named Lianglitag Formation) is an important hydrocarbon reservoir in the Tarim Basin; the reef and shoal facies of this formation have previously been extensively investigated. The paleokarst of the formation related to a tectonic unconformity at the top of the Ordovician (Tg5) has, however, not been widely investigated. In this paper, we undertake a comprehensive study of the paleokarst by an integrated analysis of seismic data, well‐logging data, and core data. Several geomorphologic units that formed at the end of the Ordovician period are identified, including a fault‐thrust uplift high, inter‐uplifts sag, uplift platform, and fault‐thrust anticline; these units are controlled by west–east and northwest–southeast striking faults. The thickness of erosion is estimated to be 200 to 700 meters. The paleokarst is characterized by large and small caves, dense vugs, and dissolution fractures. Large caves predominantly developed in exposed areas and on the slopes. Dense vugs and small caves, features that contribute to premium hydrocarbon reservoirs, are generally tens of meters away from the unconformity, whereas dissolution fractures, predominantly filled by mud and silts, are situated in close proximity to the unconformity and faults. Four karst zones can be identified from vertical profiles: weathered crust (1–2 m thick), vertical infiltration zone (tens of meters thick), phreatic zone (tens to hundreds of meters thick), and a bottom zone that is largely unaffected by karstification. The karst of the Lianglitage Formation at the end of the Ordovician was mainly controlled by tectonic movement, paleogeomorphology, lithofacies, faults, and fractures. The karstification process is summarized in a karst model.
The concentration of trace and rare earth elements in 22 crude oil and five oilfield water samples, collected from Triassic Yanchang Formation and Jurassic Yanan Formation reservoirs in the Jiyuan Area of Ordos Basin, N China, was determined using inductively coupled plasma mass spectrometry (ICP‐MS) for the first time. The oil samples were analysed to classify the oils into family and to determine the origin and depositional environment of organic matter that yield the oils using trace elements. The REE chondrite‐normalized distribution patterns of the crude oils show light rare earth element (LREE) enrichment and right‐oblique curves. These patterns could be divided into two distinct types that were consistent with that of the upper continental crust (UCC) and lower continental crust (LCC) characterizing by negative Eu anomalies and positive Eu anomalies, respectively. The REE concentrations in coexisting water samples are less than those in crude oils by a factor of ten. Cluster analysis also classified the oil samples from the Ordos Basin into two main groups. Integrated analysis of Co/Ni, V/Ni and V/ (V + Ni) values suggests that the organic matter have more terrigenous source input and the palaeoenvironment was anoxic and slightly oxic conditions. This study differs from previous studies by using trace element analyses of crude oils to constrain oil‐source rock correlation. The results show that most of the crude oils in north Jiyuan area were derived from Chang 7 mudstones while those from Hongde area may be contributed by Chang 7 oil shales. Copyright © 2017 John Wiley & Sons, Ltd.
Palaeoenvironmental reconstructions of the Wealden (Lower Cretaceous) in southeast England have been previously based mainly on field and fossil data. This study presents new interpretations of multi‐proxy data sets such as sandstone petrography, elemental geochemistry and sideritic ironstones, supplemented by outcrop and clay mineralogical data. The dominance of quartz arenites, kaolinite and thorium and the presence of Zr in the sediments suggest that they were sourced mainly from granitic and/or gneissic rocks. Materials from metamorphic sources are secondary in abundance. The mineral and textural maturity of the sediments coupled with inferred short transport distances suggests reworking from older sources. Palaeoclimatic conditions in the source areas were generally warm and humid in nature, which supported an intensive weathering regime. The nature of the sediments suggests they may have been sourced directly or indirectly from a stable craton. The lithology, facies, sedimentary structures, architecture and gamma ray data confirm the freshwater origin of the sediments. Redox‐sensitive trace elements such as Mo, U, V and Co suggest anoxic conditions in the basin. The results presented in this paper reinforce the importance of integrating multi‐proxy data sets for interpreting the palaeoenvironmental conditions of sedimentary basins: when traditional data sets such as field and fossil data are not readily available or insufficient to enable adequate interpretations, the integration of petrographic, mineralogical and geochemical data sets may prove to be useful in similar palaeoenvironmental studies. Copyright © 2017 John Wiley & Sons, Ltd.
The newly discovered Xingwen porphyry Mo deposit is located in the most southern segment of the Xiaoxing’an Range–Zhangguangcai Range metallogenic belt (XZMB), NE China. The Mo deposit occurs with a granitic complex consisting of monzogranite, porphyritic granite and felsite porphyry. The Zircon U–Pb ages of monzogranite, porphyritic granite and felsite porphyry are 170.3 ± 2.1, 168.5 ± 2.5, and 166.7 ± 1.6 Ma, respectively. The inherited zircons from the monzogranite and porphyritic granite yield U–Pb ages of 239.8 ± 5.8 and 249.4 ± 6.2 Ma, respectively. These ages reveal that the Mo mineralization in the most southern segment of the XZMB took place in the Middle Jurassic, and is consistent with the epoch of the largest Daheishan Mo district in the XZMB. In contrast, Triassic ages of the inherited zircons are consistent with the ages of the Triassic magmatic activities along the E–W trending tectono‐magmatic belt in the northern margin of the North China Craton. The εHf(t) of the monzogranite, porphyritic granite and felsite porphyry change from −17.1 to +6.7 , −16.9 to +2.9, −5.94 to −0.90, respectively. The Hf isotopic compositions indicate that old crustal source, juvenile crustal source or depleted mantle contributed to their origin. When compared with the granite in Daheishan Mo district in XZMB, the εHf(t) probably indicates that the granitic complex in the margin of the Central Asia Orogenic Belt may have more old crustal materials than the granitic complex in the inner region of the Central Asia Orogenic Belt. Copyright © 2017 John Wiley & Sons, Ltd.
We present zircon U–Pb and Hf isotopic and whole‐rock geochemical data for late Paleozoic igneous rocks in the central Great Xing’an Range, northeast China, to constrain the late Paleozoic amalgamation history of the united Xing’an–Erguna and Songnen–Zhangguangcai Range massifs. Based on zircon U–Pb dating, we ascertain three main stages of magmatic events: Late Devonian (381–364 Ma), early Carboniferous (360–341 Ma), and late early Carboniferous–early Permian (328–271 Ma). Late Devonian rhyolites originated from partial melting of Meso‐proterozoic accreted lower crust. The crust‐derived rhyolites and coeval mantle‐derived basalts constitute a bimodal volcanic association in the west. Early Carboniferous igneous rocks include syenogranites, monzogranites, gabbro diorites, and gabbros. The granitoids are derived from partial melting of Meso‐proterozoic accreted lower crust. The gabbros and gabbro diorites show the spatial variation in zircon εHf(t) values (−0.53 to +0.84 in the east and +12.3 to +13.5 in the west), which imply that they were mainly derived from metasomatized mantle wedge and asthenosphere mantle, respectively. These characteristics indicate that northwest‐towards high‐angle subduction of the Paleo‐Asian Ocean plate beneath the united Xing’an–Erguna Massif induced arc magmatism in the east and back‐arc magmatism (similar to back‐arc rift) in the west during the Late Devonian to early Carboniferous. Late early Carboniferous–early Permian sub‐alkaline and alkaline igneous rocks are characterized by multiple sources, such as the depleted mantle, juvenile lower crust, and thickening lower crust. Their temporal variations in geochemical characteristics imply that the central Great Xing’an Range was situated under a transitional setting from syn‐collisional to post‐collisional during the late early Carboniferous to early Permian. Using the combined insight from lithofacies palaeogeography and regional magmatisms, we suggest amalgamation of the united Xing’an–Erguna and Songnen–Zhangguangcai Range massifs occurred during the late early Carboniferous to late Carboniferous. Copyright © 2017 John Wiley & Sons, Ltd.
Sapphirine‐bearing granulite from Usilampatti in the Madurai block of southern India preserves a variety of mineral textures and reactions that help in reconstructing a three‐stage metamorphic evolution. Corroded biotite, sillimanite and quartz inclusions within garnet represent relics from the prograde history. Peak metamorphic conditions were attained with the development of sapphirine + quartz in textural equilibrium (Stage 1). This was followed by nearly isothermal decompression, leading to the formation of sapphirine + cordierite at Stage 2. Subsequent retrograde hydration (Stage 3) is only locally evident. Using the Perple_X software and the model system NCKFMASH, the peak P‐T conditions were estimated from core compositions, and the retrograde evolution was deduced from rim or symplectite compositions of different minerals as computed by isopleths of XMg garnet, XCa garnet, XMg orthopyroxene, XMg sapphirine and XMg biotite. The P‐T conditions for Stage 1 thus obtained, and supported by thermodynamic modelling using the winTWQ programme, is approximately 9 kbar and 940°C. Stage 2 conditions were constrained as 6.7 kbar and 900°C. Dating of zircon and monazite in the sapphirine‐bearing granulite and associated gneisses by the U‐Pb method using LA‐ICP‐MS indicates metamorphic overprint of zircon (lower intercept ages of discordant data arrays) at 546 ± 8 and 547 ± 11 Ma and metamorphic growth of monazite between 542 ± 3 and 551 ± 2 Ma. Upper intercept ages for zircon point to zircon growth at approximately 2514 ± 66 Ma. Although it remains unclear whether the metamorphic age data refer to Stage 1 or Stage 2 or, most likely, a continuum between both, they clearly document a late Ediacaran age for ultra‐high temperature (UHT) metamorphism in the area, which, based on the obtained P‐T path, was most likely the result of crustal thickening followed by uplift and erosion. Thus, it is concluded that the sapphirine‐bearing granulites formed in response to Pan‐African orogeny that led to the collision of the western and eastern Madurai domains, whereas initial zircon growth probably took place during late Neoarchaean arc magmatism that formed much of the western domain. Copyright © 2017 John Wiley & Sons, Ltd.
The Broeggeria assemblage is a peculiar brachiopod association that has been recorded mainly from Tremadocian black shales of Baltoscandia, the Anglo‐Welsh Basin, Nova Scotia, South Urals and Kazakhstan. Here, we report a low diversity brachiopod association dominated by Broggeria omaguaca n. sp. from upper Tremadocian open‐shelf mudstones of northwestern Argentina. The dark‐grey transgressive muddy interval bearing the Broeggeria assemblage starts with an erosive flooding surface marked by a glauconite‐rich bed containing reworked bioclasts, which overlies storm‐dominated shoreface sandstones. Lithologic and taphonomic evidence indicates that the fauna from the mudstones represents a palaeocommunity inhabiting oxygen‐depleted bottoms. Besides Broeggeria omaguaca, which by far is the more abundant linguloid, the assemblage includes the obolids Palaeoglossa elongata (Harrington) and Libecoviella aff. tilcarensis Benedetto and Muñoz, and the punctate orthide Lipanorthis andinus Benedetto. Associated trilobites are abundant and low diversity, the more common being the large asaphid Asaphellus jujuanus Harrington. Coeval strata exposed in the Santa Victoria area contain rare specimens of Broeggeria omaguaca associated with Leptembolon argentinum Benedetto and Muñoz and Palaeoglossa elongata. Comparable dysoxic black shales of Furongian age bearing the olenid trilobite Parabolina (Neoparabolina) frequens have yielded a monospecific association of Lingulella n. sp. The records of Broeggeria at global scale support its late Cambrian origin in the Anglo‐Welsh Basin (Avalonia) and its rapid migration into the Karatau–Naryn terrane (a part of the Kazakhstanian collage). By the early Tremadocian, Broeggeria spread to Belgium and to the neighbouring Megumia terrane, migrating later (mid‐late Tremadocian) to Baltica, Southern Urals, Kazakhstanian terranes, Perunica and the Central Andean Basin. By the late Floian/early Dapingian, Broeggeria colonized palaeoequatorial deep shelves (Spitsbergen). Copyright © 2017 John Wiley & Sons, Ltd.
Shale oil exploration of the Permian Lucaogou Formation (P2l) has greatly advanced in the Jimusar Sag in the Junggar Basin. However, despite the strong exploration prospects of shale oil resources, the potential of shale oil resources in the Junggar Basin has been insufficiently assessed. This study performs systematical evaluation of P2l source rocks in the Jimusar Sag and proposes an improved hydrocarbon generation potential method to assess the hydrocarbon generation and expulsion characteristics and evaluates the shale oil resource potential of the P2l source rocks in the Jimusar Sag. The results show that the P2l source rocks are thick (up to 200 m) and are distributed over a wide area (up to 1200 km2) in the study region. It contains high TOC (2%–5%), characterized by dominantly type I and type II kerogen. The source rocks are in the low mature–mature stage, and possess good conditions for generation of hydrocarbons. The P2l source rocks reached the hydrocarbon expulsion threshold at a thermal maturity of 0.8% vitrinite reflectance. The efficiency of hydrocarbon expulsion of the source rock is 34%. The amounts of hydrocarbons generated and expelled were 65 × 108 t. Based on the above information, the shale oil resources potential is calculated to be 43 × 108 t, indicating very good shale oil resource prospect in the P2l source rocks of the Jimusar Sag. Copyright © 2017 John Wiley & Sons, Ltd.