Journal of Palaeogeography最新文献

The Dabie Orogenic Belt, located in east-central China, is known for the greatest outcrop area of the ultrahigh-pressure metamorphic rocks in the world and is typical for studying deep continental subduction and continent–continent collision. However, since lower-grade metamorphic rock occurrence in the core of the ultrahigh-pressure terrane was reported, it has become a new point of concern. This study reported new results. The so-called lower-grade metamorphic rocks are divided into sedimentary rocks and meta-volcanics. The sedimentary rocks consist mainly of fine-grained turbidites formed under an anoxic deep-water lacustrine basin. Laser Ablation–Inductively Coupled Plasma–Mass Spectrometry U–Pb detrital zircon dating indicates that their maximum deposit age is 119.0 ± 1.1 Ma belonging to the mid-Cretaceous Aptian. U–Pb detrital zircon ages from the sedimentary rocks cluster in three age groups: 1) 2773.8–1550.0 Ma (45.0%); 2) 868.8–622.3 Ma (23.0%); 3) 147.0–100.0 Ma (31.5%). And the provenance and tectonic settings of these sedimentary rocks are discussed by synthesizing U–Pb detrital zircon ages, initial Hf isotope ratios, and trace elements of the zircons. Source rocks of the first group were mainly composed of the Paleoproterozoic basement derived from the reworking of the Paleoarchean–Neoarchean Yangtze continental crust. For the second group, its source rocks consisted of Neoproterozoic volcanics mainly from an island arc system, which derived from the reworking of older continental crust in the northern Yangtze Block. The third group's source rocks were chiefly composed of Cretaceous rift igneous rocks derived from the derivation through melting of middle-aged continental crust in the Dabie Orogenic Belt. The meta-volcanics have weighted mean U–Pb ages from 751.0 ± 16 Ma to 786.3 ± 5.9 Ma, and their protoliths formed under a Middle Neoproterozoic island arc system in the northern Yangtze Block. The meta-volcanics underwent a Triassic subduction of different depths and then an exhumation, but the sedimentary rocks did not. The findings suggest that the ultrahigh-pressure terrane had suffered violent subsidence during the mid-Cretaceous, and a four-stage evolution model of the Dabie Orogenic Belt was established accordingly.

Prof. Zeng–Zhao Feng (also known as Z.Z. Feng or Z–Z. Feng in publications) passed away at 20:50 Hrs (Beijing Time) on 5th January, 2023 in Beijing, China. He was the Initiator of the International Society of Palaeogeography (ISP). He was also the Editor-in-Chief of the Journal of Palaeogeography (JoP) both English and Chinese Editions. An extensive list of his publications is included. Prof. Z.Z. Feng was a geoscientist with many talents. He was a researcher, innovator, initiator, author, editor, educator, mentor, organizer, and above all was a great human being! Even at the age of 97, just two weeks before his passing, he was full of energy and enthusiasm in screening manuscripts for the Journal of Palaeogeography. He left a great void in Journalism. We all will miss him as an iconic sedimentologist!

This paper presents a 3D seismic-based case study from the deep-water Niger Delta Basin to investigate sedimentary–tectonic interaction on growth sequence architecture within the thrust-related intraslope or piggyback basins. Gravitational contraction in the lower continental slope had yielded a series of thrust faults and associated folds in the study area, which formed several piggyback basins. These basins were filled by a suite of growth sequences with varying stratigraphic architecture. Analysis of the 3D seismic data recognized three primary seismic facies types respectively as: convergent, draping and chaotic, which contain seven subtypes. These facies types are combined to form different filling successions for convergent or chaotic growth sequences. The convergent growth sequences mainly occur in the deep section of basin fills during strong gravitational deformation, and always began with convergent-baselapping strata succeeded by convergent-thinning strata, representing pond-to-bypass transition in the ponded-basin accommodation space. The chaotic growth sequences mainly occur in the shallow section of basin fills in response to weak gravitational deformation, and usually began with debris-flow deposits succeeded by channel-levee complexes, reflecting dominant erosion-bypass processes in the slope accommodation space. A dynamic fill-and-spill model considering relationship between episodic sedimentation rate and structural growth rate is proposed to explain the formative mechanisms of growth strata units and associated successions. Interaction between glaciation or deglaciation and sea-level change and gravitational deformation history are suggested to be the factor which resulted in the complex stratal stacking patterns, including progradational or retrogradational stacking patterns within convergent growth sequences, and progradational stacking patterns within chaotic growth sequences.

The present work analyzes the monotypic Taenidium barretti ichnofabric developed in abandoned channels and floodplains to understand its paleoecological significance in highly seasonal fluvial systems. The data come from the Cretaceous paleosols of the Marília Formation (Bauru Basin, SE Brazil), in which the T. barretti ichnofabric and rhizoliths represent the biotic record. Beetle larvae are considered to be the most likely T. barretti tracemakers in these paleosols. The intensity and recurrence of bioturbation suggest that the windows of opportunity for beetle population growth were very short and controlled by the progressive substrate desiccation after flood cessation. The characteristics of the trace fossil assemblage suggest soil colonization by r-strategic organisms triggered by flooding events that provided the resource inputs necessary for their living during rainy seasons. The results also show that in fluvial systems with high discharge variations, the boundaries between a “pre-desiccation suite” and a “desiccation suite” in the Scoyenia ichnofacies can be diffuse due to the short duration of colonization windows and progressive terrestrialization of floodplains and channels. Therefore, the frequency of flooding events, the lowered water table, and the rapidity of substrate desiccation constrained colonization by other burrowers and may be considered as first-order factors controlling the generation of a monotypic T. barretti ichnofabric. Thus, the monotypic Taenidium ichnofabric in the Scoyenia ichnofacies context is an ichnomarker of brief windows for colonization in highly seasonal environments.

Sheltered preservation, in which organisms are trapped within shells of cephalopods, is a well-known phenomenon. This preservational style constitutes an important source of paleontological data. Here, we report the first crinoid preserved inside the early Albian ammonite Cleoniceras besairiei Collignon from Madagascar. This crinoid is assigned to the aspidocrinid phyllocrinid (Apsidocrinus, Phyllocrinidae), and constitutes the first phyllocrinid from the African continent, the second from the southern margin of the Tethys (after New Zealand), and also from the southern hemisphere. This specimen represents the youngest occurrence of a phyllocrinid in the world as well, and constitutes one of the youngest occurrences of cyrtocrinids from shallow sea environments, before predation-induced migration of the stalked crinoids to the deep sea refugia due to the so-called Mesozoic Marine Revolution. This finding highlights that ammonite shells may also be a convenient material for studying echinoderms.

Macroalga Gesinella, a carbonaceous compression, is found in the upper part of Doushantuo Formation (Ediacaran) in the Yangtze Platform of South China. Morphologically, it is composed of a thallus (including an oval or oblong lamina and a short-rod-like stipe) and a holdfast (including a cone-shaped rhizome and many filamentous rhizoids). The cone-shaped rhizome connects with the stipe and the long rhizoids grew on the rhizome, meaning that the rhizome grew downwards and inserted into the sediment, while the rhizoids grew in the gaps between the sediment grains to anchor its body on the seafloor. On the lamina, branching and/or unbranching filaments are regularly distributed, so that the oval or oblong lamina can be interpreted as a sac-like body that has been compressed. The filaments on the lamina extend from the three-dimensionally preserved stipe, suggesting that the short-rod-like stipe may have been flexible to support the sac-like body in the water column. With tissue and organ differentiations, Gesinella can be regarded as a eukaryotic macroalga and a high-level metaphyte. Based on measurement and analysis of 108 specimens, the Ediacaran macroalga Gesinella from South China can be divided into three stages: juvenile stage (<3 mm maximum width) identified with difficulty, adult stage (3–10 mm maximum width) interpreted to have grown upwards for sunlight, and senescent stage (>10 mm maximum width) that grew sideways.

The brackish lagoon in the central part of The Netherlands was closed by a dike in 1932 and gradually changed into a lake. Parts of this lake were reclaimed and the surficial sediments of one of the polders (Noordoostpolder), reclaimed in 1942, has been investigated in detail by mapping of the walls of some 1500 km of drainage ditches approx. 1.4 m deep. It appeared that the sediments consist of an uncommonly large amount of silt, to different degrees mixed with reworked peat that had developed during the Holocene transgression. Some sandy deposits occur locally, at places that are at first sight distributed in a haphazard way. The various sandy patches have different characteristics (grain-size distribution, rounding of the grains, mineral composition). These sands cannot have been introduced from the sea, nor can they have been supplied by the rivers that discharged into the lagoon, so they must have a local origin. It is found that several types of Pleistocene sandy or diamictic deposits below the Holocene peat and lagoonal sediments had an irregular topography and became eroded during the Holocene by wave activity. This resulted in sandy deposits around these Pleistocene highs, which consisted of glacial tills (boulder clays), river dunes (formed by aeolian activity along rivers under dry permafrost conditions) and coversand ridges, formed by aeolian activity in a belt between the ice margin and the more distal loess belt. This finding implies that palaegeographical interpretations of local grain-size anomalies in a specific deposit should not only consider facies changes due to changes in the sediment supply, but should also consider local erosion leading to the exposure of previously deposited material with a divergent composition.

Here we describe two newly discovered dinosaur eggs from the Upper Cretaceous Chishan Formation in the Qianshan Basin, Anhui Province, East China. These dinosaur eggs can be assigned to a new oospecies of Stalicoolithidae, Shixingoolithus qianshanensis, based on the following combined features: the larger size of eggs, the uniform eggshell microstructure in the radial section, the smaller height and the larger density of radial microstructures at the inner surface of the eggshell. Radial sections of S. qianshanensis show closely arranged columnar eggshell units forming relatively uniform and dense microstructure; some secondary eggshell units and numerous sub-circular radial microstructures appear separately in the middle and inner parts of the tangential sections, respectively. The discovery of S. qianshanensis provides new fossil types of Stalicoolithidae and represents the first dinosaur relative record in the Qianshan Basin, which offer accurate paleontological evidence of Late Cretaceous–Early Paleocene stratigraphic classification in the Qianshan Basin, Anhui Province.

The Hongshuizhuang Formation is a Meso-Neoproterozoic high-quality source rock in the North China Craton (NCC), comprising abundant organic matter. The present study focuses on the analysis of the Hongshuizhuang Formation in the Zhoukoudian area of the Jingxi sag, discussing its genesis and mechanisms of organic matter enrichment through geological and geochemical methods. The Hongshuizhuang Formation is divided into three members from bottom to top respectively as the lower, middle and upper member. Trace elements analysis indicate that the Hongshuizhuang Formation developed restricted neritic facies in an extensional environment within a continental island arc under a post-orogenic background. The lower and upper members were deposited in a relatively shallow, strongly retained water mass within a suboxic and saline environment influenced by subhumid climate, while the middle member was deposited in an anoxic deep–water environment with relatively low salinity and weak restrictions. The PAAS-normalized rare earth element distributions of the middle and upper members show an enrichment of LREEs and a depletion of HREEs, and a low mean Y/Ho ratio with a positive Eu anomaly, indicating that the regional deposition has been affected by hydrothermal fluids. The negative δ¹³C and δ¹⁸O values and the positive⁸⁷Sr/⁸⁶Sr values confirm that the deposition of the middle and upper members was accompanied by crustal hydrothermal activities. Accumulation of organic matter and enrichment of Ba_xs and P indicate that productivity is the basis of organic matter enrichment in the Hongshuizhuang Formation, where high-quality source rocks are concentrated in the middle member. In addition, reduced water mass controls the preservation of organic matter. Hydrothermal activity, humid climate, and salinity support a higher primary productivity and the formation of reduced water masses. However, due to limitations in depth, the high-quality source rocks in the Jingxi sag are thinner than the Jibei sag.