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	2016 Vol. 5 No. 1
	Published: 2016-03-07



	Biopalaeogeography and palaeoecology Lithofacies palaeogeography and sedimentology

Lithofacies palaeogeography and sedimentology

	1	On palaeogeographic map
		Zeng-Zhao Feng
		The palaeogeographic map is a graphic representation of physical geographical characteristics in geological history periods and human history periods. It is the most important result of palaeogeographic study. The author, as the Editor-in-Chief of Journal of Palaeogeography, Chinese Edition and English Edition, aimed at the problems of the articles submitted to and published in the Journal of Palaeogeography in recent years and the relevant papers and books of others, and integrated with his practice of palaeogeographic study and mapping, wrote this paper. The content mainly includes the data of palaeogeographic mapping, the problems of palaeogeographic mapping method, the "Single factor analysis and multifactor comprehensive mapping method - Methodology of quantitative lithofacies palaeogeography ", i.e., the "4 steps mapping method", the nomenclature of each palaeogeographic unit in palaeogeographic map, the explanation of each palaeogeographic unit in palaeogeographic map, the explanation of significance of palaeogeographic map and palaeogeographic article, the evaluative standards of palaeogeographic map and palaeogeographic article, and the self-evaluation. Criticisms and corrections are welcome.
		2016 Vol. 5 (1): 1-27 [Abstract] ( 668 ) [HTML 1KB] PDF (10315 KB) ( 159 )

	28	Beef and cone-in-cone calcite fibrous cements associated with the end-Permian and end-Triassic mass extinctions: Reassessment of processes of formation
		Stephen Kershaw, Li Guo
		This paper reassesses published interpretation that beef and cone-in-cone (B-CIC) fibrous calcite cements were precipitated contemporaneously just below the sea floor in unconsolidated sediment, in limestones associated with the end-Permian (P/T) and end-Triassic (T/J) mass extinctions. That interpretation introduced the concept of a sub-seafloor carbonate factory associated with ocean acidification by raised carbon dioxide driven by volcanic eruption, coinciding with mass extinction. However, our new fieldwork and petrographic analysis, with literature comparison, reveals several problems with this concept. Two key points based on evidence in the T/J transition of the UK are: (1) that B-CIC calcite deposits form thin scattered layers and lenses at several horizons, not a distinct deposit associated with volcanic activity; and (2) B-CIC calcite is more common in Early Jurassic sediments after the extinction and after the end of the Central Atlantic Magmatic Province volcanism proposed to have supplied the carbon dioxide required. Our samples from Late Triassic, Early Jurassic and Early Cretaceous limestones in southern UK show that B-CIC calcite occurs in both marine and non-marine sediments, therefore ocean processes are not mandatory for its formation. There is no proof that fibrous calcite was formed before lithification, but our Early Jurassic samples do prove fibrous calcite formed after compaction, thus interpretation of crystal growth in unconsolidated sediment is problematic. Furthermore, B-CIC crystals mostly grew both upwards and downwards equally, contradicting the interpretation of the novel carbonate factory that they grew preferentially upwards in soft sediment. Finally, Early Jurassic and Early Cretaceous examples are not associated with mass extinction. Three further key points derived from the literature include: (1) B-CIC calcite is widespread geographically and stratigraphically, not clustered around mass extinctions or the Paleocene-Eocene Thermal Maximum (PETM) event; (2) isotope signatures suggest B-CIC calcite formed under high pressure in burial at 7-120鈩? incompatible with interpretation of formation of B-CIC calcite at the redox boundary below the ocean floor; and (3) B-CIC calcite reported in P/T boundary microbialites in one site in Iran is the only occurrence known despite extensive published studies of similar shallow marine settings, demonstrating its formation is localized to the Iran site. Based on the above evidence, our opinion is that B-CIC calcite is best explained as a later diagenetic feature unrelated to rapid Earth-surface environmental change associated with mass extinctions; thus a novel carbonate factory is highly unlikely.
		2016 Vol. 5 (1): 28-42 [Abstract] ( 691 ) [HTML 1KB] PDF (9658 KB) ( 161 )

	43	A review on palaeogeographic implications and temporal variation in glaucony composition
		Santanu Banerjee*, Udita Bansal, Anup Thorat
		This study presents a review on palaeogeographic implications and temporal variations of glaucony covering both modern and ancient records. Phanerozoic glaucony preferably forms in a shelf depositional setting. Deep marine conditions and low seawater temperature discourage formation of glaucony. Around 75% of glaucony is recorded from the Cretaceous to the Holocene sediments, which are related to the abundance of the most common substrates, faecal pellets and bioclasts. TFe₂O₃ (total), Al₂O₃, K₂O and MgO contents of glaucony vary appreciably through geological time. While TFe₂O₃ content of most Mesozoic and Cenozoic glaucony exceeds 20%, it is always less than 20% in Precambrian varieties. High K₂O, Al₂O₃, MgO and low TFe₂O₃ distinguishes the Precambrian glaucony from its Phanerozoic counterpart. Precambrian glaucony, preferably formed within a K-feldspar substrate, is always rich in potassium irrespective of its degree of evolution, while high K-content in Phanerozoic evolved glaucony indicates significant stratigraphic condensation. K₂O vs. TFe₂O₃ relationship of glaucony exhibits three different evolutionary trends corresponding to three common modes of origin. Depositional conditions may influence the composition of glaucony as slightly reducing conditions favours Fe enrichment, whereas oxidising conditions causes Fe depletion in glaucony.
		2016 Vol. 5 (1): 43-71 [Abstract] ( 1199 ) [HTML 1KB] PDF (2390 KB) ( 177 )

Biopalaeogeography and palaeoecology

	72	Detrital zircon dating and tracing the provenance of dinosaur bone beds from the Late Cretaceous Wangshi Group in Zhucheng, Shandong, East China
		Wei An, Hong-Wei Kuang, Yong-Qing Liu, Nan Peng, Ke-Min Xu, Huan Xu, Peng Zhang, Ke-Bai Wang, Shu-Qing Chen, Yan-Xia Zhang
		The mass burial of dinosaur bone fossils in the Late Cretaceous Wangshi Group in Zhucheng, Shandong Province has been a research focus in recent years. However, the provenance of the dinosaur bone fossils and the accurate depositional age of the bone beds remain ambiguous. Through U?Pb dating of detrital zircons collected from six conglomerate samples from dinosaur bone beds, we found that the youngest single grain age (YSG) of sample 090414-24-D was 77.3 Ma, representing the maximum depositional age of the dinosaur fossil beds and sediments. This also indicates that the Hongtuya Formation was deposited during the Campanian. Dating results revealed an age peak of 120~110 Ma, which corresponds with the peak age of volcanic rocks of the Lower Cretaceous Qingshan Group. The volcanic rocks of the Qingshan Group are mainly exposed in Laiyang, to the north of Zhucheng, although a few also appear to the south and northwest. Through analysis of conglomerate composition and palaeocurrents in the sediments containing the bone beds, we found that the three different data sets of gravel compositions of the conglomerates were mainly composed of volcanic or pyroclastic rocks. Three different data sets of palaeocurrents suggested that the main sediment source of the Wangshi Group dinosaur bone beds was from the north?northwest of the Basin. Only one data set had a provenance south of the basin. This study revealed that the areas of Laiyang and the Yishu Fault Zone were the main provenance areas of both the dinosaur bone fossils and sediments of the Wangshi Group in Zhucheng. The southern margin of the Zhucheng Basin may be a secondary source area. This research provides an important basis for judging the deposition time and sediment source of fossil layers in the Wangshi Group, as well as reconstructing the palaeogeography of the Wangshi Group in the Jiaolai Basin.
		2016 Vol. 5 (1): 72-99 [Abstract] ( 871 ) [HTML 1KB] PDF (5791 KB) ( 173 )

Geochemistry and sedimentary environments

	100	Deep-water carbonate dissolution in the northern South China Sea during Marine Isotope Stage 3
		Na Wang, Bao-Qi Huang*, He Li
		The production, transportation, deposition, and dissolution of carbonate profoundly form part of the global carbon cycle and affect the amount and distribution of dissolved inorganic carbon (DIC) and alkalinity (ALK), which drive atmospheric CO2 changes during glacial/ interglacial cycles. These processes may provide significant clues for better understanding of the mechanisms that control the global climate system. In this study, we calculate and analyze the foraminiferal dissolution index (FDX) and the fragmentation ratios of planktonic foraminifera for the 60–25 ka B.P. time-span, based on samples from Core 17924 and ODP Site 1144 in the northeastern South China Sea (SCS), so as to reconstruct the deep-water carbonate dissolution during Marine Isotope Stage 3 (MIS 3). Our analysis shows that the dissolution of carbonate increases gradually in Core 17924, whereas it remains stable at ODP Site 1144. This difference is caused by the deep-sea carbonate ion concentration ([CO₃^2-]) that affected the dissolution in Core 17924 where the depth of 3440 m is below the saturation horizon. However, the depth of ODP Site 1144 is 2037 m, which is above the lysocline where the water is always saturated with calcium carbonate; the dissolution is therefore less dependent of chemical changes of the seawater. The combined effect of the productivity and the deep-water chemical evolution may decrease deep-water [CO₃^2-] and accelerate carbonate dissolution. The fall of the sea-level increased the input of DIC and ALK to the deep ocean and deepened the carbonate saturation depth, which caused an increase of the deep-water [CO₃^2-]. The elevated [CO₃^2-] partially neutralized the reduced [CO₃^2-] contributed by remineralization of organic matter and slowdown of thermohaline. These consequently are the fundamental reasons for the difference in dissolution rate between these two sites.
		2016 Vol. 5 (1): 100-107 [Abstract] ( 623 ) [HTML 1KB] PDF (1629 KB) ( 174 )

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