Jingeng Sha

Studies on the Early Cretaceous Longzhaogou and Jixi Groups of eastern Heilongjiang, northeast China, and their bearing on the age of supposedly Jurassic strata in eastern Asia

Abstract The coal-bearing Longzhaogou and Jixi Groups in eastern Heilongjiang, northeast China, consist of alternating marine and non-marine deposits containing abundant marine animal and plant fossils. The Jixi Group also yields members of the Johel Fauna that is widely distributed in northern and eastern China. The two groups have been considered as Jurassic or mainly Jurassic in age for a long time. However, recent studies documented that the ammonites, bivalves, dinoflagellates, angiosperms and sporopollens are all of Early Cretaceous rather than Jurassic age. It has been demonstrated that: (1) the Longzhaogou and Jixi Groups and their equivalents, the Johel Group of China and the Transbaikalian Group of Russia, are of Early Cretaceous age, (2) the Barremian-Albian was also a very important period of coal accumulation in northeastern China and perhaps in all of eastern Asia, (3) there existed a large shallow embayment connecting with the Palaeo-Pacific in eastern Heilongjiang, and it was the climate of the embayment that controlled the origin and development of the animal and plant communities of northeastern China during the Early Cretaceous. Correlation between formations in the Jixi and Longzhaogou Groups has also been revised in this paper.

Triassic-Jurassic climate in continental high-latitude Asia was dominated by obliquity-paced variations (Junggar Basin, Ürümqi, China).

Significance Geological records of paleoclimate provide the only constraints on Solar System orbital solutions extending beyond the ∼50-Ma limit imposed by chaotic diffusion. Examples of such constraints are coupled high and low latitude, Triassic–Jurassic (∼198–202 Ma) sedimentary cyclicity in coal-bearing outcrops from the ∼60° N-paleolatitude Junggar Basin (Western China), and contemporaneous tropical basins. Analysis reveals climate variability dominated by obliquity-scale cyclicity in the Junggar Basin and precession-scale cyclicity in the tropics. Together, these geological records empirically constrain orbital solutions by providing joint g4 − g3 and s4 − s3 secular frequency estimates of the Earth–Mars orbital resonance. These results demonstrate the opportunity for developing a new class of solutions grounded by geological data extending hundreds of millions of years into the geologic past. Empirical constraints on orbital gravitational solutions for the Solar System can be derived from the Earth’s geological record of past climates. Lithologically based paleoclimate data from the thick, coal-bearing, fluvial-lacustrine sequences of the Junggar Basin of Northwestern China (paleolatitude ∼60°) show that climate variability of the warm and glacier-free high latitudes of the latest Triassic–Early Jurassic (∼198–202 Ma) Pangea was strongly paced by obliquity-dominated (∼40 ky) orbital cyclicity, based on an age model using the 405-ky cycle of eccentricity. In contrast, coeval low-latitude continental climate was much more strongly paced by climatic precession, with virtually no hint of obliquity. Although this previously unknown obliquity dominance at high latitude is not necessarily unexpected in a high CO2 world, these data deviate substantially from published orbital solutions in period and amplitude for eccentricity cycles greater than 405 ky, consistent with chaotic diffusion of the Solar System. In contrast, there are indications that the Earth–Mars orbital resonance was in today’s 2-to-1 ratio of eccentricity to inclination. These empirical data underscore the need for temporally comprehensive, highly reliable data, as well as new gravitational solutions fitting those data.

A MODEL FOR ORGANIC FOSSILIZATION OF THE EARLY CRETACEOUS JEHOL LAGERSTÄTTE BASED ON THE TAPHONOMY OF “EPHEMEROPSIS TRISETALIS”

ABSTRACT The taphonomic pathways of “Ephemeropsis trisetalis” nymphs (mayfly larvae) were systematically investigated based on fossils of different preservational types, collected during three high–stratigraphic-resolution (mm to cm) excavations in the Lower Cretaceous Yixian Formation in the Sihetun area of western Liaoning, China. All fossils studied are fully articulated either in three or two dimensions, which indicates that decay was terminated at a stage before the exoskeleton became disarticulated. We conclude that the Jehol organic skeletons represent at least two general types of preservation produced by pyritization and collapse/compression, respectively. The two-dimensional compressions show no evidence for authigenic minerals, but the three-dimensionally preserved fossils are wholly or partially pyritized. Our study also indicates that aluminosilicate clay and pyrite mineralization are closely associated with fossil “Ephemeropsis trisetalis” nymphs, suggesting that both clay and pyrite played important roles in lacustrine fossil preservations, as in some marine fossil Lagerstätten. We propose a general model for organic tissue fossilization in the Jehol Lagerstätte based on study of taphonomy of “Ephemeropsis trisetalis” nymphs.

Rudists of Tibet and the Tarim Basin, China: Significance to Requieniidae Phylogeny

Abstract Rudists are a principal biotic component of Cretaceous carbonates in Tibet and in the Western Tarim Basin. Barremian to Maastrichtian carbonate units are widespread on the northern margin of the Indian Plate and in Tethyan tectonic slices that were welded onto Eurasia in successive stages during the Late Cretaceous and Paleogene. In far northwestern Tibet, Barremian-Cenomanian endemic rudists and cosmopolitan orbitolinid foraminifera occupied isolated carbonate platforms in the eastern Tethys. Rudists, corals, and stromatoporoids composed bioherms up to 10 m thick and several kilometers in lateral extent. A unique endemic requieniid rudist, Rutonia, is compared to morphologically similar but older, less derived genera. Associated specimens in this assemblage are indeterminate requieniid valves, monopleurids, and two genera with three radiolitid species that are re-described and taxonomic positions re-evaluated. In southern Tibet, mainly endemic Campanian-Maastrichtian radiolitid rudists and cosmopolitan larger benthic foraminifera contributed to carbonate shelves on the northern Indian Plate near the Cretaceous equator. In the Western Tarim Basin Cenomanian strata yield Tethyan rudist species. Coiling morphometric analysis using the three-dimensional morphology Raup diagram shows that Requieniidae valves in contact with the substrate are convergent with the basic gastropod shell. More derived strongly coiled, younger requieniids were adapted to encrusting or semi-infaunal habits. Stratigraphic analysis confirms that Requieniidae diversity crises coincided with Cretaceous oceanic anoxic events Two end members of valve geometry each appear to be primitive and derived characters respectively and separate the family Requieniidae into two clades that are here recognized as two new subfamilies. The end members are defined by the coiling geometry, whether the spire is close to the plane of commissure or it is translated along the coiling axis and by myophore structures. The older matheroniform clade has a low spirogyrate LV that is translated slightly from the commissure along the coiling axis; this group is composed of Matheronia (and its subgenus Monnieria), Hypelasma, Lovetchenia, Rutonia, and Kugleria. Genera in the younger clade have a tall trochospiral LV that is translated along the coiling axis and consists of Requienia, Toucasia, Pseudotoucasia, Apricardia, Bayleoidea, and Bayleia. Claditics support these relationships.

JURASSIC OSTREOIDA (BIVALVIA) FROM CHINA (TANGGULA MOUNTAINS, QINGHAI-XIZANG PLATEAU) AND THEIR PALEOBIOGEOGRAPHIC CONTEXT

Abstract The Bathonian–Oxfordian ostreid fauna from the main ridge of the Tanggula Mountains of the Qinghai-Xizang Plateau, China, consists of six taxa: Actinostreon gregareum (J. Sowerby, 1815), Actinostreon sp. A, Liostrea birmanica Reed, 1936, Gryphaea (Bilobissa) bilobata (J. de C. Sowerby, 1835), Nanogyra nana (J. Sowerby, 1822) and Eligmus rollandi Douvillé, 1907. Liostrea birmanica is only known from the eastern Tethys and south Xizang area, Eligmus rollandi is limited to the Tethys, G. (B.) bilobata occurs in northwest Europe and the northern Tethys, whereas A. gregareum and possibly N. nana have a complex global distribution between paleo-latitudes 60° north and south. Actinosteon gregareum first occurs in the Sinemurian of northern Chile, and during the Toarcian it underwent trans-Pacific dispersal to arrive in east Africa. During the Bajocian it dispersed rapidly along the southern and northwestern margins of the Tethys, northwestern Europe, and western Canada (Stikine Terrane), but it disappeared from South America in the Aalenian. It occupied Kachchh, southern Xizang, and the northern and northeastern Tethys as early as the Bathonian but it did not reach the northwestern Pacific until the Late Jurassic. The species declined after the Kimmeridgian, being limited to northern Africa (southern Tunisia) and the northwestern Pacific (Japan) during the Tithonian. By the end of the Jurassic it was extinct. Actinostreon gregareum apparently possessed very high fertility typical of opportunists that rapidly colonize new habitats. As a result of ocean current dispersal, presumably by both planktotrophic larvae and postlarval pseudoplankton, it rapidly spread along continental margins and island chains. Occasionally, either directly or by island hopping, it crossed the vast Tethys and Pacific oceans, colonizing all warm and temperate waters at low and intermediate paleolatitudes. It may also have used the Hispanic Corridor as a means of dispersal between the Tethys and Pacific oceans as early as the Toarcian.

Permian to earliest Cretaceous climatic oscillations in the eastern Asian continental margin (Sikhote-Alin area), as indicated by fossils and isotope data

Palaeozoological, palaeobotanical and geochemical analyses of Lower Permian to the lowermost Cretaceous sediments exposed in the southern Russian Far East (Bureya–Jiamusi–Khanka superterrane and the Sergeevka terrane), and higher latitude areas (northern Russian Far East and Spitsbergen) suggest a direct relationship with global climatic events defined by the data from oxygen-isotopic palaeotemperatures. Several positive carbon-isotopic anomalies discovered within the uppermost Cisuralian, Guadalupian, early Lopingian and Aalenian–Bajocian intervals are possibly connected to strong hydrological intermixing of oceanic waters under the influence of considerable thermal gradients.

Middle Jurassic unionids (non-marine Bivalvia) from the Shiwandashan Basin, southern China, with special emphasis on Cuneopsis Simpson

Articulated non-marine unionid bivalves from red beds of the Middle Jurassic lower member of the Nadang Formation of Banyou, Shiwandashan Basin, Guangxi province, southern China, comprise five morphotypes of Cuneopsis johannisboehmi (Frech). They have been recognised on the basis of a population study by their: (1) transversely elliptical shape, with subparallel and substraight dorsal and ventral margins, (2) elongated cuneiform shape, with a shallow concavity near the posteroventral margin, (3) elongated cuneiform shape, with a sharp posterior end, but without a clear posteroventral concavity, (4) sub-triangular shape, with a sharply pointed posterior and a relatively rounded anterior margin and gently convex ventral margin and (5) suboval shape, with a convex ventral margin. The analysis demonstrates that these unionids are morphologically variable and leads to revision of at least 15 species of unionids, which are merged into Cuneopsis johannisboehmi. In the Shiwandashan Basin, the unionids are preserved in two types of shell assemblage (2D and 3D). Morphological features such as relatively thick shells, medium to large inflation, a large H/L ratio (more than 0.5) and anteriorly placed umbones all indicate a habitat of large rivers for this unionid.

Late permian to miocene bivalve assemblages from Hohxil, Qinghai-Xizang Plateau, China.

Nine fossil bivalve assemblages have been recognized in the Hohxil desert area of western Qinghai, China: Wuchiapingian Netschajewiajiangsuensis assemblage, Smithian — Spathian Bakevellia costata — Leptochondria virgalensis — Entolium microtis assemblage, Carnian Halobia austriaca — Halobia yunnanensis — Halobia convexa assemblage, Norian Halobia yandongensis — Halobia aff. dilatata assemblage, Carnian‐Norian Trigonodus carniolicus — Unionites? rhomboidalis assemblage, Bathonian — Kimmeridgian Radulopecten pamirensis ‐ Protocardia stricklandi assemblage, Late Jurassic Pseudolimea ‐ Opis assemblage, Early Cretaceous Eokoreanaia qinghaiensis assemblage, and Miocene Sphaerium nitidum assemblage. The marine bivalves, except for the cosmopolitan Halobia, are Tethyan and characterised mainly the northern margin of the Tethys. Non‐marine taxa are restricted Asian forms. These assemblages are very significant in studying the biostratigraphy, paleobiogeography and tectonic history of the Qinghai ‐ Xizang Plateau. ...

Historical distribution patterns of trigonioidids (non-marine Cretaceous bivalves) in Asia and their palaeogeographic significance

The non-marine trigonioidid bivalves show five phases of radiation in the Cretaceous of Pal-Asia: pre-Aptian (?Valanginian/Hauterivian–Barremian), Aptian, Albian, Cenomanian and Turonian–Maastrichtian. Their distribution patterns show two distinct palaeo-river systems feeding trigonioidids. Before the Cenomanian, the river system occupied the southwestern–southern–southeastern Pal-Asian continental margin areas. During the Turonian–Maastrichtian, it extended along the line of southcentral China−eastern China−northeastern China−northern China and Mongolia−northwestern China–eastern Fergana Basin of Kyrgyzstan−western Tajikistan Basin of Tajikistan–Tashkent area of Kazakhstan−central Kyzylkum of northern Uzbekistan–Aral Sea area of Kazakhstan. Furthermore, the general trigonioidid distribution pattern demonstrates that Japan was probably attached to part of eastern China and/or Korea during the ?Valanginian/Hauterivian–Cenomanian stages.

Taxonomy and evolution of the Triassic conodont Pseudofurnishius.

Pseudofurnishius is a late Anisian (Pelsonian)—early Carnian (Cordevolian) conodont genus of gondolellid stock, characteristic for the Sephardic Province and restricted to the “Southern Tethys” region of the northern margin of Gondwana. Its most commonly found species, Pseudofurnishius murcianus, appears at the base of the Ladinian (Fassanian). The Ladinian material of Spain reveals its ontogeny characterised by initial lateral protrusions from the carina that may develop first mono-platform and later bi-platform units, finally evolving into elaborated multi-denticulated forms. The late Anisian—early Carnian phylogenesis of Pseudofurnishius priscus → P. shagami → P. murcianus is proposed. At the end of the Ladinian, Pseudofurnishius expanded to the entire “Southern Tethys” shelf and into Cimmerian terranes that drifted away from northern Gondwana, now accreted to Eurasia, such as the Sibumasu terrane (Southwest China—Malayan Peninsula).