Simulation of sea surface temperature changes in the Middle Pliocene warm period and comparison with reconstructions

The Middle Pliocene (ca 3.12–2.97 Ma) is a recent warm period in the Earth’s history. In many respects, the warmth of the Middle Pliocene is similar to the probable warm situation of the late 21st century predicted by climate models. Understanding the Middle Pliocene climate is important in predicting the future climate with global warming. Here, we used the latest reconstructions for the Middle Pliocene—Pliocene Research Interpretation and Synoptic Mapping (PRISM) version 3—to simulate the Middle Pliocene ...     

Benthic foraminiferal fauna turnover at 2.1 Ma in the northern South China Sea

Quantitative analysis of benthic foraminifera from ODP Site 1146 in the northern South China Sea (SCS) shows that abundance of Bulimina alazanensis, sometimes up to about 90%, decreased gradually since 3.2 Ma, especially at 2.1 Ma. Abundance of other benthic foraminiferal species, Globobulimina sub-globosa and Cibicidoides wuellerstorfi, increased after 2.1 Ma. Comparison with changes in oxygen and carbon isotopes of planktonic and benthic foraminifera shows that high abundance values of B. alazanensis corresponded with lower values of oxygen isotope, but for carbon isotope, high values of the species were consistent with heavier carbon isotope of benthic foraminifera and lighter carbon isotope of planktonic foraminifera, respectively, and vice versa. Considering factors such as uplift of Bashi Strait, expansion of the North Hemisphere Glaciation, strengthening of East Asian winter mon-soon and variations in oxygen and carbon isotope of foraminifera, changes of B. alazanensis in ODP Site 1146 suggest that the source of deep water masses of the northern South China Sea changed from the warm Pacific deep water with high oxygen content to Pacific Intermediate water with low oxygen content at 2.1 Ma. In addition, the strengthened East Asian winter monsoon resulted in increased pri-mary productivity, high nutrient and suboxic bottom water. Variations in species of B. alazanensis seemed to be unable to tolerate environmental stress induced by deep water masses and productivity changes.     

Astronomically modulated late Pliocene equatorial Pacific climate transition and Northern Hemisphere ice sheet expansion

The equatorial Pacific underwent a significant climate transition during the late Pliocene, which is characterized by cooling of global sea surface temperatures (SSTs) and formation of a marked SST gradient between the eastern and western equatorial Pacific. Moreover, this transition was nearly synchronous with the late Pliocene Northern Hemisphere glaciation. Probing the relationship among solar insolation, low and high latitude processes is the key to unravel the mechanism of this climate transition. A se...     

The bryozoan genus Conopeum (Electridae) in New Zealand,with description of a new species and discussion of the morphological and genetic characters of Conopeum seurati (Canu, 1928)

ABSTRACT

The status of Conopeum Gray, 1848 in New Zealand is clarified, confirming the presence of three living species – one a naturalised alien, one new to science, and a third that is also known in the Pleistocene. Conopeum seurati (Canu, 1928), a Mediterranean-European species, is naturalised at three localities in New Zealand – Opua, Whangarei Harbour and Whanganui Inlet. Conopeum antipodum n. sp., previously confused with C. seurati, is an estuarine species distributed from Kaipara Harbour to Lyttelton Harbour and is also found in Te Whanga Lagoon at Chatham Island (all New Zealand localities). Conopeum oretiensis Uttley, 1951, first described from Foveaux Strait, is known as far north as Kaipara and Manukau Harbours and is known as a Pleistocene fossil from Napier, New Zealand. There is one other solely fossil New Zealand species – Plio-Pleistocene Electra ongleyi Brown, 1952 is transferred to Conopeum. Sequence data from the 18SrDNA locus confirm that Conopeum antipodum n. sp. is resolved within Conopeum and is distinct from C. seurati.

http://www.zoobank.org/urn:lsid:zoobank.org:act:4FED6730-1C70-4420-B1DA-F1D9046221DF http://www.zoobank.org/urn:lsid:zoobank.org.pub:5C130A99-0869-44A2-885C-338005FBCE07     

Global cooling controls on the chemical weathering as evidenced from the Plio-Pleistocene deposits of the North China Plain

Major element concentrations were analyzed on the sediments of a 203.6-m core from the North China Plain near Tianjin. The chemical index of alteration (CIA), Al2O3-(CaO+Na2O)-K2O diagram and elemental ratios, such as Al/K and Ti/Na, were used to reveal information of chemical weathering in the source regions since the late Pliocene. Results show that the fluvial materials in the North China Plain were derived from vast regions, which were in the early Na and Ca removal stage and underwent numerous upper-crustal recycling processes. Proxies of chemical weathering show a decreasing trend, in parallel with the global cooling since the late Pliocene, suggesting a strong role of the global cooing in controlling the continental chemical weathering intensity.     

First discovery of Promimomys （Arvicolidae） in East Asia

Promimomys asiaticus sp. nov., the first known species of the genus in East Asia, is described. The material was collected from the early Pliocene cave deposit in Dajushah Hill, Huainan, Anhui Province. Promimomys was first found in Europe and considered as the ancestor of the family Arvicolidae. The new species from China is distinct from the type species, P. cor, and other known species in its thicker enamel of uniform thickness, simple anterior loop of ml, and blunt, salient angles. It is more primitive than other known species in Europe and North America and also more primitive than Mimomys bilikeensis of early Pliocene of Inner Mongolia. It is thus the earliest and the most primitive arvicolid rodent known. The discovery of Promimomys asiaticus sp. nov. is significant to the study on the origin and the phylogeny of arvicolids, and to the discussion of the intercontinental dispersal events of arvicolids.     

Rapid denudation of the Himalayan orogen in the Nyalam area,southern Tibet,since the Pliocene and implications for tectonics–climate coupling

The Himalayan orogen characterized by very high variability in tectonic and climatic processes,and is thus regarded as a natural laboratory for investigating the coupling of tectonics and climate,as well as the influence of this coupling on geomorphological processes.This study uses apatite fission track(AFT)dating of samples from a45-km-long section crossing the Great Himalaya Crystalline Complex(GHC)in the Nyalam area,southern Tibet,to constrain the timing and rate of late Cenozoic denudation.The AFT ages can be divided into two groups:(1)15–6 Ma,to the north of Nyalam town,for which the bestfit line of elevation-age has a gentle slope of 0.05,and for which a denudation rate of 0.27 mm/a is calculated;and(2)3–1 Ma,south of Nyalam town,for which the best-fit line has a steep slope of 0.64,and for which a denudation rate of 1.32 mm/a is calculated.The whole AFT ages has a positive correlation with sample elevation(i.e.,older ages are found at higher elevations),and the geographical location of the point of inflexion of the two fitted lines corresponds closely to the junction of Poqu River near Nyalam town.By integrating the AFT data with thermotectonic modeling,it can be inferred that the GHC has experienced two different periods of denudation:(1)slow denudation during middle to late Miocene(15–6 Ma)is recorded in the northern part of the GHC;and(2)rapid denudation from the Pliocene to the Pleistocene(3–1 Ma)is recorded in the southern part of the GHC.An abrupt change in denudation rate occurred between the two periods,with the Pliocene–Pleistocene denudation rate being five times higher than that during the Miocene.This abrupt change in denudation rate during Pliocene pervaded the Himalayan orogen,and was roughly synchronous with a marked change in global climate at 4–3 Ma,and intensification of the Asian monsoon.Importantly,the later period of rapid denudation in the study region closely coupled to the mean annual precipitation,while there is no clear evidence for large-scale faulting activity and associated uplift during this period.Therefore,climate(precipitation)is inferred to be the main cause of the rapid denudation of the Himalayan orogen since the Pliocene.     

Discovery of a Pliocene stone tool at Yuldan, Hebei Province

The stone tool discovered at Danangou valley of Dongyaozitou village, Yuxian, is the earliest stone tool, the specimen is powerful evidence about the origin of the human culture and the historical age from the ancient ape to the human belng. According to the comprehensive studies about the strata, the age was considered to be of Pliocene (about 3 milllon years) and therefore, the discovery possessed great scientific and theoretical significance.     

Pollen evidence from Baode of the northern Loess Plateau of China and strong East Asian summer monsoons during the Early Pliocene

The red clay eolian sequence on the Chinese Loess Plateau (CLP) is an important archive for paleoclimate change from the late Miocene to Pliocene,and can provide significant information for the controversial problems of East Asian monsoon evolution and its forcing mechanism.In this study,we present a pollen record from Baode,northern CLP.The record shows four stages of paleoecological evolution.From 5.6-4.4 Ma,a forest steppe ecosystem developed under an extremely warm period with high seasonal precipitation.Since 4.4 Ma,a drier episode occurred,which prompted parkland landscapes to develop.During 3.5-3.05 Ma,the environment changed to a rather open steppe ecosystem with a much cooler and drier climate.After 3.05 Ma,the vegetation evolved to forest steppe.Using the percentages of arboreal plants to mirror precipitation,and comparing with other published pollen data from the CLP,we find the existence of S-N directionality of the precipitation change and high percentage of arboreal plants in the entire CLP during the Early Pliocene,which suggest the CLP was characterized by a strong East Asian summer monsoon.The strong summer monsoon corresponds well to the low global ice volume,which may illuminate global climate mechanism for the summer monsoon evolution in the early Pliocene.     

成都盆地新生代大邑砾岩的沉积特征

通过对龙门山前陆盆地大邑砾岩的发育层序、沉积特征及物源的分析，建立其垂向相序，总结出大邑砾岩的沉积具冲积扇相的特点；恢复大邑砾岩发育时期的古地貌，推断其至少由三个冲积扇组成：古岷江扇，古青衣江扇，古玉溪扇。同时，结合测年资料，指出大邑砾岩是上新世一早更新世的整合沉积相，有别于全球其他地区同期的不整合事件。大邑砾岩沉积之后，新构造运动活动强烈。