Holocene drainage systems of the English Fenland: roddons and their environmental significance

The roddons of the English Fenlands are fossilised silt and sand-filled tidal creek systems of mid- to late-Holocene age, incised into contemporaneous clay deposits. However, anthropogenic change (drainage and agriculture) has caused the former channels to become positive topographical features. Three stratigraphically discrete generations of roddon have been discriminated. They all show well-developed dendritic meander patterns, but there is little or no evidence of sand/silt infill during meandering; thus, unlike modern tidal creeks and rivers they typically lack laterally stacked point bar deposits, suggesting rapid infill. Major “trunk” roddons are rich in fine sands and there is little change in grain size from roddon mouth to the upper reaches, suggesting highly effective sand transport mechanisms and uniform conditions of deposition. Tributaries are silt-rich, while minor tributaries also have a significant clay component. During infill, active drainage networks appear to have been choked by sediment, converting mudflat/salt-marsh environments into widespread peat-forming freshwater reed swamps.     

Using X-rays as an irradiation source for direct ESR dating of fossil teeth

In this paper we have tested the potential application of X-rays as an irradiation source in Electron Spin Resonance dating of tooth enamel. A range of modern and fossil samples were used to assess the feasibility of dose estimations using this alternative irradiator. The use of a known laboratory additive dose allows the calculation of an absorption equivalent coefficient between gamma-rays and X-rays. The results show that equivalent doses obtained with gamma-rays on fossil powder enamel was frequently less than the doses obtained on fragments using only X-rays. This agrees with other studies that gamma irradiation can lead to age underestimation problems, and also indicates that X-ray sources could be more suitable for ESR dating. Here, we show that testing penetration attenuation for each individual irradiation source is required to accurately estimate the maximum enamel thickness and produce reliable protocols. We conclude that X-rays are an alternative irradiation source for ESR dating protocols, however, limitations remain in particular with alpha efficiency.     

Potential emissions of CO2 and methane from proved reserves of fossil fuels: An alternative analysis

Scientists have argued that no more than 275 GtC (IPCC, 2013) of the world’s reserves of fossil fuels of 746 GtC can be produced in this century if the world is to restrict anthropogenic climate change to ≤2 °C. This has raised concerns about the risk of these reserves becoming “stranded assets” and creating a dangerous “carbon bubble” with serious impacts on global financial markets, leading in turn to discussions of appropriate investor and consumer actions. However, previous studies have not always clearly distinguished between reserves and resources, nor differentiated reserves held by investor-owned and state-owned companies with the capital, infrastructure, and capacity to develop them in the short term from those held by nation-states that may or may not have such capacity. This paper analyzes the potential emissions of CO₂ and methane from the proved reserves as reported by the world's largest producers of oil, natural gas, and coal. We focus on the seventy companies and eight government-run industries that produced 63% of the world’s fossil fuels from 1750 to 2010 (Heede, 2014), and have the technological and financial capacity to develop these reserves. While any reserve analysis is subject to uncertainty, we demonstrate that production of these reported reserves will result in emissions of 440 GtC of carbon dioxide, or 160% of the remaining 275 GtC carbon budget. Of the 440 GtC total, the 42 investor-owned oil, gas, and coal companies hold reserves with potential emissions of 44 GtC (16% of the remaining carbon budget, hereafter RCB), whereas the 28 state-owned entities possess reserves of 210 GtC (76% of the RCB). This analysis suggests that what may be needed to prevent dangerous anthropogenic interference (DAI) with the climate system differs when one considers the state-owned entities vs. the investor-owned entities. For the former, there is a profound risk involved simply in the prospect of their extracting their proved reserves. For the latter, the risk arises not so much from their relatively small proved reserves, but from their on-going exploration and development of new fossil fuel resources. For preventing DAI overall, effective action must include the state-owned companies, the investor-owned companies, and governments. However, given that the majority of the world's reserves are coal resources owned by governments with little capacity to extract them in the near term, we suggest that the more immediate urgency lies with the private sector, and that investor and consumer pressure should focus on phasing out these companies’ on-going exploration programs.     

湖北新洲阳逻镇硅化木研究

作者研究了我国首次在湖北阳逻地区发现的两种硅化木:一种为芸香科吴茱萸Euadia rutaecarpa(Juss.) Benth.,另一种为松科长苞铁杉Tsuga,lngibraceata Cheng。这些木化石的发现为长江中下游地区古气候、古环境、生物群演变,大别山南麓新生代地层时代的归属等问题研究,提供了新的科学论据。     

中国中生代鸟类研究概述

对最近轰动世界的我国中生代鸟类化石的系统结果表明,中国是目前中生代早期鸟类化石产地和化石发现最多的地区,从晚侏罗世到早白垩世存在两个亚纲的鸟类分子,晰鸟亚纳（Sauriurae)和今鸟亚纲（Ornithurae),鸟类从爬行动物分化出来不久即分为两大支系向前演化,孔子鸟（Confuciusornis)和辽宁鸟（Liaoningornis)的发现证明,始祖鸟（Archaeopteryx)只是鸟类进化的一个旁支,不是最早的鸟类,孔子鸟代表鸟类向飞行进行的主流,辽宁鸟是目前今鸟亚纲最早的代表,鸟类在进化过程中渐变和突变同时并存,鸟类的历史应大大向前推移。     

长江源各拉丹冬地区上三叠统结扎群双壳类组合与古环境

在长江源各拉丹冬地区雀莫错一带上三叠统结扎群采获大量双壳类化石,根据产出层位,建立了Quemocuomegalodon orientus-Neomegalodon boeckhi、Halobia superbescens-Halobia disperseinsecta、Amonotis togtonheensis-Cardium(Tulongocardium)xizangensis3个组合.这一生物组合反映的地质时代为诺利期,依据双壳类化石的外部形态和内部构造特征及围岩岩石化学分析,说明垂向上双壳类生活的结扎群具浅—深—浅的古地理变化特征,为区域上地层对比及生物生存环境提供了基础资料.     

Pyrolytic and spectroscopic studies of Eocene resin from Vastan lignite Mine,Cambay basin,Western India

The molecular structure of an Eocene fossil resin (Vastan, Cambay basin, Western India) has been investigated with complimentary spectroscopic techniques. The FTIR spectrum shows strong aliphatic CH _x (3000–2800 and 1460–1450 cm⁻¹) and CH₃ (1377 cm⁻¹) absorptions and less intense aromatic C=C (1560–1610 cm⁻¹) absorptions. The major products from analytical pyrolysis are cadalene based bicyclic sesquiterpenoids including some bicadinenes and bicadinanes. The polycadinane products confirm the fossil material as an Angiosperm dammar resin, associated with inputs of tropical rain forests supported by past climates.     

ESRfrag: A new suite of open access programs for the efficient handling of Electron Spin Resonance spectra of enamel fragments

Accurate decomposition of Electron Spin Resonance (ESR) spectrum is a crucial task to extract compound signal intensities of enamel fragments at different irradiation time, in particular for dose recovery accuracy. While it can be achieved manually, the task is laborious and repetitive. In this paper, we present a new freely available program “ESRfrag” that allows the alignment, merging, and computation of complex angular ESR spectra. This program is an open access web-based code, designed to specifically alleviate the daunting task of working with large amounts of ESR spectra for enamel fragment dating. ESRfrag provides an increased reliability and precision on the results compared to manual calculation by removing operators bias. The program can be freely access through the Geoarchaeology and Archaeometry Research Group website (https://www.garg.org.au/projects).     

南京泗洪炭兽的发现及六合组、雨花台组的时代

在南京六合发现一保存较好的下颌骨化石,保存有5枚完整的臼齿。经刘冠邦教授鉴定,认为与他1993年在江苏北部泗洪地区发现的泗洪泗洪炭兽(Sihongotherium sihongense Liu et zhang)相似,但臼齿相对稍小,且齿冠磨损严重,故仅确定为泗洪炭兽未定种(Sihongotherium sp.),时代属中中新世;其照片经邱占祥院士鉴定也认为属炭兽类无疑。炭兽类始于欧、亚始新世中期,渐新世扩展到非洲和北美,到中新世灭绝。炭兽类在我国过去仅分别发现于内蒙、山西、云南的始新世至渐新世地层中,贵州也曾发现两枚臼齿,但时代不祥。由于化石较重要,经在六合实地调查,化石应产于六合组。六合组和雨花组是归于上新世或中新世,一直有争论,故泗洪炭兽在南京六合的发现,为六合组和雨花台组应为中新世提供了新的重要化石依据。     

贵州大榕古滑坡复活变形特征及滑动机制分析

通过调查大榕古滑坡典型变形特征,研究了古滑体复活的滑动机制。结果表明:古滑体滑动机制为蠕滑-拉裂和滑移-拉裂。古滑坡在其特定的脆弱地质环境条件下,不仅受降雨因素影响,更与人类工程活动密切相关。