Carbonate dissolution and deep-water paleoceanography of the South China Sea since the Middle Pleistocene

Based on the data of oxygen isotope, micropaleontology and paleomagnetism, we set up the detailed chronology of Core 17957-2 from the southern South China Sea and discuss the change of carbonate dissolution over the last 800 ka. Down-core variation of carbonate content records the “Pacific-type” cycle of higher glacial values and lower interglacial values, though the core lies above the modern lysocline. Carbonate dissolution indices indicate that several severe dissolution of CaCO₃happened during the transition from interglacial to glacial stages. Spectral analyses of these indices show that the carbonate dissolution periodicities are mainly made up of 500 ka and 100 ka. Compared with the cycles of carbonate dissolution of the Indian Ocean, the long-term (500-ka) periodicity reflects the characteristic of the deep-water circulation of the oceans.     

Isotopic evidence for dramatic climatic changes in East Africa during the Pleistocene

Rainfall decreased dramatically in the Lake Turkana region 1.8-2.0 Myr ago and in the Olduvai Gorge region 0.5-0.6 Myr ago. This is documented by a major increase in the delta18O values of pedogenic and groundwater carbonates at these times. The data suggest that meteoric water of the earlier, more humid climate was 2-4 per mil lower in 18O content than modern waters of these regions.     

A complete human pelvis from the Middle Pleistocene of Spain.

The Middle Pleistocene site of Sima de los Huesos in Sierra de Atapuerca, Spain, has yielded around 2,500 fossils from at least 33 different hominid individuals. These have been dated at more than 200,000 years ago and have been classified as ancestors of Neanderthals. An almost complete human male pelvis (labelled Pelvis 1) has been found, which we associate with two fragmentary femora. Pelvis 1 is robust and very broad with a very long superior pubic ramus, marked iliac flare, and a long femoral neck. This pattern is probably the primitive condition from which modern humans departed. A modern human newborn would pass through the birth canal of Pelvis 1 and this would be even larger in a female individual. We estimate the body mass of this individual at 95 kg or more. Using the cranial capacities of three specimens from Sima de los Huesos, the encephalization quotients are substantially smaller than in Neanderthals and modern humans.     

早-中奥陶世华南古海洋氧化还原变化及其对奥陶纪生物大辐射的意义

为了进一步探讨奥陶纪生物大辐射期间环境影响和控制因素, 对安徽南部将军岭剖面黑色页岩的有机碳含量(TOC)、总硫含量(TS)和黄铁矿硫同位素(δ³⁴S_py)进行测试分析。TOC与TS表现出正相关性, 说明可能是非硫化环境中的沉积产物。δ³⁴S_py在弗洛期表现出显著的负偏移, 在中奥陶世表现出相对幅度更大的波动。结合前人对全球碳酸盐岩晶格中硫酸盐硫同位素(δ³⁴S_CAS)和δ³⁴S_py数据的分析结果, 显示特马豆克期末期至弗洛期中期黄铁矿埋藏分数下降, 硫同位素分馏效应增大, 说明当时海水发生氧化, 对奥陶纪生物大辐射起到重要的促进作用。弗洛期晚期至达瑞威尔期, 不同地区δ³⁴S_CAS相继出现负偏移,δ³⁴S_py发生大幅振荡, 可能是由于海洋中硫酸根浓度较低以及硫化物再氧化所致。     

Early Pleistocene hominid teeth recovered in Mohui cave in Bubing Basin, Guangxi,South China

Since the 1950s, researchers who examine the issue of human beginnings often turn to Africa where there is a picture of human origins and evolution based on African hominid fossils with ages that are constantly revised to be older and older. However, there are many other unsolved problems about early human origins and evolution that may be solved by looking outside Africa. Over seventy years ago, Asia was described as a dispersal center of the earliest human industry, and a key arena for huma…     

Isotope assessment of Holocene human diets in the southwestern Cape, South Africa

Models of seasonal mobility to exploit seasonally abundant food sources have been proposed for prehistoric hunter-gatherers in many parts of the world. Some such hypotheses involve fundamental and insufficiently tested assumptions about the nature of both hunter-gatherer societies and the archaeological evidence that they leave. The present study is an independent test of such a hypothesis proposed for the southwestern Cape of South Africa. In this strongly ecologically differentiated area there are four distinct ecological zones that would have offered four different sets of resources to prehistoric people. Obvious modern seasonal fluctuations in these resources, plus a considerable amount of archaeological evidence, led to the suggestion that prehistoric hunter-gatherers moved in a regular seasonal cycle across the zones; this would have allowed them to make maximum use of temporarily plentiful plant and animal foods in some areas, while avoiding lean periods in others. However, as reported here, direct measurements of food intake, as reflected in the stable carbon isotope ratios of archaeological human skeletons, reveal that this was not the case. The implications of this study extend beyond the relevance to local archaeology to more general questioning of the ways in which archaeological data should be used to generate hypotheses.     

Enamel carbon isotope evidence of diet and habitat of Gigantopithecus blacki and associated mammalian megafauna in the Early Pleistocene of South China

Enamel stable carbon isotope analyses were conducted on the large fossil ape Gigantopithecus blacki and an associated mammalian megafauna from Longgudong Cave in Jianshi and Juyuandong Cave in Liucheng, South China. The range in δ13C values (-18.8‰ to -14.1‰) indicates that G. blacki and other large mammals fed on solely C3 biomass, and lived in forest habitats, and not open country or savannas. These results are consistent with other faunal and floral analyses for that time. The diet and habitat of G. blacki were significantly different from those of early hominins (Australopithecus and Paranthropus) from South and East Africa. Extinction of G. blacki probably was a result of forest habitat fragmentation and deterioration.     

New evidence for human occupation of the northern Tibetan Plateau, China during the Late Pleistocene

The described stone artifacts are recovered from the 70 m-high terrace (4600 m a.s.l.) at the southeastern shore of the Siling Co on the northern Tibetan Plateau. The terrace was formed during the Interstadial period before the LGM, ca. 40-30 ka B.P. based on paleoenvironmental research. The Paleoliths from the Siling Co provide evidence for early human occupation of the northern Tibetan Plateau. They show technological and typological affinities with the European Middle Paleolithic suggesting that the early human occupation here might relate to migratory waves during the Late Pleistocene that dispersed humans across the Old World.     

黔南地区地下水资源及其开发利用

通过对贵州黔南地区地下水资源的形式,补给埋藏特点,分布规律的分析研究,提出了该地区地下水资源可持续开发利用的途径和形式。     

海洋牧场生物资源养护原理与技术

生物资源养护是现代化海洋牧场建设的最核心内容,是一个复杂的系统工程。目前我国有关海洋牧场生物资源养护的理论基础较弱,制约了我国现代化海洋牧场建设的技术进步。本文将海洋牧场生物资源养护分为资源恢复工程和保护管理工程两部分。资源恢复工程包括增殖放流和自然增殖,强调了增殖放流活动应该有利于海洋牧场生态系统的食物网结构优化,增殖放流前应该进行增殖潜力评估;自然增殖应该注重海洋无脊椎动物幼虫附着变态机理研究与重要经济动物产卵场恢复技术研发。在保护管理工程部分,重点论述了栖息地修复与保护、生物资源调查与监测、生物资源评估与预测、生物资源科学采捕四部分内容。最后,作者提出了我国海洋牧场生物资源养护的建议与对策,包括加强基础理论和关键技术装备研究、协调好生物资源-修复设施-海洋环境三者之间的关系、加强多学科交叉合作、加强政府部门、科研单位和企业之间合作。     

砗磲人工繁育、资源恢复与南海岛礁生态牧场建设

南海珊瑚岛礁是海洋生态系统的重要组成部分,是区域特色海洋和渔业生物资源及其多样性的保障。砗磲是珊瑚岛礁的构成物种,具有优良的造礁、固礁护礁功能,并为其它岛礁生物提供栖息地、繁育和庇护场所;近二十多年来,在人类活动和全球环境变化影响下,砗磲及珊瑚等岛礁生物资源受到比较严重的破坏,其岛礁生态牧场天然参与者和构建者的功能受损明显。我们突破砗磲幼虫虫黄藻植入难点和变态率极低的瓶颈问题,率先在海南成功研发了砗磲规模化人工繁育和中培技术,并进行了放流增殖试验,取得了良好的效果。但目前和今后砗磲及珊瑚等生物资源情况依然严峻,期望今后开展更系统、科学、更大规模的基于砗磲、珊瑚及其它重要礁栖生物的放流增殖与生态牧场构建,全面恢复南海珊瑚岛礁的生态环境和生物资源,推动南海的可持续发展。     

陕西北部地区晚更新世的植被与气候

目的 探究黄土高原中部晚更新世的古气候演化特征,揭示其变化规律.方法 通过对陕西富县剖面的地质调查、密集采样和54个样品的孢粉分析进行综合研究.结果 将孢粉图式划分为Ⅰ、Ⅱ、Ⅲ3个带,分别代表S1、L1和S03个形成时期的孢粉带:Ⅰ带为榛-菊-蒿组合带,以草本植物孢粉占多数,乔木植物花粉出现高峰为特征;Ⅱ带为菊、蒿优势带,以草本植物花粉占优势,乔木植物花粉显著减少为特征;Ⅲ带为松-藜-中华卷柏增长带,以松、藜、中华卷柏显著增加,乔木植物明显增长为特征.结论 S1形成时期植被为疏林草原,气候温暖较湿;L1形成时期植被为干草原,气候冷干;S0形成时期植被为森林草原,气候温凉干旱.     

Early onset and tropical forcing of 100,000-year Pleistocene glacial cycles

Between 1.5 and 0.6 Myr ago, the period of the Earth's glacial cycles changed from 41 kyr, the period of the Earth's obliquity cycles, to 100 kyr, the period of the Earth's orbital eccentricity, which has a much smaller effect on global insolation. The timing of this transition and its causes pose one of the most perplexing problems in palaeoclimate research. Here we use complex demodulation to examine the phase evolution of precession and semiprecession cycles--the latter of which are phase-coupled to both precession and eccentricity--in the tropical and extratropical Atlantic Ocean. We find that about 1.5 Myr ago, tropical semiprecession cycles (with periods of about 11.5 kyr) started to propagate to higher latitudes, coincident with a growing amplitude envelope of the 100-kyr cycles. Evidence from numerical models suggests that cycles of about 10 kyr in length may be required to explain the high amplitude of the 100-kyr cycles. Combining our results with consideration of a modern analogue, we conclude that increased heat flow across the equator or from the tropics to higher latitudes around 1.5 Myr ago strengthened the semiprecession cycle in the Northern Hemisphere, and triggered the transition to sustained 100-kyr glacial cycles.     

田洋玛珥湖中更新世以来磁化率特征及其环境意义

 对雷州半岛东南部的田洋玛珥湖TYC孔前40 m岩芯进行了研究,结果表明,磁化率与孢粉有很好的对应关系,因而磁化率值的高低变化能够作为该区气候环境变化的替代指标。沉积物磁化率与气候变化的关系为：磁化率的低值与气候暖湿对应;磁化率的高值则与气候寒冷或温凉相对应。中更新世以来,田洋玛珥湖气候环境演化经历了9个不同的阶段：346~301.4 kaBP,气候相对暖湿。301.4~248.8 kaBP,气候寒冷干燥。248.8~188.8 kaBP,气候相对暖湿。188.8~125.2 kaBP,气候寒冷干燥。125.2~69.3 kaBP,气候较为暖湿。69.3~40.43 kaBP,气候偏凉。40.43~25.5 kaBP,气候偏凉但较上阶段温度低,此时玛珥湖呈现出沼泽化过渡阶段。25.5~10.8 kaBP,气候寒冷干燥,玛珥湖干枯成为干玛珥湖。10.8 kaBP以来,由于后期人类活动对玛珥湖的改造,致使磁化率值不断升高。     

撒哈拉以南非洲地区林木资源投资风险分析

 “一带一路”发展倡议为沿线国家优势互补、开拓发展提供了新的机遇,是国际合作的新平台。撒哈拉以南非洲地区林木资源丰富,是中国“一带一路”发展倡议大背景下的重要合作方向,增强与该地区林木资源投资合作建设,是推动“一带一路”建设的重要内容。本文综合考虑了该地区林木资源禀赋、社会经济因素、自然地理因素及政治外交因素等,基于多级模糊综合评价方法构建了撒哈拉以南非洲地区林木资源投资风险分析模型,通过评价指标选取、指标体系建立和指标权重分析,对主控投资因素进行研究和评价分析,对该地区林木资源投资风险分析进行了综合评估。     

Extended megadroughts in the southwestern United States during Pleistocene interglacials

The potential for increased drought frequency and severity linked to anthropogenic climate change in the semi-arid regions of the southwestern United States (US) is a serious concern. Multi-year droughts during the instrumental period and decadal-length droughts of the past two millennia were shorter and climatically different from the future permanent, 'dust-bowl-like' megadrought conditions, lasting decades to a century, that are predicted as a consequence of warming. So far, it has been unclear whether or not such megadroughts occurred in the southwestern US, and, if so, with what regularity and intensity. Here we show that periods of aridity lasting centuries to millennia occurred in the southwestern US during mid-Pleistocene interglacials. Using molecular palaeotemperature proxies to reconstruct the mean annual temperature (MAT) in mid-Pleistocene lacustrine sediment from the Valles Caldera, New Mexico, we found that the driest conditions occurred during the warmest phases of interglacials, when the MAT was comparable to or higher than the modern MAT. A collapse of drought-tolerant C(4) plant communities during these warm, dry intervals indicates a significant reduction in summer precipitation, possibly in response to a poleward migration of the subtropical dry zone. Three MAT cycles ～2?°C in amplitude occurred within Marine Isotope Stage (MIS) 11 and seem to correspond to the muted precessional cycles within this interglacial. In comparison with MIS 11, MIS 13 experienced higher precessional-cycle amplitudes, larger variations in MAT (4-6?°C) and a longer period of extended warmth, suggesting that local insolation variations were important to interglacial climatic variability in the southwestern US. Comparison of the early MIS 11 climate record with the Holocene record shows many similarities and implies that, in the absence of anthropogenic forcing, the region should be entering a cooler and wetter phase.