In situ zircon Hf isotopic, U-Pb age and trace element study of monzonite xenoliths from Pingquan and Fuxin basalts: Tracking the thermal events of 169 Ma and 107 Ma in Yanliao area

K-Ar ages of the Mesozoic (92-100 Ma) Fuxin alkalic basalts (western Liaoning Province) and the Tertiary (23-45 Ma) Pingquan alkalic basalts (eastern Hebei Province), and the results of in situ zircon U-Pb dating, Hf isotope and the trace elements from three monzonite xenoliths carried in the alkalic basalts are reported. The crust-mantle interaction occurring in the Yanshan intracontinental orogenic belt is also discussed. Fuxin zircons show highly uniform U-Pb age ((1693) Ma). More than 95% Pingquan zircons display the age of (107?0) Ma except two are 2491 Ma and 513 Ma respectively. Zircons with the ages of (169?) Ma have eHf close to zero. eHf of the zircons with the ages of (10710) Ma are mainly at -11.5--16.3, showing the crustal derivation. Fuxin zircons contain low Nb, Ta, Sr, Th, U contents, low and narrow Hf model ages (0.87-1.00 Ga), which reflect that the source materials of the monzonite xenoliths are young to Pingquan (focus at (1.280.08) Ga). High contents of the incompatible elements, and wide range of Hf model ages (0.89-2.56 Ga) in Pingquan zircons suggest a more complex source and the highly crustal maturity in their petrogenesis. Comprehensive information including the published data indicates that J3-K1 is the key period of the deep processes and shallow tectonic reverse in the Yanliao area. However, the processes were highly heterogeneous in spatial and in temporal.

An Updated Review of the Middle-Late Jurassic Yanliao Biota: Chronology,Taphonomy,Paleontology and Paleoecology

The northeastern Chinese Yanliao Biota （sometimes called the Daohugou Biota） comprises numerous, frequently spectacular fossils of non-marine organisms, occurring in Middle-Upper Jurassic strata in western Liaoning, northern Hebei, and southeastern Inner Mongolia. The biota lasted for about 10 million years, divided into two phases： the Bathonian-Callovian Daohugou phase （about 168-164 million years ago） and the Oxfordian Linglongta phase （164-159 million years ago）. The Yanliao fossils are often taphonomically exceptional （many vertebrate skeletons, for example, are complete and accompanied by preserved integumentary features）, and not only are taxonomically diverse but also include the oldest known representatives of many groups of plants, invertebrates, and vertebrates. These fossils have provided significant new information regarding the origins and early evolution of such clades as fleas, birds, and mammals, in addition to the evolution of some major biological structures such as feathers, and have demonstrated the existence of a complex terrestrial ecosystem in northeast China around the time of the Middle-Late Jurassic boundary.

冀东-辽西主要金矿矿集区地质特征的差异性与成矿作用的统一性探析

通过对燕辽成矿带东段冀东-辽西金矿床基础地质地球化学资料分析,结合区域构造演化和成矿时间及其分布空间的特异性,认为冀东-辽西金矿成矿物质具有相同的深来源特征,由于具体的构造背景不同而表现出矿床类型和就位空间的差异性,提出了燕辽裂陷槽是冀东-辽西金矿床空间分布的诱因,并提出冀东-辽西金成矿演化分为陆陆碰撞拼贴期（4.5~1.85Ga）、陆内裂陷巨厚沉积期（1.85~0.6Ga）、板内造山挤压隆升期（200~145Ma）、构造体制转换成矿期（145~100Ma）和成矿后的改造期（100Ma~至今）等5个统一阶段的结论性认识。

燕辽地区中生代火山活动对古环境的影响

采用红外光谱和电子探针分析方法,开展对华北克拉通北缘燕辽地区中生代火山岩中斑晶矿物包裹体地球化学成分研究,并具体分析了燕辽地区中生代火山活动对古环境所造成的重大影响。研究表明,从中生代早期至晚期,燕辽地区火山活动喷出气体及其气溶胶对古环境造成的影响具有明显不同的演化特征。从早到晚表现为:(1)南大岭期玄武质火山喷出的剧毒气体富集 S 与 Cl,它们导致火山区附近地表温度下降和酸雨形成;(2)髫髻山期安山质—粗面安山质火山喷发形成的气体以高含量的 H_2O 和 CO_2为特征,其对周围环境造成的影响是引起地表温度上升;(3)张家口期粗面质和流纹质火山作用喷出的剧毒气体富集 Cl 和 F 两组分,它们主要是破坏大气臭氧层和形成酸雨;(4)辽西义县期和九佛堂期中酸性火山活动喷入大气圈剧毒火山气体的 S、Cl 和 F 含量均较高,火山喷出的大量气体及其气溶胶与火山灰一起导致辽西中生代大量带毛恐龙和孔子鸟等脊椎动物集群死亡,并形成化石层。本文从火山气体及其气溶胶对古环境影响的角度初步分析了辽西地区出露大量中生代脊椎动物化石的原因。

Triassic alkaline intrusives in the Yanliao-Yinshan area:their chronology,Sr,Nd and Pb isotopic characteristics and their implication

Dated isotopic ages for 15 alkaline intrusives in the Yanliao-Yinshan area, ranging from 268 to 190 Ma, ten of which are from 250 to 208 Ma, indicate that most of them were formed in the Triassic Epoch. All the ENd(t) ratios from - 17.19 to -3.21 averaging -7.09, the ESr(t) ratios fmm 11.7 to71.5 averaging 36.63, and the Isr(t) ratios from 0.705 0 to 0.709 3 averaging 0.706 8, show their characteristics of enrichment. On the ENd (t) virus ESr(t) correlation diagram, the samples from these intmsives were plotted within the enriched mantle trend lines and just outside, demonstrating their close connection to materials from the enriched mantle reservoir, taking into account the same Pb isotopic composition as that of the mantle.

燕辽地区出土史前玉璧浅析

燕辽地区是史前玉器的重要出土地点,本文从燕辽地区史前时期出土玉璧入手,从型式分析、分期、制作与使用等多个方面进行梳理,归纳出这一地区史前时期玉璧的整体面貌和发展规律。

燕辽地区燕山期岩浆作用及热液型铀矿研究新进展

燕辽地区燕山期岩浆活动强烈,在时间上,从早到晚可划分出早侏罗世-中侏罗世早期、中侏罗世晚期-晚侏罗世早期、早白垩世早期、早白垩世晚期、晚白垩世5个期次,火山岩主体由早白垩世早期构成,侵入岩主体由中侏罗世晚期-晚侏罗世早期和早白垩世早期构成。燕辽地区主要以流纹岩-粗面岩组合为特征,为燕辽地区的岩浆岩分布及火山岩与铀成矿之间的关系研究奠定了良好的基础,也为火山活动有关的热液型铀矿的寻找提供了方向。