New data on the correlation of skarn and gold mineralization at the Tardan deposit (northeastern Tuva)

Gold mineralization of the Tardan deposit is of different spatial occurrences and is related to different hydrothermal-metasomatic formations, the main ones being skarn-magnetite bodies, metasomatites of mineralized crush zones, and metasomatites of argillizitic-rock association. The formation of gold mineralization was a multistage process related to the repeated magmatism of the Tannu-Ola complex. It took place in a wide temperature range (400–150 °C), which determined the diversity of produced mineral assemblages. The gold mineralization associated with magnetite bodies shows a spatial correlation with magnesian and calcareous skarns and is localized in plagiogranites and gabbro-diorites of the Tannu-Ola complex intruded in the Late Ordovician. Gold mineralization that occurs in crush zones and along the fault sutures in moderate- and low-temperature hydrothermal-metasomatic rocks (propylites, beresites, serpentinites, and argillizites) formed somewhat later than skarns as a result of the intrusion of granite dike bodies. Comparative analysis of different types of gold mineralization showed both a change of mineral assemblages of the gold mineralization during the ore formation and some geochemical difference between gold and gold-bearing ores. In passing from early to late occurrences of native gold, its fineness decreases, the contents of admixtures correspondingly increase, and the gold composition changes. Gold of high-temperature rocks is rich in Cu (up to 17%), and gold of low-temperatures rocks has higher contents of Ag and Hg.     

四川德格错阿金矿特征与矿床成因初析

错阿金矿床赋存于理塘义敦群上三叠统瓦能组变基性火山岩中,金矿体受次级北北西-近南北向韧性-脆韧性剪切变质带控制,与金矿化有关蚀变主要为黄铁矿化、辉锑矿化和硅化、碳酸盐化、金云母化及石墨化。矿床成因为蚀变构造型。甘孜-理塘断裂带北段嗄拉、错阿、海子口三个矿化集中区内大部份化探异常具有面积大、强度高、梯度变化大、元素组合好等特点,具有很好的找矿前景。     

基于智能体的鄱阳湖区钉螺生长模型及其模拟研究

基于复杂自适应系统理论,采用自下而上的基于智能体的建模分析方法,模拟了自然环境与钉螺生长相互作用导致的钉螺生长的主要行为特征、生命状态和数量变化,开发实现了模拟模型,同时输入实测数据进行实例模拟,结果表明该模型能够作为血吸虫病防控工作中钉螺数量估测的一种辅助实验方法和工具.     

追忆李四光对防震减灾的贡献,以系统整体观指导防震应急

笔者在追忆李四光地震科学和防震减灾指导思想的基础上,提出了以系统整体观指导防震应急的新论点,包括:运用地壳运动整体观研究地震规律;应用地震预测整体观进行地震预测;划分活动性构造体系,研究构造活动性;加强综合监测,研究各种地震前兆和相关的自然变异的发展趋势;圈定地震风险区,制定防震应急预案等.并结合中国的实际情况进行了论述.     

Preserved paleo-oceanic plateaus in accretionary complexes: Implications for the contributions of the Pacific superplume to global environmental change

We have reinvestigated the mid-Cretaceous plume pulse in relation to paleo-oceanic plateaus from accretionary prisms in the circum-Pacific region, and we have correlated the Pacific superplume activity with catastrophic environmental changes since the Neoproterozoic. The Paleo-oceanic plateaus are dated at 75–150 Ma; they were generated in the Pacific superplume region and are preserved in accretionary prisms. The volcanic edifice composed of both modern and paleo-oceanic plateaus is up to 10.7 × 10⁶ km² in area and 19.1 × 10⁷ km³ in volume. The degassing rate of CO₂ (0.82 − 1.1 × 10¹⁸ mol/m.y.) suggests a significant impact on Cretaceous global warming. The synchronous occurrence of paleo-oceanic plateaus in accretionary complexes indicates that Pacific superplume pulse activities roughly coincided at the Permo-Triassic boundary and the Vendian–Cambrian boundary interval. The CO₂ expelled by the Pacific superplume probably contributed to environmental catastrophes. The initiation of the Pacific superplume contributed to the snowball Earth event near the Vendian–Cambrian boundary; this was one of the most dramatic events in Earth's history. The scale of the Pacific superplume activity roughly corresponds to the scale of drastic environmental change.     

塔里木盆地巴楚地区中奥陶统一间房组露头礁滩复合体储层地质建模及其对塔中地区油气勘探的启示

通过1：5万礁滩复合体地质填图,在巴楚地区共发现大小不等的礁滩复合体90余个,层位为中奥陶统一间房组二段．台缘为礁滩复合体密集发育区,礁滩体规模大,台内为礁滩复合体零星发育区,礁滩体规模小。通过对6个典型礁滩复合体的解剖,研究了礁滩复合体的微相类型、组合和各微相的岩石特征、生物群落,并对其生长发育阶段进行了分析。根据6个典型礁滩复合体及礁间的大量铸体薄片鉴定和物性资料,分析了储层的特征、成因和非均质性,建立了台缘礁及礁间、台内礁及礁间2种背景条件下的储层地质模型。巴楚地区露头礁滩复合体储层地质模型对塔中地区上奥陶统良里塔格组礁滩复合体的勘探具有重要的指导意义,并为勘探实践所证实。     

鄂尔多斯高原植被生态分区及其水文地质意义

保护生态环境是鄂尔多斯高原地下水可持续开发利用中亟待解决的问题。在查清植被生态群落分布特征的基础上,通过分析植被演替的自然驱动因素,将鄂尔多斯高原的植被生态划分为基岩台地植被生态水文地质区、沙盖基岩植被生态水文地质区、沙地植被生态水文地质区和滩地植被生态水文地质区。结果表明,气象和地形地貌控制着区内植被生态的总体分布格局,包气带和地下水因素控制着植被生态的演替,沙地植被生态和滩地植被生态的生长发育与地下水关系密切,是地下水开发时保护植被生态的靶区。     

陕西小秦岭华阳川韧性剪切带的特征 及其区域构造意义

陕西小秦岭华阳川韧性剪切带发育在新太古界太华群之中,野外调研和显微构造观察结果表明,该韧性剪切带是由构造片岩、眼球状片麻岩组成的深层次韧性剪切带,具有逆冲兼左行走滑的斜冲特征。对韧性剪切带构造片岩黑云母进行^40Ar／^39Ar同位素定年,获得坪年龄为419M±0．6Ma,反等时线年龄为417Ma±0．8Ma。认为华阳川韧性剪切带及其相应的小秦岭区域主导构造变形是发生于419Ma左右的秦岭加里东事件的结果。     

Progresses in the ice formation of glaciers in China

Glaciers, formed by snowfall and characterized by movement and size, are the most sensitive indicators to climate change. The ice formation of glaciers (the processes, mechanisms and results of transformation from snow to ice) can indicate the growth condition, the formation process and the physical characteristics of glaciers. Its spatial variation can also reflect glacier change, and further reveal climate change. Studies on ice formation of glaciers in China were initiated in 1962, when Xie and others studied the ice formation of Glacier No.1 at the Urumqi River head, Tianshan Mountain. Other researchersfollowed suit and did studies on ice formation of glaciers in Qilian Mountain. As time goes by, the concept of ice formation came into being in China. This paper reviews the development history of glacier zones, and the studies of ice formation of glaciers in China since the 1960s. These studies mainly focus on Qilian Mountain, Tianshan Mountain, Altay Mountain, and the western Kunlun Mountain, Himalaya Mountain, the southeastern Tibetan and Hengduan Mountains. The paper also discusses the significance of ice formation studies, the limitation and deficiency of previous studies, and the prospects and suggestions for future studies. __________ Translated from Advances in Earth Science, 2007, 22(4): 386–395 [译自: 地球科学进展]