新疆福海县蒙库地区早二叠世侵入岩成因与成岩方式探讨

新疆福海县蒙库地区早二叠世侵入岩序列主要侵位于中元古界苏普特岩群、震旦系富蕴群与上石炭统喀喇额尔齐斯组地层中,延伸不连续,呈单个岩体出露,出露面积均较小,总体上呈北西-南东向、条带状分布,与区域构造线方向一致,反映了区域构造对侵入体的的控制作用。岩体平面上呈平行舌状,岩体与围岩发生较强的交代作用,其边缘附近发育大量大小不一的围岩捕虏体,并见岩枝贯入围岩。文章就蒙库地区早二叠世侵入岩成因与成岩方式进行了探讨。     

造山带与盆地正负相伴生：塔里木盆地构造风格剖析

岩石层会聚地区，形变作用的体现是以造山带与盆地正负相伴生组成的地质景观为特色，青藏特提斯“造山拼合体”后陆的塔里木盆地就是一典型实例，笔者依据盆内区域地震地质解释断面反映的盆地实体形变特征及有限的钻井资料，结合盆缘地质露头，剖析塔里木盆地构造地史及其形变风格，认为，塔里木盆地构造演化受控于古亚洲与特提斯两大构造域，因其形变风格各异，导致盆内垂向上呈古褶隆与类前陆和新造山带与前陆盆地双层地质结构。     

REE Mineralization of Weathered Crust and Clay Sediment on Granitic Rocks in the Sanyo Belt,SW Japan and the Southern Jiangxi Province,China

Rare earth element (REE) geochemistry and mineralogy have been studied in the weathered crusts derived from the Early Yanshanian (Jurassic) biotite granites of Dabu and Dingnan, as well as in the Indosinian (Permian) muscovite–biotite granite of Aigao in southern Jiangxi province, China, and the weathered crusts and clay sediments on biotite granites in the Sanyo belt, SW Japan, that is, Okayama, Tanakami, and Naegi areas. In all of the weathered crusts, biotite and plagioclase commonly tend to decrease toward the upper part of the profile, whereas kaolinite and residual quartz and K‐feldspar increase. The weathered crusts of the Dingnan granites and some Naegi granites, which are characterized by the enrichment in light REE (LREE) in C horizons, have higher total REE (ΣREE) content than the parent REE‐enriched granites. Weathering of LREE‐bearing apatite and fluorocarbonates in the Dingnan granites and allanite and apatite in some Naegi granites may account for the leaching of LREE at the B horizons. The leached LREE must result in subsequent enrichment of LREE in the C horizons. The enrichment is probably associated with mainly adsorption onto kaolinite and partly formation of possible secondary LREE‐bearing minerals. In Japan it was found that REE mineralization occurs not in the weathered granitic crusts but in reworked clay sediments, especially kaolinite‐rich layers, derived mainly from the weathering materials of REE‐enriched granitic rocks. The clay sediments are more enriched in LREE, which likely adsorbed onto kaolinite. Concentration of heavy REE within almost all the weathered crusts and clay sediments, however, may reflect mainly residual REE‐bearing minerals such as zircon, which originated in the parent granitic rocks. The findings of the present study support the three processes for fractionation of the REE during weathering: (i) selective leaching of rocks containing both stable and unstable REE‐bearing minerals; (ii) adsorption onto clay minerals; and (iii) presence of possible secondary LREE‐bearing minerals.     

广西涠洲岛南湾火山喷发特征

涠洲岛是北部湾内的一座火山岛, 火山熔岩构筑了该岛的基底, 岛南端的南湾火山喷发物形成了涠洲岛现代火山地貌.南湾火山喷发以岩浆喷发和射气岩浆喷发交替进行为特征, 火山碎屑岩和基浪堆积物向岛北延伸, 覆盖了大半个涠洲岛.选取了鳄鱼嘴和猪仔岛2个典型剖面, 对南湾火山喷发活动进行详细的观察和描述, 发现了诸如爬升层理、大型低角度交错层理和板状层理等射气岩浆喷发成因的基浪堆积物中特有的构造, 并且观察到射气岩浆作用的指相物质——增生火山砾.所有这些现象都反映了南湾火山是射气与岩浆交替喷发成因的复合火山, 其中射气岩浆喷发占据重要地位, 而喷发中心位于南湾海中.      

长白山天池火山公元1014-1019年大喷发的历史记录

长白山火山是世界著名的火山之一，是我国规模最大、最具有潜在喷发危险的一座近代活动火山。目前，国内外许多火山学者为了研究长白山火山最近一次大喷发年代问题，做了大量工作，并取得了一些年代资料，但一直未取得有关这次大喷发历史记载的证实。笔者等通过再次收集和查阅了大量文史古籍资料，通过整理、筛选、考证、对比和分析处理，首次发现了长白山（白头山）火山，于公元1014～1019年间一次大喷发的历史记载。这对于研究长白山火山喷发历史具有重要的意义。     

兰聊断裂南段构造样式与最新活动性分析

兰聊断裂南段构造样式复杂,分段活动特征明显。已有学者针对兰聊断裂的研究,主要集中在范县—东明县一带,而兰聊断裂南段的构造样式与最新活动性研究匮乏。为此采用地震反射剖面与钻孔联合剖面探测方法,对兰聊断裂南段进行较系统地分析,认为兰聊断裂南段构造样式为伸展走滑断裂尾端“马尾扇”结构,其最新活动时代为中更新世中晚期,晚更新世以来未活动,中更新世最大滑动速率为0.061 mm/a,据此判断兰聊断裂南段为中更新世断裂。     

长白山天池火山双岩浆房岩浆作用与互动式喷发

广义的长白山火山在我国境内包括天池火山、望天鹅火山、图们江火山和龙岗火山,是我国最大的第四纪火山岩分布区。长白山各个火山区的火山活动具有此起彼伏的穿时性特征,天池火山之下地壳和地幔两个岩浆房具有上下呼应、互动式喷发之特点。一方面来自地幔的钾质粗面玄武岩浆直接喷出地表,在天池火山锥体内外形成诸多小火山渣锥;另一方面钾质粗面玄武岩浆持续补给地壳岩浆房,发生岩浆分离结晶作用和混合作用,形成双峰式火山岩特征并触发千年大喷发。西太平洋板块俯冲-东北亚大陆弧后引张是长白山天池火山喷发的动力学机制。     

准噶尔盆地车排子地区新村油田石炭系构造特征与成藏条件

通过对准噶尔盆地车排子地区新村油田石炭系构造特征、储层、油气分布特征、主要油藏类型及其成藏条件的研究,建立了该区成藏综合模式。结果表明,研究区总体上处于构造斜坡带,具有北高南低、西高东低、南北分块的构造特征,地层产状平缓;研究区在石炭纪处于区域拉张构造应力背景,并在拉张应力作用下形成以北东—南西向展布为主的拉张型断裂组合样式;研究区大部分地区地层等高线平直,不利于形成背斜构造圈闭,但各级断裂发育,为形成断层遮挡圈闭提供了有利条件,同时也可作为油气运移的通道。依据石炭系断裂分布、断裂模式及其组合,将研究区的断裂划分为复合地垒系统、复合地堑系统和零星断裂系统。控制研究区油气运聚成藏的主要地质因素是断裂、裂缝及岩性变化或物性封堵。     

挤压断裂构造样式地震解释

挤压构造的动力学为板块与板块碰撞形成造山带,在造山带一侧或造山带内部形成挤压型盆地,这些盆地在挤压应力作用下,形成叠瓦逆冲、复合逆冲、多层次滑脱逆冲、多产状逆冲断裂构造组合。文中对与挤压逆冲有关的褶皱构造样式——断弯、断展、断滑褶皱构造进行了描述,指出在加强非背斜构造样式勘探的同时,也应加强背斜构造样式的勘探。油气资料显示80%～90%的油气生产来自背斜构造样式的油气田,面积大、幅度高的挤压构造是形成大、中型油气藏的地质条件。     

The Petrology and Geochemistry of the Aniakchak Caldera-forming Ignimbrite, Aleutian Arc, Alaska

Aniakchak caldera, Alaska, produced a compositionally heterogeneousignimbrite 3400 years ago, which changes from rhyodacitic atthe base to andesitic at the top of the eruptive sequence. Interpretationsof compositionally heterogeneous ignimbrites typically includeeither in situ fractional crystallization of mafic magma andgeneration of a stratified magma body or replenishment of asilicic magma chamber by mafic inputs. Another possibility,silicic replenishment of a more mafic chamber, exists. Geochemicalcharacteristics of the caldera-forming rhyodacite and severallate pre-caldera rhyodacites indicate independent origins foreach, within a maximum of 5000 years prior to caldera formation.Isotopic considerations preclude derivation of the caldera-formingrhyodacite from the caldera-forming andesite. However, the caldera-formingrhyodacite can be explained as the residual liquid of a mostlycrystallized basalt, with addition of crustal material. TheAniakchak andesite probably formed in a shallow chamber by successivemixing events involving small volumes of basalt and rhyodacite,together with contamination. The pre-caldera rhyodacites representerupted portions of intruding silicic magma, whereas anotherportion homogenized with the resident mafic magma. The caldera-formingevent reflects a large influx of rhyodacite, which erupted beforesignificant mixing occurred and also triggered draining of muchof the andesitic magma from the chamber. KEY WORDS: Aniakchak; caldera-forming eruption; geochemistry; ignimbrite; silicic replenishment