塔中地区石炭系层序地层分析与沉积相研究

通过层序地层学的划分与对比，将塔中地区石炭系划分为4个沉积层序．该区石炭系沉积相主要以滨海相沉积为主，在滨海相沉积背景下出现了海滩与潮滩两种不同的沉积体系．此外还发育有台地相、三角洲及辫状河三角洲沉积体系等，沉积相按其发育时间和平面上的展布特征，可以归为4类沉积体系组合：海滩(前滨、临滨)-局限台地组合、(潟湖-)潮滩(潮上、潮间及潮下)-局限台地组合、辫状河．(辫状)三角洲．局限台地组合、台地潮坪-局限台地-开阔台地组合。沉积环境经历了滨海-局限台地-滨海-局限台地的演变过程，发育砂岩和碳酸盐岩两类储层，并发育有良好的区域性盖层。     

新议异珊瑚的隔壁和横板

本文根据近年来我国的异珊瑚资料,将其某些特征归结如下:1.隔壁自个体体壁至中央发育;2.原始隔壁数目可能是五(或四)个;3.后生隔壁数目尚无规律,其趋势是由少增多插入个体各区域内,一般侧区早发育后生隔壁,且数目较其他区域要多;4.隔壁有分级现象,末端也可游离;5.横板发育,有上穹、平坦、下凹三种形态;6.可分为完整横板和不完整横板两种类型;7.横板排列间距不仅因种类而异,同一个体中也有中央与边缘之别。另外,对异珊瑚目中的六个属也有一定演化关系可寻。     

利用数据挖掘技术识别深层火山岩气层

石炭系火山岩的低渗透气藏具有的埋藏深、成因复杂、类型多、分布广、三孔隙度曲线响应特征不明显等特点,并且主要的四种火山岩气藏：玄武岩、安山岩、英安岩、流纹岩的密度和纵波时差测井值差别较大,因此使基于三孔隙度测井资料的一系列识别气层的有效方法在该盆地石炭系火山岩气层的识别中无明显效果.数据挖掘技术从数据的角度出发,在进一步丰富岩心、测井和试油资料的前提下,利用数据挖掘技术中的聚类分析和关联分析获取核心参数和数据之间的内在联系,用决策树提取预测火山岩气层的模型.该方法充分利用已有的数据资料,用数学分析方法遍历寻找对识别火山岩气层有用的信息,而不仅仅依靠三孔隙度和电阻率曲线,并且消除了岩性的影响,因此获得了较高的识别率.     

Petrogenesis and tectonic implications of early Carboniferous alkaline volcanic rocks in Karamay region of West Junggar,Northwest China

ABSTRACT

Zircon U–Pb geochronological and geochemical analyses are reported for a suite of the early Carboniferous volcanic rocks from West Junggar (Northwest China), southern Central Asian Orogenic Belt (CAOB), with the aim to investigate the sources, petrogenesis, and tectonic implications. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb analysis from an andesite yielded concordant weighted mean ²⁰⁶Pb/²³⁸U age of 345 ± 3 Ma, indicating the presence of early Carboniferous volcanic rocks in West Junggar. The early Carboniferous volcanic rocks consist of basalt, basaltic andesite, and andesite. Geochemically, all the samples bear the signature of ocean island basalt (OIB), and are characterized by alkaline affinity with minor variations in SiO₂ compositions (45.13–53.05 wt.%), high concentrations of Na₂O + K₂O (5.08–8.89 wt.%) and TiO₂ (1.71–3.35 wt.%), and LREE enrichment and HREE depletion ((La/Yb)_N = 7.1–12.4), with weak Eu anomalies (Eu/Eu* = 0.9–1.1) and no obvious Nb, Ta, and Ti negative anomalies. These features suggest that the early Carboniferous volcanic rocks were derived from an OIB-related source that consists of oceanic lithosphere with ~1–3% degree partial melting of garnet lherzolite. From these observations, in combination with previous work, we conclude that the early Carboniferous alkaline volcanic rocks in Karamay region formed by upwelling of asthenospheric mantle through a slab window in a forearc setting during consumption of the West Junggar Ocean. Meanwhile, seamounts, which formed in the Late Devonian and were accreted and subducted in Karamay arc, also brought geological effects in the subduction zone.     

轮南地区石炭系砂泥岩段S3层储层特征与评价

从沉积环境入手,依据岩芯、铸体薄片、测井解释、压汞试验、物性分析等资料,并结合区域地质背景对塔里木盆地北部轮南地区石炭统卡拉沙依组砂泥岩段S3砂组进行了研究。结果表明：该区砂泥岩段S3砂组优质储层的岩性为岩屑砂岩、含砾不等粒砂岩、粉砂岩等;储层孔隙类型以粒间孔、粒间溶孔为主,发育少量粒缘缝;碳酸盐岩胶结物在轮南地区砂泥岩段S3砂组储层中较为普遍;钙质体积分数较高。钙质主要以方解石、铁方解石、铁白云石胶结物的形式存在;优质储层的分布受控于沉积环境,集中发育在砂泥岩段S3砂组上部的三角洲前缘相的分流河道与前缘席状砂和砂泥岩段S3砂组下部潮坪相的潮道和砂坪微相里,所以这些区域是油气勘探的重点目标区。     

Carboniferous Highly Fractionated I‐type Granites from the Kalamaili Fault Zone,Eastern Xinjiang,NW China: Petrogenesis and Tectonic Implications

Carboniferous magmatism is one of the most important tectonothermal events in the Central Asian Orogenic Belt(CAOB). However, the final closure time of the Kalamaili Ocean between East Junggar and Harlik Mountain is still debated. Early Carboniferous(332 Ma) and late Carboniferous(307–298 Ma) granitic magmatism from Kalamaili fault zone have been recognized by LA-ICP-MS zircon U-Pb dating. They are both metaluminous highly fractionated I-type and belong to the high-K calc-alkaline. The granitoids for early Carboniferous have zircon ε_(Hf)(t) values of-5.1 to +8.5 with Hf model ages(T_(DM2)) of 1.78–0.83 Ga, suggesting a mixed magma source of juvenile material with old continental crust. Furthermore, those for late Carboniferous have much younger heterogeneous zircon ε_(Hf)(t) values(+5.1 to +13.6) with Hf model ages(T_(DM2)=1.03–0.45 Ga) that are also indicative of juvenile components with a small involvement of old continental crust. Based on whole-rock geochemical and zircon isotopic features, these high-K granitoids were derived from melting of heterogeneous crustal sources or through mixing of old continental crust with juvenile components and minor AFC(assimilation and fractional crystallization). The juvenile components probably originated from underplated basaltic magmas in response to asthenospheric upwelling. These Carboniferous highly fractionated granites in the Kalamaili fault zone were probably emplaced in a post-collisional extensional setting and suggested vertical continental crustal growth in the southern CAOB, which is the same or like most granitoids in CAOB. This study provides new evidence for determining the post-accretionary evolution of the southern CAOB. In combination with data from other granitoids in these two terranes, the Early Carboniferous Heiguniangshan pluton represents the initial record of post-collisional environment, suggesting that the final collision between the East Junggar and Harlik Mountain might have occurred before 332 Ma.