贵州织金互层型稀土磷块岩工艺矿物学研究

通过对贵州织金稀土磷矿中高品位磷质条带和白云质条带两类矿石的工艺矿物学研究,查明了矿石的矿物组成、稀土元素和微量元素的赋存特性等,着重研究在不同粒级下的不同化学组分的分布情况、富集规律及相互关系,从降Si、Mg、Fe角度考虑,为原矿的破碎工序和选矿方案选择提供依据。研究结果表明,磷质条带属于高品位钙镁质磷块岩,P₂O₅平均品位为35%,w(MgO)平均为1.37%,w(SiO₂)平均为5.76%,磷灰石是主要的有用矿物,含量为74.95%,与白云石、石英、方解石、黄铁矿等矿石紧密镶嵌共生;白云质条带其P₂O₅品位平均为8.35%,Mg含量相对较高,w(MgO)平均为14.58%,w(SiO₂)平均为8.12%,白云质条带属于低品位钙镁质磷块岩,磷灰石是主要的有用矿物,含量22.99%,这种互层型磷块岩的主要脉石矿物有白云石、石英、黄铁矿等。     

吉林延边地区月山洞闪长岩岩体年代学、岩石地球化学及其地质意义

月山洞岩体位于吉林省延边地区,大地构造位置位于龙岗地块与吉黑造山带的交界处,岩性主要为闪长岩.LA-ICP-MS锆石U-Pb测年结果显示,月山洞岩体样品P₃B_6-2加权平均年龄为178.4±1.2 Ma,表明其岩体侵位时代为早侏罗世晚期.岩石地球化学特征上,月山洞岩体具有高Al富Na的特点,样品的Na₂O、K₂O、Al₂O₃、CaO、MgO、FeO_t、P₂O₅和TiO₂与SiO₂均呈明显的线性关系,表明在成岩过程中存在着辉石、磷灰石、磁铁矿等矿物的分离结晶作用.月山洞样品稀土含量中等,具有轻稀土元素相对富集,重稀土元素相对亏损的特点,且δEu值为0.67~1.04,显示出微弱的Eu负异常到微弱的正Eu异常.月山洞岩体亏损Nb、Ta、P和Ti等高场强元素,富集Cs、Rb、Ba和K等大离子亲石元素.其Nb/Ta、La/Nb和Th/Nb比值介于地壳和地幔平均值之间,显示了月山洞岩体岩浆具有壳幔混源的特点.结合月山洞岩体岩石地球化学特点和区域构造背景,认为该岩体构造背景应受到了太平洋板块俯冲的影响,同时也可能受到了古亚洲洋闭合后南北大陆持续碰撞的叠加影响.     

银额盆地赛尔亥那地区铀矿化特征及成因研究

银额盆地赛尔亥那地区发现的地表铀矿化带,前期认为是层间氧化铀成矿作用形成的砂岩型铀矿化,本次研究发现,赋矿岩石类型为含铀白云质磷质岩及含铀磷质粉砂岩。矿石中赋存大量的微晶磷灰石,呈微晶(粒径<1μm)集合体形式。全岩主微量分析显示U与P₂O₅、Ca O呈较好的正相关,磷灰石微区原位(LA-ICP-MS)主微量分析结果显示U与P₂O₅、Ca O、∑REE等均呈较好的正相关,高倍扫描电镜下未发现铀矿物,认为铀是以类质同象形式赋存在磷灰石中。铀矿石岩性岩相特征、磷灰石微区原位微量元素组合特征及共伴生矿物成因等表明,富铀磷灰石是在沉积成岩过程中,微生物参与作用下形成的。因此,赛尔亥那地区铀矿找矿思路应兼顾潜水-层间氧化型及沉积成岩型。     

黑龙江省太平岭地区下二叠统双桥子组岩石地球化学特征及其成矿意义

太平岭成矿带是黑龙江省重要的铜金多金属成矿带,矿床类型主要为中温热液脉型,也发育斑岩型、浅成低温热液型和岩浆熔离型.区内广泛发育的下二叠统双桥子组（P₁s）由泥质岩、粉砂岩及砂岩夹多层中酸性火山岩等组成.地层中Au、P、Fe等元素含量较高,近年来,在东宁县及穆棱市境内相继发现了陆角岭、五道沟-二十三公里等小型金矿床,金矿体均呈脉状产于P₁s中,但品位较低,直接影响到下一步找矿决策.在野外调查的基础上,利用岩石地球化学、X射线粉晶衍射以及有机碳分析等手段,对该地层岩石类型、沉积物源以及Au等成矿元素来源进行了分析,结果表明:岩石主量元素含量稳定,与PAAS相比,轻度亏损Al₂O₃、P₂O₅、CaO和MnO₂,中度亏损Na₂O、MgO、TiO₂和Fe₂O₃;微量元素除了Zn外,其他元素含量都较低;稀土元素总量与北美页岩相当,轻重稀土元素分异略低于北美页岩;主要矿物为粘土矿物（伊利石、绿泥石）和石英,另有不等量的钠长石、少量的碳酸盐矿物和黄铁矿,岩石TOC含量为0.22%~2.52%,平均值为1.10%;岩石中Au的含量与TOC和粘土矿物含量之间没有相关性.认为区内P₁s为碳质砂板岩,沉积物主要来源于石英质沉积岩的风化产物,少量来源于镁铁质和长英质火成岩,沉积于近岸环境,地层中高含量的金并不是成岩之后由流体携带而来并被岩石中富含的有机物或粘土矿物所吸附,而是同样来源于陆源风化产物,指示该区产于P₁s中的金矿并非层控型金矿床,而是受断层控制的热液脉型金矿床.      

云南中三叠世罗平生物群中首次发现牙形石齿串

通过对云南罗平中三叠统关岭组二段产罗平生物群的大凹子剖面进行厘米级牙形石样品的精细采样、处理与鉴定分析, 发现了丰富的牙形石齿串, 并拼绘出一个较完整的牙形石多分子器官属(P₁、S₀、S₁、S_2/3和M).成对的片形Neospathodiform形态分子占据P₁位置; 单个指掌状的Cypridodelliform形态分子占据S₀位置; 成对的Enantiognathiform、Hindeodelliform与Cypridodelliform形态分子分别占据器官属的S₁、S₂、S₃和M位置.      

沉积磷灰石形成中的生物有机质因素

本文研究了黔中磷块岩中磷灰石的化学成分、红外光谱、碳和硫同位素组成以及伴生微量元素和稀土元素地球化学特征,获得了若干生物有机质成因的证据.磷灰石红外光谱特征表明CO₃^2-和SO₄^2-以类质同象部分替代PO₄^2-而进入磷灰石晶格,而碳、硫同位素特征表明,这CO₃^2-及SO₄^2-的相当部分是由生物有机质分解演化而来;叠层石磷灰石的P₂O₅含量与亲生物微量元素关系非常密切,而非叠层石者关系不甚密切;稀土元素地球化学特征表明,磷灰石的形成具有两种既有联系又各不相同的作用机制,即直接的生物作用和间接的有机质作用.     

雪硅钙石的矿物学特征研究

研究发现,雪硅钙石是一种硅酸钙水化物.根据电子探针分析结果计算得到的化学式为（Ca_4.424K_0.021Mg_0.003）_4.448（Si_5.731Al_0.728）_6.465O₁₆（OH）₂·4H₂O,与经典化学式Ca₅Si₆O₁₆（OH）₂·4H₂O基本一致.通过X射线粉晶衍射结果分析认为,该雪硅钙石属于1.4 nm类型雪硅钙石.雪硅钙石矿物呈放射状纤维集合体,颗粒大小为0.2 mm×0.5 mm×0.3 mm,黄褐色,正低突起,最高干涉色为Ⅰ级黄,二轴晶正光性,光轴角为53°.     

黑云母的密度和主要成分在风化过程中的变化——以山东半岛院格庄花岗岩体风化壳为例

黑云母是相对容易化学风化的常见矿物,可作为地表岩石风化程度的指示剂。为了研究黑云母在化学风化过程中的物理性质和化学成分的变化,本文对采自烟台院格庄花岗岩体风化壳中的黑云母进行了系统分析。样品经过分选、密度测量、化学测试和XRD衍射分析,结果表明,黑云母随着风化程度的增强,其颜色从黑色渐变为褐色乃至红褐色,硬度变小,挠性增强,密度由3.00 g/cm³以上逐步减小至2.45 g/cm³以下。矿物结构面网间距变大,结构和主要成分变化引发矿物相转变,矿物种类由黑云母→云母型混层矿物→水黑云母-蛭石混层矿物→蛭石;随着风化程度的增强,黑云母中SiO₂、Al₂O₃和Na₂O的含量逐渐增多富集,而TFeO、MgO、MnO、TiO₂、K₂O、CaO和P₂O₅含量减少流失,流失强度依次为K>P>Mn>Mg>Ti>Fe>Ca,K流失最大可达90%以上,...     

太平洋中部富REY深海粘土的地球化学特征及REY富集机制

深海沉积物中的稀土资源是一种新发现的、潜在的海底稀土资源.对太平洋中部重力活塞取样获得的90个深海粘土样品的矿物组分、常量和稀土化学分析结果进行了系统分析,并与中北太平洋以及西北太平洋南鸟岛附近海域深海沉积物稀土元素地球化学特征进行了对比.研究结果表明:太平洋中部深海粘土以富含沸石、富P及富REY为特征,其碎屑矿物中含有较多的鱼牙骨,其P₂O₅与CaO之间、P₂O₅、CaO与∑REY之间呈良好的正相关关系;其稀土分布模式表现为明显的Ce负异常、一定程度的重稀土元素富集和Y正异常.太平洋中部深海粘土REY富集的主要原因是深海粘土中含有过量的磷酸盐组分,推测过量的磷酸盐组分是由于深海粘土中鱼牙骨碎屑的加入引起的.在北太平洋海域,未受到热液活动影响的条件下,富REY的深海沉积物的稀土元素富集机制具有统一性和普遍性,可以归纳为深海沉积物中高REY磷酸盐的混入作用.      

河南省巩义铝土矿地球化学特征分析

龙门-巩义地区是河南省铝土矿成矿带之一.通过对巩义铝土矿主要成分化学测试,研究分析铝土矿床化学元素变化规律.结果表明：铝土矿矿石主要矿物成分为一水硬铝石(含量45%～95%),其次为高岭石、伊利石等(含量4%～25%),含少量菱铁矿、黄铁矿、方解石、白云石等,微量矿物有锆石、磷灰石等.矿石的主要化学成分为Al₂O₃、SiO₂、Fe₂O₃、TiO₂、S,共占总成分的83.42%.其中,Al₂O₃含量40.46%～77.59%,平均60.68%;SiO₂1.00%～29.54%,平均14.07%;铝硅比值(A/S)1.8～65.1,平均4.3.在不同埋深条件下,相对深度越大,Al₂O₃的含量值及A/S值相对越大.该区域的化学风化指数(CIA)值可达到91.16,指示本区含铝岩系遭受了强烈的化学风化作用.     

Pressure effect on Ti- or P-rich accessory mineral saturation in evolved granitic melts with differing K2O/Na2O ratios

The solubility of Ti- and P-rich accessory minerals has been examined as a function of pressure and K₂O/Na₂O ratio in two series of highly evolved silicate systems. These systems correspond to (a) alkaline, varying from alkaline to peralkaline with increasing K₂O/Na₂O ratio; and (b) strongly metaluminous (essentially trondhjemitic at the lowest K₂O/Na₂O ratio) and remaining metaluminous with increasing K₂O/Na₂O ratio (to 3). The experiments were conducted at a fixed temperature of 1000 °C, with water contents varying from 5 wt.% at low pressure (0.5 GPa), increasing through 5–10 wt.% at 1.5–2.5 GPa to 10 wt.% at 3.5 GPa. Pressure was extended outside the normal crustal range, so that the results may also be applied to derivation of hydrous silicic melts from subducted oceanic crust.

For the alkaline composition series, the TiO₂ content of the melt at Ti-rich mineral saturation decreases with increasing pressure but is unchanged with increasing K content (at fixed pressure). The P₂O₅ content of the alkaline melts at apatite saturation increases with increased pressure at 3.5 GPa only, but decreases with increasing K content (and peralkalinity). For the metaluminous composition series (termed as “trondhjemite-based series” (T series)), the TiO₂ content of the melt at Ti-rich mineral saturation decreases with increasing pressure and with increasing K content (at fixed pressure). The P₂O₅ content of the T series melts at apatite saturation is unchanged with increasing pressure, but decreases with increasing K content. The contrasting results for P and Ti saturation levels, as a function of pressure in both compositions, point to contrasting behaviour of Ti and P in the structure of evolved silicate melts. Ti content at Ti-rich mineral saturation is lower in the alkaline compared with the T series at 0.5 GPa, but is similar at higher pressures, whereas P content at apatite saturation is lower in the T series at all pressures studied. The results have application to A-type granite suites that are alkaline to peralkaline, and to I-type metaluminous suites that frequently exhibit differing K₂O/Na₂O ratios from one suite to another.     

Coupled redox transformations of catechol and cerium at the surface of a cerium(III) phosphate mineral

Highly insoluble Ce-bearing phosphate minerals form by weathering of apatite [Ca₅(PO₄)₃.(OH,F,Cl)], and are important phosphorous repositories in soils. Although these phases can be dissolved via biologically-mediated pathways, the dissolution mechanisms are poorly understood. In this paper we report spectroscopic evidence to support coupling of redox transformations of organic carbon and cerium during the reaction of rhabdophane (CePO₄·H₂O) and catechol, a ubiquitous biogenic compound, at pH 5. Results show that the oxic–anoxic conditions influence the mineral dissolution behavior. Under anoxic conditions, the release of P and Ce occurs stoichiometrically. In contrast, under oxic conditions, the mineral dissolution behavior is incongruent, with dissolving Ce³⁺ ions oxidizing to CeO₂. Reaction product analysis shows the formation of CO₂, polymeric C, and oxalate and malate. The presence of more complex forms of organic carbon was also confirmed. Near edge X-ray absorption fine structure spectroscopy measurements at Ce-M_4,5 and C-K absorption edges on reacted CePO₄·H₂O samples in the absence or presence of catechol and dissolved oxygen confirm that (1) the mineral surface converts to the oxide during this reaction, while full oxidation is limited to the near-surface region only; (2) the Ce valence remains unchanged when the reaction between CePO₄·H₂O and O₂ but in the absence of catechol. Carbon K-edge spectra acquired from rhabdophane reacted with catechol under oxic conditions show spectral features before and after reaction that are considerably different from catechol, indicating the formation of more complex organic molecules. Decreases in intensity of characteristic catechol peaks are accompanied by the appearance of new π^* resonances due to carbon in carboxyl (ca. 288.5 eV) and carbonyl (ca. 289.3 eV) groups, and the development of broad structure in the σ^* region characteristic of aliphatic carbon. Evolution of the C K-edge spectra is consistent with aromatic-ring cleavage and polymerization. These results further substantiate that the presence of catechol, O₂ (aq) causes both the oxidation of structural Ce³⁺ and the transformation of catechol to more complex organic molecules. Scanning Transmission X-Ray Microscopy measurements at the C K and Ce M_4,5 edges indicate three dominant organic species, varying in complexity and association with the inorganic phase. Untransformed catechol is loosely associated with CeO₂, whereas more complex organic molecules that exhibit lower aromaticity and stronger CO π^* resonances of carboxyl-C and carbonyl-C groups are only found in association with the grains. These results further serve as basis to postulate that, in the presence of O₂, CeO₂ can mediate the oxidative polymerization of catechol to form higher molecular weight polymers. The present work provides evidence for a pathway of biologically-induced, non-enzymatic oxidation of cerium and formation of small CeO₂ particles at room temperature. These findings may have implications for carbon cycling in natural and cerium-contaminated soils and aqueous environments.     

碳酸盐岩石成因类型的判别分析和白云鄂博“白云岩”的成因讨论

本文根据对世界上20多个国家和我国21个省碳酸盐岩石化学全分析数据的统计和换算结果,发现岩浆碳酸岩与沉积碳酸盐岩之间常量元素的一般含量无显著不同,但采用两组或逐步判别分析的方法,仍能将岩浆碳酸岩与沉积碳酸盐岩很好的区分开。判别效率可达90%以上。将这一方法应用到白云”鄂博矿区的“白云岩”和灰岩,90%以上的“白云岩”样品判为岩浆碳酸岩,灰岩的样品全部判为沉积碳酸盐岩,与它们的地质产状和地球化学特征一致。     

碳酸盐岩石成因类型的判别分析和白云鄂博“白云岩”的成因讨论

本文根据对世界上20多个国家和我国21个省碳酸盐岩石化学全分析数据的统计和换算结果,发现岩浆碳酸岩与沉积碳酸盐岩之间常量元素的一般含量无显著不同,但采用两组或逐步判别分析的方法,仍能将岩浆碳酸岩与沉积碳酸盐岩很好的区分开。判别效率可达90%以上。将这一方法应用到白云”鄂博矿区的“白云岩”和灰岩,90%以上的“白云岩”样品判为岩浆碳酸岩,灰岩的样品全部判为沉积碳酸盐岩,与它们的地质产状和地球化学特征一致。     

低渗透储层孔隙结构影响因素及其定量评价——以准噶尔盆地金龙2地区二叠系上乌尔禾组二段为例

利用薄片、扫描电镜、物性及压汞等资料,对金龙2地区三叠系上乌尔禾组二段(P_3w_2)低渗(含砾)砂岩储层孔隙结构及其影响因素进行了研究。结果表明:①乌二段属于低孔低渗储层,根据压汞曲线参数特征,将其孔隙结构划分为三类。②成岩作用控制了储层孔隙结构,定量计算结果表明,乌二段视压实率平均为53.54%、视胶结率平均为47.53%、视溶蚀率平均为13.84%、视微孔隙率平均为60.67%,表现为中等压实、中—强胶结、弱溶蚀、微孔发育等特征;压实作用、胶结作用、微孔隙发育主要控制储层孔隙结构的形成。③引入成岩综合指数来定量表征各种成岩作用的综合强度,其与储层孔隙结构参数(排驱压力、分选系数)以及储层品质因子(RQI)具有较好的统计相关关系,Ⅰ类储层成岩综合指数大于8%,Ⅱ类储层成岩综合指数为2%～8%,Ⅲ类储层成岩综合指数小于2%。因此,可以利用成岩综合指数定量评价储层孔隙结构。     

青海湖沉积物中的长链不饱和脂肪酮（长链烯酮）

在青海湖沉积物中检出了含有２～４个双键的长链（Ｃ₃₇－Ｃ₄₀）甲基和乙基脂肪酮。这是世界沉积于碱性环境和各种不同盐度条件下（耳海，淡水；青海湖，半咸水；尕海，咸水）的近代湖泊沉积物中的长链不饱和脂肪酮的首次详细报导。许多地球化学家广泛用这些化合物经过计算公式来估算海洋沉积物的古温度。如果对这些化合物估算海洋沉积物古温度的计算公式进行适当校正，那么也可用这些化合物来推知湖泊沉积物的古温度。     

中国东部主要成矿时代磷块岩的组成

本文研究了我国震旦、寒武纪磷块岩的矿石岩石学,主要矿石矿物为碳氟磷灰石,重要伴生矿物为伊利石,白云石和自生石英。磷块岩的化学组成有三个显著特点,一是品位随矿石类型的不同而异;二是随成矿域不同而异;三是随成矿时代不同而异。成矿背景,成矿环境、磷块岩相以及矿石组成等因素的差异是导致上述矿石组成变化的主要原因。     

The Grader layered intrusion (Havre-Saint-Pierre Anorthosite, Quebec) and genesis of nelsonite and other Fe–Ti–P ores

The Grader layered intrusion is part of the Havre-Saint-Pierre anorthosite in the Grenville Province (Quebec, Canada). This intrusion has a basin-like morphology and contains significant resources of Fe–Ti–P in ilmenite and apatite. Outcropping lithologies are massive oxide alternating with anorthosite layers, banded ilmenite–apatite–plagioclase rocks and layered oxide apatite (gabbro-)norites. Drill cores provide evidence for stratigraphic variations of mineral and whole rock compositions controlled by fractional crystallization with the successive appearance of liquidus phases: plagioclase and ilmenite followed by apatite, then orthopyroxene together with magnetite, and finally clinopyroxene. This atypical sequence of crystallization resulted in the formation of plagioclase–ilmenite–apatite cumulates or “nelsonites” in plagioclase-free layers. Fine-grained ferrodiorites that cross-cut the cumulates are shown to be in equilibrium with the noritic rocks. The high TiO₂ and P₂O₅ contents of these assumed liquids explains the early saturation of ilmenite and apatite before Fe–Mg silicates, thus the nelsonites represent cumulates rather than crystallized Fe–Ti–P-rich immiscible melts. The location of the most evolved mineral and whole rock compositions several tens of meters below the top of the intrusion, forming a sandwich horizon, is consistent with crystallization both from the base and top of the intrusion. The concentrations of V and Cr in ilmenite display a single fractionation path for the different cumulus assemblages and define the cotectic proportion of ilmenite to 21 wt.%. This corresponds to bulk cotectic cumulates with ca. 8 wt.% TiO₂, which is significantly lower than what is commonly observed in the explored portion of the Grader intrusion. The proposed mechanism of ilmenite-enrichment is the lateral removal of plagioclase due to its relative buoyancy in the dense ferrodiorite melt. This plagioclase has probably accumulated in other portions of the intrusion or has not been distinguished from the host anorthosite.