起伏地形上规则二度体复重磁场正演和直接反演

上接211页13　n个无限薄板叠加场反演13.1　复场展开以Mj代替2Mmj和2fMgj,以F(S)代替G′(S)和T(S),得复场F(S)= nj=1Mjσj-S=- nj=1MjS-σj。(13.1)展开上式,即F(S)=-1(S-σ1)(S-σ2)…(S-σn)×{M1(S-σ2)(S-σ3)…(S-σn)+M2(S-σ1)(S-σ3)…(S-σn)+…+Mn(S-σ1)(S-σ2)…(S-σn-1)}。(13.2)根据(9.2)、(9.9)式有(S-σ1)(S-σ2)…(S-σn)=-1F(S){Φ1+Φ2+…+Φn};Φ1=M1{Sn-1-x1(1)Sn-2+x2(1)Sn-3-　　　　…+(-1)n-1x(n-1)(1)},Φ2=M2{Sn-1-x1(2)Sn-2+x2(2)Sn-3-　　　　…+(-1)n-1x(n-1)(2)},Φn=Mn{Sn-1-x1(n)S…     

利用13X沸石分子筛净化含Pb~(2+)废水的实验研究

采用静态间歇法 ,实验研究了含Pb2 +废水的 pH值及吸附时间对 13X沸石分子筛吸附Pb2 +性能的影响 ,得出了最佳去除效果的优化条件为 :废水的 pH值接近中性 ,吸附时间 10min。通过吸附实验 ,确定了在Pb2 +初始浓度为 2 0mg/L的条件下 ,13X沸石对Pb2 +的吸附量为 2 1 4 2mg/g ,即每克沸石净化含Pb2 +废水的最大体积量约为 75 0mL。解析实验表明 ,加入沉淀剂 ,浓缩洗脱液中的Pb2 +即以PbS的形式生成沉淀 ,为回收金属铅提供了可能 ;13X沸石在循环使用 5次的条件下 ,对废水中Pb2 +的吸附率仍高达 98% ,重复使用性能良好。经处理后的净化水中Pb2 +的浓度小于 0 4mg/L ,显著低于国家废水排放标准GB8978 88的指标 ( 1 0mg/L)。 13X沸石对Pb2 +的主要吸附形式是离子交换和表面络合反应。     

复杂地层超长桩施工技术研究

福州市新都会花园广场,其施工场地工程地质条件复杂,设计灌注桩深度为60m左右。针对复杂地层中超长灌注桩桩施工的技术难点、应采用的技术措施、以及成孔工艺进行了分析与研究,总结了在复杂地层超长桩施工中采用气举反循环回转加冲击施工技术及桩底后压浆技术的运用成效。     

吉林省敦化地区晚三叠世碱性-亚碱性侵入杂岩体的地质特征及构造背景分析

吉林省敦化地区以碱厂沟、三岔子、青林子岩体为代表的碱性-偏碱性侵入杂岩体,主要由碱性辉长岩、角闪碱长正长岩、石英正长岩和角闪碱长花岗岩等组成,具复合环状深成杂岩之特征。辉长岩KAr同位素年龄为224Ma①,角闪碱长正长岩UPb同位素年龄为(223±1)Ma,表明岩体形成时代为晚三叠世。岩石化学、地球化学特征表明岩浆源于上地幔物质的部分融熔,但并非典型大陆裂谷性质的碱性岩,其形成标志着区域上南北向古亚洲构造域碰撞造山已结束,开始进入稳定大陆裂谷的发展阶段,并预示着北东向滨太平洋构造域的开始。     

关于赣西武功山地区构造问题的讨论

赣西武功山地区发育的穹窿状变形变质体的组成结构和成因机制与经典的变质核杂岩有相似之处，它们由内核和外壳组成，并具三层式结构特征。但其内核主要为花岗岩，核内和核外的地层几乎同时代，并无“古老变质核”，它的形成机制主要是岩浆底辟强力侵住引起地壳局部隆升和伸展滑覆。本文将赣西武功山地区的穹窿状变形变质体改称为“武功山岩浆核杂岩”。     

Partial melting and decompression of the Thor-Odin dome, Shuswap metamorphic core complex, Canadian Cordillera

The Thor-Odin dome region of the Shuswap metamorphic core complex, British Columbia, contains migmatitic rocks exhumed from the deep mid-crust of the Cordilleran orogen. Extensive partial melting occurred during decompression of the structurally deepest rocks, and this decompression path is particularly well recorded by mafic boudins of silica-undersaturated, aluminous rocks. These mafic boudins contain the high-temperature assemblages gedrite+cordierite+spinel+corundum+kyanite/sillimanite±sapphirine±högbomite and gedrite+cordierite+spinel+corundum+kyanite/sillimanite+garnet±staurolite (relict)±anorthite. The boudins are interlayered with migmatitic metapelitic gneiss and orthogneiss in this region.

The mineral assemblages and reaction textures in these rocks record decompression from the kyanite zone (P>8–10 kbar) to the sillimanite–cordierite zone (P<5 kbar) at T750 °C, with maximum recorded temperatures of 800 °C. Evidence for high-temperature decompression includes the partial replacement of garnet by cordierite, the partial to complete replacement of kyanite by corundum+cordierite+spinel (hercynite)±sapphirine±högbomite symplectite, and the replacement of some kyanite grains by sillimanite. Kyanite partially replaced by sillimanite, and sillimanite with coronas of cordierite±spinel are also observed in the associated metapelitic rocks.

Partial melt from the surrounding migmatitic gneisses has invaded the mafic boudins. Cordierite reaction rims occur where minerals in the boudins interacted with leucocratic melt. When combined with existing structural and geochronologic data from migmatites and leucogranites in the region, these petrologic constraints suggest that high-temperature decompression was coeval with partial melting in the Thor-Odin dome. These data are used to evaluate the relationship between partial melting of the mid-crust and localized exhumation of deep, hot rocks by extensional and diapiric processes.     

Mid–Cretaceous Episodic Magmatism and Tin Mineralization in Khingan-Okhotsk Volcano–Plutonic Belt, Far East Russia

Abstract: Age of magmatism and tin mineralization in the Khingan‐Okhotsk volcano–plutonic belt, including the Khingan, Badzhal and Komsomolsk tin fields, were reviewed in terms of tectonic history of the continental margin of East Asia. This belt consists mainly of felsic volcanic rocks and granitoids of the reduced type, being free of remarkable geomagnetic anomaly, in contrast with the northern Sikhote‐Alin volcano–plutonic belt dominated by oxidized‐type rocks and gold mineralization. The northern end of the Khingan‐Okhotsk belt near the Sea of Okhotsk, accompanied by positive geomagnetic anomalies, may have been overprinted by magmatism of the Sikhote‐Alin belt. Tin–associated magmatism in the Khingan‐Okhotsk belt extending over 400 km occurred episodically in a short period (9510 Ma) in the middle Cretaceous time, which is coeval with the accretion of the Kiselevka‐Manoma complex, the youngest accretionary wedge in the eastern margin of the Khingan‐Okhotsk accretionary terranes. The episodic magmatism is in contrast with the Cretaceous‐Paleogene long–lasted magmatism in Sikhote–Alin, indicating the two belts are essentially different arcs, rather than juxtaposed arcs derived from a single arc. The tin‐associated magmatism may have been caused by the subduction of a young and hot back‐arc basin, which is inferred from oceanic plate stratigraphy of the coeval accre‐tionary complex and its heavy mineral assemblage of immature volcanic arc provenance. The subduction of the young basin may have resulted in dominance of the reduced‐type felsic magmas due to incorporation of carbonaceous sediments within the accretionary complex near the trench. Subsequently, the back‐arc basin may have been closed by the oblique collision of the accretionary terranes in Sikhote–Alin, which was subjected to the Late Cretaceous to Paleogene magmatism related to another younger subduction system. These processes could have proceeded under transpressional tectonic regime due to oblique subduction of the paleo‐Pacific plates under Eurasian continent.     

提高旋流除砂器净化泥浆效果的试验研究

从分析单粒岩屑受力情况出发，研究了旋流除砂器的工作机理，指出了其中心部位出现的涡旋气柱将对泥浆净化效果产生显著影响。提出了可手动或自动调节结构参数的旋流除砂器改进设计，通过关于临界粒度、最小泥浆损耗量和预防排砂口堵塞的实验，验证了新型除砂器的净化效果非常了，尤其在西部缺水地区具有推广价值。     

华南在Rodinia古陆中位置的讨论——扬子地块西缘变质-岩浆杂岩证据及其与Seychelles地块的对比

沿扬子地块西缘出露的一系列变质杂岩的构造性质及形成时代是分析华南地块大地构造属性的关键。这些杂岩均被初始为低角度的正断层所围限 ,具有变质核杂岩的构造性质 ,其剥露时间在177Ma左右。目前 ,对这一区域几个代表性杂岩体进行的系统的岩石学和地球化学分析表明 ,这是一套主体为与俯冲板块有关的岛弧型岩浆杂岩 ,其形成时代从 72 6～ 86 4Ma ,时间跨度在 10 0Ma以上。证明这些岩石的形成与地幔柱作用无关。上述结果与最近在Madagascar东北缘、Seychelles岛及印度的Malani的一条类似的变质岩浆杂岩带的地球化学与地质年代学研究结果完全吻合 ,这个构造带被解释为一条沿Mozambique洋东缘的巨大的向东俯冲的安第斯型俯冲 岩浆岛弧带。据此我们推测在Rodinia古大陆中 ,华南地块位于印度板块东北缘 ,其南东则可能与澳大利亚相接。