松辽盆地长岭断陷火山岩气藏的形成条件与分布规律

Changling fault depression is a compound fault depression complicated by interior fault, with faults in the west and overlap in the west. North of Changling fault depression show NNE strike while south is NW strike. Changling fault depression has undergone twochasmic stage which control the development and distribution of volcanic rock, one depression stage, later inversion and uplift stage which control the formation of natural gas reservoir, and basin atrophic stage. The main boundary faults and main faults in Changling fault depression control three volcanic cycles and the distribution of volcanic rock. Seismic reflection characteristic and logging response characteristic of volcanic rock in study area are obvious, and the distribution characteristic, volcanic cycle and active stage of volcanic rock can be revealed by seismic attribute, conventional logging data can distinguish clastic rock from volcanic rock or distinguish partial different types of volcanic rock. The reservoir property of rhyolite and volcanic tuff are the best. Favorable volcanic reservoir can be preserved in deep zone. Imaging logging and frequency decompostion technology of seismic data act as effective role in the study of reservoir physical property and gas-bearing properties of volcanic rock.. Hydrocarbon gas in study area is high and over mature coal type gas, the origin of CO2 is complex, it is either inorganic origin or organic origin, or mixing origin. Hydrocarbon gas is mainly originate from Shahezi formation and Yingcheng formation source rocks, CO2 is mainly mantle source gas. Hydrocarbon has the characteristics of continuous accumulation with two charging peak. The first peak represent liquid hydrocarbon accumulation time, The second peak stand for the accumulation time of gaseous hydrocarbon.CO2 accumulate approximately in Neocene. The source rock distribution range, volcanic rock and favorable reservoir facies, distribution characteristic of deep fault (gas source fault) and late inversion structure are the major factors to control gas reservoir formation and distribution. All the results show that these traps that consist of big inherited paleo uplift(paleo slope), stratigraphic overlap and thinning out, volcanic rock, are the most advantageous target zone.

新疆谢米斯台中段地区火山岩特征及其含矿性研究

Central Xiemisitai is located on the northwest edge of the Junggar Basin, bounded on the north by Sawuer Mountain, and southward Junggar Basin. Geotectonically, it is within the Chengjisi-Ximisitai-Santanghu island arc of Late Paleozoic, between Siberian and Junggar plates. The volcanics in this area mainly consist of acidic volcanic lava, rock assemblage of esite, dacite, and rhyolite, and the transitional phase is comparatively developed. Besides, Si2O of volcanics here covers a large range of 53.91-79.28t %, K2O of 1.71-6.94t%, and Na2O of 2.29-5.45t%, which is a set of metaluminous- peraluminous high K calc-alkaline to calc alkaline mid-acidic volcanic series. In addition, the volcanics are potassic to high-potassic assemblage, with slight shoshonite in. The REE curve of volcanics in central Xiemisitai is rightward and smooth, inclining to LREE enrichment, which reveals the characteristics of island-arc volcanics. Through the lithology changing from neutral to acidic, the negative anomaly of Eu is increasing. The volcanics here deplete HFSE such as Nb, Ti, P, etc., but relatively rich in LILE like Rb, K, Th, etc., possessing geochemistry characteristics of arc volcanics, which means that the lava source region is watery, under the meta-somatic contamination of subducted components. Moreover, high Ba and Sr show volcanics in epicontinental arc environment, and their contemporaneous granitoid rocks are also marked with the characteristics of volcanic arc granite. In central Xiemisitai, the volcanics zircon age of volcanic rhyolite is 422.5Ma± 1.9Ma, mid-late Silurian. Only one sample zircon has been measured for the present, not very convincing, so volcanics here might not come from Devonian volcanism. Consequently, further confirming the volcanic age will play a key role in the research on the beginning of volcanism in Xiemisitai area and even North Xinjiang. This area includes three copper mineralization types: a) from andesite fracture; b) from rhyolite fracture broken zone, with the copper mineralization distributed by veins along the fissure; and c) from quartz veins. The mineralization of earth surface in S24 ore spot is intensive, and the primary geochemistry reconnaissance anomaly is fairly good. According to display data, the maximum content of Cu is as high as 0.9% and as low as 0.05%. Also, ore-control fracture structure is having a considerable scale in the strike of fracture both horizontally and vertically downwards, and the result of the geophysics stratagem EH-4 system reveals obvious low-resistivity anomaly. As a result, we believe that the S24 plot is expected to be a volcanic copper deposit target area.

大兴安岭南段中生代火山-侵入杂岩带的双层叠置构造体制兼论滇中武定、易门碳酸质火山岩年代、来源及矿库与找矿研究

These are two parts included in this report. In the first part, the zonation of the complexes in its series, lithofacies, the depth of magma source and chambers is discussed in detailed for the first time based on the new data of petrol-chemistry, isotopes, tectono-magma activity of Mesozoic volcano-plutonic complexes in the southern Great Hinggan Mts. Then, the genetic model of the zonality, double overlapped layer system, is proposed. The main conclusions are presented as follows: The Mesozoic volcanic-plutonic complexes in the southern Great Hinggan were formed by four stages of magma activity on the base of the subduction system formed in late Paleozoic. The Mesozoic magmatic activity began in Meso-Jurassic Epoch, flourished in late Jurassic Epoch, and declined in early Cretaceous Epoch. The complexes consist dominantly of acidic rocks with substantial intermediate rocks and a few mefic ones include the series of calc alkaline, high potassium calc alkaline, shoshonite, and a few alkaline. Most of those rocks are characterized by high potassium. The volcano-plutonic complexes is characterized by zonality, and can be divided mainly into there zones. The west zone, located in northwestern side of gneiss zone in Great Xinggan mountains, are dominated of high potassium basalts and basaltic andesite. The middle zone lies on the southeast side of the Proterozoic gneiss zone, and its southeast margin is along Huangganliang, Wushijiazi, and Baitazi. It composed of dominatly calc-alkaline, high potassium calc-alkaline rocks, deep granite and extrusive rhyolite. The east zone, occurring along Kesheketong Qi-Balinyou Qi-Balinzuo Qi, is dominated of shoshonite. In generally, southeastward from the Proterozoic gneiss zone, the Mesozoic plutons show the zones-mica granitites zone, hornblende-mica granitite zone, mica-hornblende granitite zone; the volcanic rocks also display the zones of calc alkaline-high potassium calc alkaline and shoshonites. In the same space, the late Paleozoic plutons also display the same zonality, which zones are combined of binary granite, granodiorite, quartz diorite and diorite southeast wards from the gneiss. Meso-Jurassic Epoch granite plutons almost distribute in the middle zone on the whole. Whereas late Jurassic Epoch volcanic rocks distribute in the west and east zone. This distribution of the volcano-plutonic complexes reveals that the middle zone was uplifted more intensively then the other zones in Meso-Jurassic and late Jurassic Epoches. Whole rock Rb-Sr isochron ages of the high potassium calc-alkaline volcanic rocks in the west zone, the calc-alkaline and high potassium calc-alkaline granite the middle zone, shoshonite in the east zone are 136Ma, 175Ma and 154Ma, respectively. The alkaline rocks close to the shoshonite zone is 143Ma and 126Ma. The isochron ages are comparable well with the K-Ar ages of the rocks obtained previously by other researchers. The compositions of Sr ans Nd isotopes suggest that the source of Mesozoic volcanic-plutonic complexes in Great Hinggan Mts. is mostly Paleo-Asia oceanic volcanic-sedimentary rocks, which probably was mixed by antiquated gneiss. The tectonic setting for Mesozoic magmatism was subductive continental margin. But this it was not directly formed by present west Pacific subduction. It actully was the re-working of the Paleozoic subduction system( which was formed during the Paleo-Asia ocean shortening) controlled by west Pacific subduction. For this reason, Although Great Hinggan Mts. is far away from west Pacific subduction zone, its volcanic arc still occurred echoing to the volcanic activities of east China, it, but the variation trend of potassium content in volcano-plutonic complexes of Great Hinggan is just reverse to ones of west Pacific. The primitive magmas occurred in the southern Great Hinggan Mts. Include high-potassium calc-alkaline basalt, high potassium calc-alkaline rhyolite, high potassium rhyolite, non-Eu negative anomaly trachy-rhyolite et al. Therefore, all of primitive magmas are either mafic or acid, and most of intermediate rocks occurring in the area are the products of Mesozoic acid magma contaminated by the Paleozoic volcanic- sedimentary rocks. The depth of those primitive magma sources and chambers gradually increase from northwest to southeast. This suggests that Paleozoic subduction still controlled the Mesozoic magmatism. In summary, the lithosphere tectonic system of the southern Great Hinggan Mts. controlling Mesozoic magmatism is a double overlapped layer system developing from Paleozoic subduction system. For this reason, the depth of crust of the southern Great Hinggan Mts. is thicker than that of its two sides, and consequently it causes regional negative gravity abnormity. The second part of this report shows the prolongation of the research work carried on in my doctor's period. Author presents new data about Rb-Sr and Sm-Nd isotopic compositions and ages, geochamical features, genesis mineralogy and ore deposit geology of the volcanic rocks in Kunyang rift. On the base of the substantial work, author presents a prospect of copper bearing magnetite ore deposit. The most important conclusions are as follows: 1. It is proved that all of these carbonatites controlled by a ringing structure system in Wuding-Lufeng basin in the central Yunnan were formed in the Mesoproterozoic period. Two stages could be identified as follows: in the first stage, carbonatitic volcanic rocks, such as lavas(Sm-Nd, 1685Ma), basaltic porphyrite dykes(Sm-Nd, 1645Ma), pyroclastic rocks and volcaniclastic sedimentary rocks, formed in the outer ring; in the second stage, carbonatitic breccias and dykes(Rb-Sr, 1048 Ma) did in the middle ring. The metamorphic age of the carbonatitic lavas (Rb-Sr, 893 Ma) in the outer ring was determined. The magma of carbonatitic volcanic rocks derived mainly form enriched mantle whose basement is depleted mantle that had been metasomated by mantle fluid and contaminated by Archaean lower crust. Carbonatitic spheres were discovered in ore bearing layers in Lishi copper mining in Yimen recently, which formed in calcite carbonatitic magma extrusion. This discovery indicates that the formation of copper ore deposit genesis relates to carbonatitic volcanic activity. The iron and copper ore deposits occurring in carbonatitic volcanic- sedimentary rocks in Kunyang rift results from carbonatitic magmatism. Author calls this kind of ore deposits as subaqueous carbonatitic iron-copper deposit. The magnetic anomaly area in the north of Lishi copper mining in Yimen was a depression more lower than its circumference. Iron and copper ores occurrig on the margin of the magnetic anomaly are volcanic hydrothermal deposit. The magnetic body causing the magnetic anomaly must be magnetite ore. Because the anomaly area is wide, it can be sure that there is a large insidious ore deposit embedding there.