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1.
滇西高原第四纪以来的隆升和剥蚀 总被引：9，自引：2，他引：7
由滇西高原内古夷平面的抬高、外流水系的河流阶地、高原外营歌海盆地和琼东南盆地的沉积响应,共同揭示滇西高原第四纪以来的快速隆升和剥蚀历史。第四纪以来滇西高原区域性抬升了610～700余米、被剥蚀了1095～1600m,其平均剥蚀速率为0．68～0．94mm／a。根据河流阶地计算出第四纪以来各时段的隆升速率;隆升在0．386～0．296Ma达到峰期,隆升速率为2．24～2．SOmm／a;1．6～0.647Ma隆升速率最缓慢为0．68～0．94mm／a。滇西高原第四纪以来的隆升量和隆升峰期与同期的青藏高原具有相似性,但隆升速率明显低于东喜马拉雅构造结的隆升速率。 相似文献
2.
麦哲伦海山区MD、ME、MF海山富钴结壳特征 总被引：10，自引：0，他引：10
麦哲化海山区MD、ME、MF海山具有三层构造的结壳特征，研究表明，结壳可分为上部较致密层、中部疏松层、下部致密层。致密层构造单一，含很少脉石矿物；疏松层构造杂乱，含有大量脉石矿物；较致密层介于两者之间，壳层矿物有锰相矿物（主要为水羟锰矿）、铁相矿物和次要矿物（粘土矿物、钙十字沸石、石英、方解石、磷灰石等）。不同壳层地球化学特征具有明显差异性，Ce异常表明在结壳从下层到上层的生长过程中，环境的氧化性逐渐减弱，结壳^10Be测年结果表明，疏松层的生长速率最大，其次为致密层，较致密层的生长速率最小。推测区的最老的结壳的生长年代为中新世晚期，在4Ma以前，区内水动力条件很弱，氧化性较强；4－3．1MaBP水动力条件较强，氧化性较弱；2．6MaBP以来，水动力条件为强－弱波动期，氧化性较弱。 相似文献
3.
4.
A detailed study of a nodule from the Somali Basin dated by 230Thexcess was correlated with the paleoceanographic events recorded in Site 236 (Leg 24) Deep Sea Drilling Project (DSDP) cores. Tentative indications are that the phase of nodule accretion starting with the development of pillar structure at a depth of 20 mm in the nodule around 13 Ma coincides with increased Antarctic Bottom Water (AABW) flow and an elevated calciumcarbonate compensation depth (CCD).
The Late Miocene lowering of the CCD is represented by the mottled zones between 8 and 18 mm in the nodule is characterised by an abundant silicate component (>20%) of aeolian origin. The Miocene/Pliocene boundary (5 Ma) occurs at a depth of about 8 mm and is represented by the development of pillar structure and a minimum of aeolian dust (10.3%).
The increased biological productivity of the Somali surface water since the Middle Miocene is demonstrated by the increasing Corg content of the nodule (from 0.11 to 0.19%) towards its surface. 相似文献
5.
太平洋中部柱状沉积物中的自生矿物 总被引：2，自引：0，他引：2
卢效珍 《海洋地质与第四纪地质》1992,12(1):67-72
根据《海洋四号》861—881航次获得的岩心资料,通过对沉积物类型的观察,对其中的几种自生矿物钙十字沸石、蒙脱石、重晶石、微结核、非晶质SiO_2等矿物的成因和与沉积物类型的相关性进行了探讨。 相似文献
6.
Three wells, all offshore, in southern Alaska studied using apatite fission track dating make a transect southward from Lower Cook Inlet to the Kodiak Shelf and include ARCO Lower Cook Inlet COST #1 well (LCI well), Chevron OCS-0248 #1A well (Shelikof Strait), and Kodiak COST KSSD #1 OCS 77-1 well (Stevenson Basin, Kodiak). The ages of deep partially annealed samples from Lower Cook Inlet well suggest that the region cooled between ~100 and 75 Ma and or sometime after. Two scenarios are presented: (1) maximum heating before cooling in Late Creta ceous times and (2) maximum heating before cooling during mid-Tertiary times. Which is better is uncertain from the thermal and age data alone, but mid-Tertiary or later uplift, erosion, and cooling is preferred because data from Shelikof well suggests that the mid-Cretaceous unconformity was minor relative to the mid-Tertiary unconformity. Finally, because of the ~12 C warmer past than present bottom-hole temperature, the base of the LCI well is now ~500 m shallower than during maximum, burial (12 C/24 C/km geothermal gradient). Single-grain apatite fission track ages (20-25 Ma) from deep in the Shelikof well approach the age of the overlying mid-Tertiary (Miocene; ~23 Ma) unconform ity, suggesting significant and rapid exhumation. This suggests that strongly annealed, once deeply buried strata were uplifted and cooled quickly prior to onlap of the unconformity. The Miocene unconformity, therefore, is interpreted to be the major unconformity in the Shelikof well section. In this scenario the section was buried deepest, and was therefore hottest, until the onset of mid-Tertiary erosion. Approximately 665 m of late Tertiary and Quaternary strata have since been deposited in Shelikof Strait and have reburied the Shelikof section to within ~536 m of its original maximum burial depth. Including modern water depth, the Shelikof well section has experienced ~1 km of burial+submergence since ~25 Ma (832 m section+166 m water=998 m). It follows that the depth to the base of the well is now ~290 m shallower than it would have been during maximum burial. Single-grain apatite fission track ages deep in the Kodiak KSSD1 well are as young as 20-25 Ma and approach the age of overlap of a mid-Miocene regional unconformity (<23 Ma). The deepest Eocene samples were exhumed to within 574 m of the Miocene unconformity surface during Miocene time and were reburied by ~1.7 km of late Tertiary strata. The total section before exhumation was ~5 km; this suggests that Oligocene-age deposits may have existed in the Stevenson Basin. Together with the known Eocene strata, such deposits were exhumed during ~4.4 km of uplift and erosion during a short interval culminating in early to middle Miocene times (>25-23 Ma). Unique and anomalous apatite compositions (high F-, low Cl-, moderate OH-) from the Eocene section could provide a chemical tracer for determining their sediment source along the northeast Pacific rim prior to translation and accretion. 相似文献
7.
全球三大洋海山钴结壳资源量估算 总被引：8，自引：0，他引：8
钴结壳具有Co、Ni、Cu和Mn及其他金属的潜在矿产资源和储存在结壳层中古环境信息的双重意义。与深海多金属结核和热液硫化物矿床相比,具有较高Co、Ni和Pt含量的海山钴结壳有可能成为商业勘探的潜在目标。为合理地估算出全球三大洋海山钴结壳资源量,基于我国西太平洋海山钴结壳拖网采样调查资料和对太平洋海山钴结壳资源分布规律和钴结壳矿区圈定参数指标的深入研究,按海山不同高度、不同洋壳年龄赋予不同结壳厚度,进而计算出全球三大洋海山钴结壳分布面积为3 039 452.14km2和干结壳资源量为(1 081.166 1~2 162.332 2)×108 t。太平洋海山钴结壳分布面积为2 123 087.12km2和干结壳资源量为(513.244~1 026.488)×108 t,大西洋海山钴结壳分布面积为512 509.74km2和干结壳资源量为(116.503 2~233.006 4)×108 t,印度洋海山钴结壳分布面积为403 855.28km2和干结壳资源量为(81.484 9~162.969 8)×108 t。三大洋海山钴结壳的Mn、Co、Ni和Cu金属量分别为(138.848 0~277.696 0)×108 t,(3.967 6~7.935 2)×108 t、(2.793 6~5.587 2)×108 t和(0.825 1~1.650 2)×108 t。根据钴结壳的Co含量、Co通量和厚度相关分析,所赋予的钴结壳厚度占理论推测厚度的6.10%~12.20%,这与Ku等得出"钴结壳生长时间约占其整个生命史4%"的认识非常相近。三大洋海山钴结壳实测厚度与赋值厚度对比分析表明,太平洋海山钴结壳赋值厚度平均值为1.87cm,实测厚度平均值为1.77cm,相对误差为5.35%,大西洋和印度洋相对误差分别为18.18%和23.23%。研究数据表明按海山高度和洋壳年龄所赋的钴结壳厚度基本合理,估算出的钴结壳资源量基本可靠。本文首次估算出三大洋海山钴结壳资源量,为整个海盆和三大洋海山钴结壳资源量估算提供了新方法。 相似文献
8.
加速器质谱法测定深海锰结核样品中的^10Be 总被引：1，自引：0，他引：1
本文研究深海锰结核中＾１０Ｂｅ的加速器质谱法分析。提出了ＮａＯＨ和ＥＤＴＡ分离纯化－ＢｅＯ制样－加速器质谱法测量＾１０ＢｅＯ制样－加速器质谱法测量＾１０Ｂｅ的分析程序。研究结果表明,该法回收率较高,分离效果较好,按该法制备的ｅＯ靶能较好地满足加速器质谱法对测量＾１０Ｂｅ的要求。利用该法测得北太平洋两个锰结核的生长速率分别为２．７ｍｍ／Ｍａ和１．５ｍｍ／Ｍａ。这些结果与其他研究者所测数据相比,非常一 相似文献
9.
《Deep Sea Research Part I: Oceanographic Research Papers》2001,48(11):2529-2540
Polymetallic nodules (PN) collected from the north-east Pacific Clarion-Clipperton region were investigated with a 192Ir dual-energy gamma-ray computer tomograph. Tomographic images depicting density and effective atomic number distribution of the same section were obtained. These images present a linear response for a broad range of sample densities (0.97–6.22 g/cm3), and likewise effective atomic numbers (5.48–29). Sixty-five successive digital sections, each with a thickness of 0.8 mm, reveal the 3-D density as well as the effective atomic number distribution function over the entire nodule volume, allowing one to obtain virtual sections across any desired plane. The tomograms show many details of internal structure of the investigated nodule such as an old nucleus, fissure networks or layer structures. The total concentration of iron and manganese determined by this method was equal to 19.4±1.7%. Gamma-ray computer tomography considerably extends the quantitative analysis capability of classic X-ray computer tomography. 相似文献
10.
Xiangwen Ren G. P. Glasby Jihua Liu Xuefa Shi Jingwu Yin 《Marine Geophysical Researches》2007,28(2):165-182
The internal structure and composition of a 37-mm-thick Co-rich Mn crust from the Lamont Guyot in the Marcus-Wake Seamount
cluster have been studied in detail by means of electron-probe microanalysis (EPMA). 184 point analyses for 16 elements were
carried out at an average spacing of 0.20 mm and each point was dated using the Co-geochronometer method. Two types of variation
in composition were observed in the crust: long-term trends and short-term erratic variations. The long-term trends were identified
using the fifth order polynomial. Mn and Ni were shown to increase in concentration from 23.3 Ma to a maximum at about 20 Ma
and then decline steadily to the Present, whereas Fe, P and Si showed the opposite trend. By contrast, Co displayed a double
humped pattern with maxima at about 19 Ma and 3.5 Ma and minima at 23.3 Ma, about 11 Ma and at Present. The long-term trends
in element concentrations in the crust lead us to suggest that much of the Fe in western Pacific Ocean ferromanganese crusts
is aeolian in origin and derived from the deserts of central Asia. Cooling of the Asian mainland at about 20 Ma led to an
increase in the flux of Fe to the oceans. This was supplemented by an additional input of Fe into the crusts as a consequence
of the dissolution of biogenic CaCO3 tests at 4.5−10.5 Ma. For the short-term erratic variations, three periods of 0.61, 0.96 and 1.65 m.y. were identified by
spectral analysis. The second harmonics of these periods are 1.22, 1.92 and 3.30 m.y., which may correspond to the highest-order
periods for eccentricity of 1.31, 2.04 and 3.47 m.y. This suggests the possibility that the high-frequency oscillations of
the time series data are linked to climatic changes controlled by the highest-order periods of the Milankovitch cycles. 相似文献
11.
A sampling expedition has shown that largely hydrogenetic marine ferromanganese deposits occur in the Christmas Island region south of Java (~10°S), as small nodules on seamount slopes and abyssal plains (red clay), and as thick crusts on volcanic ridges and seamounts. Vernadite is dominant, with birnessite, jacobsite and todorokite common. Nodules were recovered in 25% of free-fall grab stations in water 4600-5900 m deep, and are not abundant where present. The nodules average 9.6% Fe, 19.7% Mn, 0.51% Ni, 0.49% Cu, and 0.12% Co. Crusts are common in water 1450-3700 m deep, with average deposition rates of 1-1.5 mm / m.y. The crusts average 13.9% Fe, 16.2% Mn, 0.35% Ni, 0.11% Cu, and 0.44% Co. Cobalt grades are higher (~0.8%) in shallower water ( < 2500 m), so future exploration should concentrate on depths of 500-1500 m near the oxygen minimum zone. 相似文献
12.
稀土元素在成岩型海洋铁锰结核中的富集特征及机制 总被引：2，自引：0，他引：2
借助相分析中的偏提取方法对取自东太平洋深海平原上的成岩型铁锰结核进行了选择性提取实验以研究稀土元素在其中各矿物或氧化物相中的分布模式以及铁氧化物和锰氧化物对稀土元素的吸附机制.结果显示,尽管1 nm-水锰矿相对无定形铁的氧化物/氢氧化物而言是成岩型结核中的优势矿物,但是稀土元素主要富集在无定形铁的氧化物/氢氧化物中.虽然稀土元素在海水中主要是以碳酸盐络合物的形式存在,但是无定形铁的氧化物/氢氧化物则是从海水中获得自由稀土元素离子来络合,而1 nm-水锰矿则直接吸附稀土元素的碳酸盐络合物.因此,无定形铁的氧化物/氢氧化物对稀土元素来说具有比1 nm-水锰矿更强的络合能力.成岩型结核的Ce负异常是由于成岩型结核形成于缺氧微环境中,该环境不能把可溶性的Ce~(3+)氧化成不溶性的Ce~(4+)发生沉淀. 相似文献
13.
本文对采自东太平洋CC区的2块不同类型的铁锰结核及中太平洋麦哲伦海山的1块富Co结壳,采用XRD和ICP-MS(AES)等分析研究方法,进行了矿物地球化学的比较研究。结果表明:铁锰结核主要由水羟锰矿及钡镁锰矿组成,富Co结壳主要以水羟锰矿为主。与2块铁锰结核相比,富Co结壳总体上Cu、Al、Na含量较低而Co含量较高;两块不同类型的结核相比较,水成型铁锰结核的P、Ti含量较高,而成岩型铁锰结核的Cu、Ni含量较高。3块样品的稀土元素含量均较高,为(521.8~1 424.15)×10-6。REE分布型式总体呈平缓型,(La/Yb)N为0.72~1.01,并具程度不同的Ce、Eu正异常。经估算,富Co结壳的生长速率为1.92~4.24mm/Ma,水成型铁锰结核的生长速率为1.31~14.29 mm/Ma,成岩型铁锰结核的生长速率为11.24~76.32mm/Ma。并根据铁锰结核的化学成分变化推测了其生长环境的变化。 相似文献
14.
15.
Nuclei of ferromanganese nodules from the Central Indian Ocean Basin show the presence of abundant plagioclase feldspars
(1–3 mm diameter). They are identified as calcic plagioclase (peak at 3.20 Å). Plagioclase chemical composition (CaO 6.4–20.5%)
shows a range of An 44–90%. The mineral chemistry, together with the bulk composition of the host nuclei, indicate that they
are of basaltic composition. A possible source could be the numerous seamounts in this basinal area.
Received: 4 October 1996 / Revision received: 28 April 1997 相似文献
16.
Chemical and X-ray analyses were performed on the fifteen manganese nodules collected from the Pacific Ocean floor. The results
were discussed compared with the previous data on the manganese nodules. Minerals were found to be todorokite, δ-MnO2 and other silicates, montmorillonite, illite, phillipsite and α-SiO2. Average composition shows that copper is concentrated on the deep sea nodules more than the shallow ones, and that the todorokite
rich nodules contain more copper and nickel than the δ-MnO2 rich ones. The analyses of fresh water iron-manganese precipitates by bacterial activity suggest that biological process
is one of the important factors on the genesis of the sedimentary iron-manganese deposits, including the manganese nodule.
The Institute of Physical and Chemical Research 相似文献
17.
In the present paper, iodine(I), iron(Fe), manganese(Mn), cobalt(Co), phosphorus(P) and calcium(Ca)contents in three ferromanganese crusts from the Pacific Ocean are measured by spectrophotometric method and inductively coupled plasma atomic emission spectrometers(ICP-AES) to investigate the contents and distribution of iodine in ferromanganese crusts. The results show that iodine contents in three crusts vary between 27.1 and 836 mg/kg, with an average of 172 mg/kg, and the profile of iodine in the three crusts all exhibits a two-stage distribution zone: a young non-phosphatized zone and an old phosphatized zone that is rich in I, P and Ca. The iodine content ratios of old to young zone in MP5D44, CXD62–1 and CXD08–1 are 2.3, 3.4 and 13.7, respectively.The boundary depths of two-stage zone in MP5D44, CXD62–1 and CXD08–1 locate at 4.0 cm, 2.5 cm and 3.75 cm,respectively, and the time of iodine mutation in three crusts ranges from 17–37 Ma derived from 129 I dating and Co empirical formula, which is consistent with the times of Cenozoic phosphatization events. The present study shows that the intensity of phosphatization is the main responsible for the distribution pattern of iodine in the crusts on the basis of the correlation analysis. Consequently, iodine is a sensitive indicator for phosphatization. 相似文献
18.
JI Lihong LIU Guangshan CHEN Zhigang HUANG Yipu XING N JIANG Shan HE Ming 《海洋学报(英文版)》2015,34(10):31-35
In the present study,the analytical method for 129iodine(129I) in ferromanganese crusts is developed and129iodine/127iodine(129I/127I) ratio in ferromanganese crusts is measured by the accelerator mass spectrometry(AMS).The developed method is applied to analyze 129I/127 I ratio in two ferromanganese crusts MP5D44 and CXD08-1 collected from the Mid-Pacific Ocean.The results show that 129I/127 I ratio in MP5D44 and CXD08-1crusts varies from 7×10–14 to 1.27×10–12,with the lowest value falling on the detection limit level of AMS reported by previous literatures.For the depth distribution of 129I/127 I,it is found that both MP5D44 and CXD08-1 crusts have two growth generations,and the 129I/127 I profiles in two generations all displayed an approximate exponential decay.According to the 129I/127 I ratio,the generate age of bottom layer of MP5D44 and CXD08-1 was estimated to be 54.77 and 69.69 Ma,respectively. 相似文献
19.
Ferromanganese concretions within the Polish Exclusive Economic Zone (EEZ) are found mainly in the depth range 60–70 m on the thresholds between the Bomholm Basin and Slupsk Furrow and between the Gotland and Gdansk Basins. They also occur on elevations of the seafloor within the Bomholm Basin, on the southern slopes of Slupsk Furrow, and on the lower southwestern slopes of the Gotland Basin. They occur mainly as surface deposits on very thin (<0.2 m), poorly sorted lag deposits. The concretions are predominantly discoidal and are formed around a single nucleus of sandstone or erratic rock of variable size. The ferromanganese oxides display internal layering with alternate layers of almost black manganese oxides and buff iron axyhydroxides. The concretions consist mainly of todorokite and quartz, with lesser amounts of feldspar, kaolinite, and montmorillonite. They are characterized by relatively high Fe/Mn ratios (0.9–3.5) and high contents of detrital elements (Ti, Na, K, Ca, and Mg) but low contents of the transition elements (Cu, Zn, Pb, Cr, Co, and Ni). The deposits are associated with the very dynamic environment near the halocline, where internal waves erode the sediment and create conditions of sediment nondeposition favorable for the formation of the concretions. A number of factors contribute to the high abundance of ferromanganese concretions in the Baltic Sea. One is the high input of iron and manganese by the rivers draining into it This is a consequence of the widespread occurrence of bogs and swamps in the catchment area of the Baltic Sea, which results in the river waters having high humic acid contents and low pH. Another major factor is the buildup of dissolved iron and manganese in the anoxic basins of the Baltic Sea during periods of stagnation. These waters are flushed during major inflow events, when oxygenated water from the North Sea displaces the stagnant waters of the anoxic basins. Iron and manganese in these waters are then transported laterally and deposited in the surface of ferromanganese concretions on topographic highs. We believe that the iron is deposited rapidly after such events but that the manganese is deposited over a much longer time period, thus accounting for the layering in the concretions. The rate of deposition of these elements is essentially controlled by the input of oxygen in the waters of the North Sea. These periods of major inflows are grouped but significant events, for concretions occur on average about 11 times per century. We therefore estimate that the concretions have grown much more slowly than previously thought (about 0.013–0.018 mm/yr), and that a concretion 20 mm in diameter would have an age of about 500–800 years. Higher concentrations of heavy metals have been recorded in the outer layers of the concretions, and it is possible that these can serve as indicators of heavy‐metal pollution in the Baltic Sea. The concretions range from sporadic to intermediate abundance. As such, they have no economic potential. 相似文献
20.
The formation of ferromanganese concretions on continental shelves is a widespread recent biogeochemical process, which is particularly intense in the Baltic Sea. The proposed new technique for dating ferromanganese concretions is based on the equilibrium 210Pb, which is produced immediately within them due to the decay of 226Ra, which is intensely sorbed by concretions from the seawater. This method is principally different from the traditional dating of bottom sediments using nonequilibrium 210Pb, which represents a decay product of atmospheric Ra. A mathematical tool for the calculation of the concretion ages is proposed. The latter is used for calculating the ages and growth rates of ferromanganese concretions belonging to two morphological varieties. The age and average growth rates of spheroidal concretions are estimated to be 670–850 years and 0.014 mm/year, respectively. The central part of a pancake-shaped concretion is dated back to 2500–3800 years, and its calculated respective horizontal and vertical growth rates are approximately 0.028 and 0.004 mm/year. 相似文献