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1.
浙江长兴更新世红土中的分子化石及其古环境意义 总被引：9，自引：2，他引：9
利用GC／MS从浙江长江更新世红土中检测出种类繁多但含量甚微的分子化石，主要包括正构烷烃、长链三环萜、五环三萜、一元正脂肪酸、正脂肪醇、正烷基－2－酮等系列。红土中的这些分子化石，特别是正构烷烃的特征表明本区的红土是在多水的环境下形成的，并且其上发育了以草本植物为主的高等植被。三环萜烷与三萜烷比值（C23／C30）随地层的变化与红土网纹化程度密切相关，可能具有潜在的古气候指示意义。 相似文献
2.
《海洋湖沼通报》2017,(2)
本文通过2012年5月份和9月份两次采样,研究了碣石湾表层海水油指纹特征参数的大小和差异。结果表明:5月份碣石湾表层海水正构烷烃呈单峰分布,主峰碳为n-C16,9月份海域海水正构烷烃呈双峰型,前峰明显高于后峰,5月份表层海水受到油类影响,9月份表层海水同时受到油类污染和陆生高等植物的影响。在碣石湾表层海水的甾烷和萜烷中,5月和9月份碣石湾表层海水17α(H),21β(H)-藿烷(C30)为主要成分,其次为17α(H),21β(H)-30-降藿烷(C29);胆甾烷(C27甾烷)和乙基胆甾烷(C29甾烷)的ααα占优,甲基胆甾烷(C28甾烷)含量相对较低。 相似文献
3.
《海洋地质与第四纪地质》2010,(3)
研究了墨西哥湾水深约2 200 m的下陆坡Alaminos Canyon 645区块(AC 645区)冷泉碳酸盐岩中含量较高的烷基环戊烷、烷基环己烷、直链烷基苯及苯基烷烃化合物的组成和分布特征。烷基环戊烷和烷基环己烷以低碳数烃占绝对优势,主峰碳分别为C14和C15,目前发现的烷基环己烷主要来源于嗜热嗜酸的细菌或藻类直链脂肪酸经环化作用的产物。烷基苯碳数分布范围为C13—C23,以C13—C20的低碳数烷基苯为主,主峰碳为C16,具有明显偶碳优势,很可能来源于冷泉渗漏环境中的喜盐细菌。 相似文献
4.
本文对南海深海和冲绳海槽二个柱状样进行了正构烷烃、甾烷和萜烷生物标记化合物分布特征的研究。由于它们所处的沉积环境和生源母质上的差异,反映在正构烷烃的CPI值、C_(17)和C_(18)的含量、轻重烃比值、化合物构型的转化、有机质的成熟度和17α(H)-22,29,30-三降藿烷与18α(H)-22,29,30-三降新藿烷的比值等地球化学参数上的差别。冲绳海槽沉积物的多源性决定了其有机组分的特殊性,如生物来源的C_(17)和C_(18)量占有优势,有机碳含量(1.0—1.3％)高于南海样(0.3—1.0％),重排甾烷量少,生物构型的ββ藿烷已转变成地质构型的αβ藿烷和βα型莫烷化合物。 相似文献
5.
南黄海海底沉积物饱和烃类地球化学特征及其指示意义 总被引：1，自引：0，他引：1
南黄海海底沉积物正构烷烃分布具有3种类型：第1类以低碳数占优势，主要来源于以浮游生物和细菌为主的有机质；第2类以高碳数占优势，主要来源于以陆源高等植物蜡供应为主的有机质；第3类显示双峰特征，陆源高等植物蜡与浮游生物和细菌均具有一定的贡献。Pr／Ph比值的范围为0．174～0．753之间，显示植烷优势，代表还原环境，其中，一些Pr／Ph比值相对较高的站位也一定程度上反映了存在陆生高等植物的贡献。藿烷和甾烷组成指示，有机质主要来源于陆地植物，沉积物来源区所处的环境为大陆、港湾及河湾及其过渡环境。一些站位样品的藿烷和甾烷等相关参数显示，南黄海海底沉积物具有较高的成熟度，明显偏离现代生物所应有的藿烷和甾烷等相关参数范围，表明有石油源有机质混入的迹象，混入的石油源烃可能来自人类活动和海底油气渗漏。 相似文献
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7.
以曹妃甸邻近海域为研究区,利用生物标志化合物地球化学参数分析了表层沉积物中石油烃类的主要组成和分布特征,探讨了石油烃污染物的来源。结果表明,曹妃甸邻近海域表层沉积物中正构烷烃为混源,且陆源贡献小于海洋源。地质构型藿烷、甾烷在甾萜类化合物中为优势组分,且萜甾烷参数显示了有机质成熟度较高。饱和烃的多种地球化学参数显示了该区域表层沉积物可能受到成熟度较高的石油烃输入及其后期微生物降解的影响。该研究将为曹妃甸近岸沉积物输移研究提供基础资料,进而为曹妃甸围填海工程的科学决策提供相关科学数据。 相似文献
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南黄海北部表层沉积物中生物标志物的组成特征及其地球化学意义 总被引：1，自引：0，他引：1
通过对南黄海北部14个站位的19个表层沉积物样品进行了粒度、有机碳、GC-FID和GC-MS-MS测定,探讨沉积物有机质中生物标志物组成特征及地球化学意义。研究区表明,沉积物有机碳含量较高,正构烷烃呈双峰分布,具有明显奇偶优势、平均L/H为0.36,说明沉积物中陆源高等植物贡献占优,分析对比表明其沉积物可能主要来自古黄河输入。类异戊二烯烃Pr/Ph均值0.46,表明有机质沉积于强还原环境;Pr/C17和Ph/C18值均小于1,并且随深度有减小的趋势,反映了研究区微生物的降解作用。甾类化合物C29豆甾烷>C（?）胆甾烷>C28麦角甾烷,说明萜类化合物和甾类化合物主要为陆相输入。较高OEP值、高丰度的藿烯和莫烷及甾烷S构型含量均反映了现代沉积物中有机质未熟-低熟特征,但由于原始母质影响和微生物发育,Ts/Tm和C31αβS/（S+R）、C32αβS/（S+R）、C33αβS/（S+R）和C29αββ/（ααα+αββ）值较高。 相似文献
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Organic carbon accumulation and sulfate reduction rates in slope and basin sediments of the Ulleung Basin,East/Japan Sea 总被引：1，自引：0，他引：1
This study investigated the organic carbon accumulation rates (OCARs) and sulfate reduction rates (SRRs) in slope and basin
sediments of the Ulleung Basin, East/Japan Sea. These sediments have high organic contents at depths greater than 2,000 m;
this is rare for deep-sea sediments, except for those of the Black Sea and Chilean upwelling regions. The mean organic carbon
to total nitrogen molar ratio was estimated to be 6.98 in the Ulleung Basin sediments, indicating that the organic matter
is predominantly of marine origin. Strong organic carbon enrichment in the Ulleung Basin appears to result from high export
production, and low dilution by inputs of terrestrial materials and calcium carbonate. Apparent sedimentation rates, calculated
primarily from excess 210Pb distribution below the zone of sediment mixing, varied from 0.033 to 0.116 cm year−1, agreeing well with previous results for the basin. OCARs fluctuated strongly in the range of 2.06–12.5 g C m−2 year−1, these rates being four times higher at the slope sites than at the basin sites. Within the top 15 cm of the sediment, the
integrated SRRs ranged from 0.72 to 1.89 mmol m−2 day−1, with rates approximately twice as high in the slope areas as in the basin areas. SRR values were consistently higher in
areas of high sedimentation and of high organic carbon accumulation, correlating well with apparent sedimentation rates and
OCARs. The sulfate reduction rates recorded in the basin and slope sediments of the Ulleung Basin are higher than those reported
for other parts of the world, with the exception of the Peruvian and Chilean upwelling regions. This is consistent with the
high organic carbon contents of surface sediments of the Ulleung Basin, suggesting enhanced organic matter fluxes. 相似文献
13.
Benthic foraminiferal and sediment biogeochemical data (total organic carbon, calcium carbonate and biogenic opal contents)
in two cores (1265 and 1312 m water depths) from the southeastern Sakhalin slope and one core (839 m water depth) from the
southwestern Kamchatka slope were investigated to reconstruct variations of the oxygen minimum zone during the last 50 ka
in the Okhotsk Sea. The oxygen minimum zone was less pronounced during cooling in the MIS 2 that is suggested to be caused
by a maximal expansion of sea ice cover, decrease of marine productivity and increase of production of the oxygenated Okhotsk
Sea Intermediate Water (OSIW). A two-step-like strengthening of oxygen minimum zone during the warmings in the Termination
1a and 1b was linked to (1) enhanced oxygen consumption due to degradation of large amount of organic matter in the water
column and bottom sediments, originated from increased marine productivity and supply of terrigenous material from the submerged
northern shelves; (2) sea ice cover retreat and reduction of OSIW production; (3) freely inflow of the oxygen-depleted intermediate
water mass from the North Pacific. 相似文献
14.
南海北部琼东南盆地海底存在着巨型麻坑, 现有研究多认为其形成主要与海底流体渗漏有关。目前对琼东南盆地深海沉积物地球化学特征及麻坑区的生物地球化学过程等尚不清楚。文章选取南海北部琼东南盆地C14、C19两个站位岩心样品, 进行了总硫(TS)、总碳(TC)、总有机碳(TOC)、铬还原性硫化物(CRS)及其δ34SCRS值测试, 并结合总氮/总碳(TN/TOC)比值和已发表的孔隙水中SO42-浓度等进行了地球化学特征分析。研究表明: C14站位以3.91m bsf (below seafloor)为界, 上下分别存在有机质参与的硫酸盐还原反应(OSR)和甲烷厌氧氧化作用(AOM)驱动的硫酸盐还原反应(SR); 3.91m bsf以上的部位沉积物的TS、TC含量均低于3.91m bsf以下部位, 且沉积物孔隙水中SO42-浓度由3.91m bsf以上的缓慢凹型减少变成3.91m bsf以下的线性减少, 说明该处成为沉积物中地球化学特征分界的明显标志; 在3.91m bsf以下, 受到甲烷渗漏的影响。C19站位沉积物中TS与TC含量由浅到深逐渐增加, 但与TN/TOC比值变化呈现几乎相反趋势, 即整个岩心以OSR为主, 并呈现出有机质早期成岩阶段的沉积现象。C14和C19两个站位柱状沉积物的δ34SCRS值变化范围分别为-50.2‰~-46.9‰和-50.1‰~-42.0‰ (V-CDT标准), 均显示出了较为偏负的硫同位素值, 表明研究区主要的生物化学过程是在相对开放体系下硫酸盐还原作用的结果, 综合说明该研究区麻坑的甲烷流体已经喷发, 目前可能处于衰退期, 甚至已经不活跃, 该结果与前人的认识基本一致。 相似文献
15.
Organic matter in cobalt-rich crust(CRC) from the Marcus–Wake Seamounts of the western Pacific Ocean, Sample CM1D03, has been analyzed to understand the source, geochemistry and mineralization of organic matter, and the mineralization environment. Biomarkers, including n-alkanes, isoprenoids, terpanes and sterols, have been detected in various layers of the CRC sample, using gas chromatography(GC) and gas chromatography–mass spectrometry(GC–MS). The content of organic carbon(OC) and its stable isotope(δ13C), and the combined features of the biomarkers show that the mineralized organic matter in CM1D03 CRC was mainly derived from microorganisms and lower plankton(e.g., bacteria and algae, respectively) from marine surface water, with some terrestrial higher plant components. The ratio of chloroform bitumen "A": OC was high in the CRC, between 10.51 and 20.66, showing significant migration characteristics of n-alkanes. Four mineralization categories of organic matter were recognized based on GC chromatograms of n-alkane molecules:(1) primitive type(bacteria and algae), which is characterized by moderately mature of n-alkanes preserving the original characteristics of the organic matter from microorganisms and lower plankton;(2) microbial degradation type, which is characterized by low contents of n-alkanes and rising baseline in the chromatogram, with the "bulge" being the products of organic matter by biodegradation;(3) organic matter migration type, which is characterized by low carbon number of n-alkanes with n C18 as the main peak carbon, without odd even predominance, and low concentrations of isoprenoids and hydrocarbons with high carbon number; and(4) organic matter hydrothermal type, which is characterized by relatively low concentration of small molecular weight n-alkanes, pristane, and phytane, accompanied by higher concentration of n-alkanes with carbon number greater than n C18. This study shows that biomarkers can record controlling factors of mineralization and their variation. 相似文献
16.
Density, biomass and community structure of macrofauna were estimated together with several sediment characteristics at seven stations ranging from 208 m to 4460 m water depth along the OMEX transect in the Goban Spur area (NE Atlantic) during three seasons (October 1993, May 1994, and August 1995). Median grain size decreased with increasing water depth and showed no differences between the seasons. The percentages of organic carbon and total nitrogen were highest at mid-slope depths (1000 to 1500 m), and were significantly higher in August at the upper part of the slope to a depth of 1500 m. The C:N ratio in the surface layer amounted to 7 to 8 in May, 10 to 12 in August and 14 to 17 in October at all stations (except the deepest at 4460 m, where it was 11 in May and August), indicating arrival of fresh phytodetritus in May, and therefore seasonality in food input to the benthos. Densities of macrofauna decreased exponentially with increasing water depth. Significantly higher densities of macrofauna were found in May at the upper part of the slope to a depth of 1500 m. These differences were mainly due to high numbers of postlarvae of echinoids at the shallowest station and ophiuroids at the deeper stations. Biomass values also decreased with increasing water depth, but biomass was relatively high at the 1000 m station and low at 1500 m, due to relatively high and low mean weights of the individual macrofaunal specimens. No significant differences in biomass were found between the seasons. Respiration was high (15 to 20 mgC·m−2·d−1) in May at the upper part of the slope to a depth of 1000 m and low (1–3 mg C·m−2·d−1) at the deeper part. At the shallowest stations to a depth of 1000 m respiration was highest in May, at the mid-slope stations (1400–2200 m) it was highest in August, whereas the deepest stations (3600 to 4500 m) did not show any differences in respiration rates. In conclusion; seasonal variation in organic input is reflected in denstiy, community structure and activity of the macrofauna along the continental slope in the NE Atlantic. 相似文献
17.
Abstract A giant submarine slump, encompassing a 91‐km by 26‐km block, occurring on the continental slope offshore Iquique, Chile, was identified during a SeaMARC II survey. Utilizing SeaMARC II side‐scan imagery, bathymetry, and seismic reflection data, five morphostructural zones of the slump were identified: the fissured zone, scar zone, tensional depression, central block, and front zone. The fissured zone was developed on the crown of the slump; the scar zone is characterized by scars with the crescent‐shaped slip surfaces and throws ranging from 200 m to 50 m. The tensional depression zone is marked by an area voided by mass slumping, while the central block morphology was formed by uplift. The front zone is comprised of both compressional and tensional subzones. The compressional subzone is characterized by a relative topographic low, on the middle slope, whereas the extensional subzone is characterized by a convex pattern of alternated ridges and hollows, which may represent the debris of the slump on the lower slope. The formation of the slump was strongly influenced by the subduction of the Nazca plate beneath the Chile continental margin, which resulted in the subsidence of the continental slope with a resultant increase in the slope gradient and pore‐water pressure in the sedimentary layers. Slump formation was further facilitated by the development of a complex fault system associated with the subduction and by the triggering effect of earthquakes in the area. 相似文献
18.
Abstract Subbottom profiling (3.5 kHz) in the uppermost slope of the outer shelf of the northwestern Aegean Sea has shown downslope slumping and intense sediment deformation as well as a succession of microslumping within the Late Pleistocene delta sequences. Postdeposition bottom erosion by currents and the overconsolidated sediments (Cu/Po > 1) indicate the termination of deformations a long time ago. Deformation processes are estimated to have been active 18,000–10,000 B.P. Large‐scale active downslope deformations with clockwise sediment block rotation have affected the area as well. These longer‐period deformations are associated with regional neotectonics and older unconformities (i. e., Plio‐Pleistocene) as potential slide planes. Geotechnical properties reflect mainly textural variations and locally (within sapropelic layers) high organic matter content. Relatively high values of shear strength were measured (5–29 kPa) with intermediate sensitivities (2–5), whereas relatively low values of water content (33–81%) were found along the five selective sediment cores. Infinity slope stability analysis revealed that the slopes in the study area are most stable, although theoretical evaluations (Cu estimated from linear regression analysis) indicate relative instability for the potential glide plane at 20 m depth. The outer shelf is covered by compact relict sands, and their gentle and low‐angle (<0.2°) slopes are the most stable region of the investigated area. 相似文献
19.
为了解特殊地质体与天然气水合物成藏构造特征之间的关系,作者以冲绳海槽西侧陆坡和槽底为例,利用地震资料和地球化学方法对该地区上新世和第四纪沉积物厚度、有机碳含量和断裂系统进行了分析。研究表明,在冲绳海槽西侧及槽底都发育了较厚的上新统和第四系沉积层,上新统厚度约为1000—1500m,第四系厚约为1000—3500m,其中海槽南段存在巨厚的第四系,而且冲绳海槽西侧陆坡沉积物中有机质含量高达0.75%—1.25%,并且沉积速率高达10—40cm/ka,有利于有机质的保存和转化。陆坡发育有与海槽走向一致的NE-SW向断裂系统,以及横切海槽的一系列NW-SE向水平错动扭性断裂系统,其中NE-SW向断层在海槽南段方向变为NEE-SWW,这些断裂系统为烃类气(流)体的运移创造了有利条件。因此,在冲绳海槽西侧陆坡发育的海底峡谷、滑塌体、断块隆脊、泥底辟等特殊地质体与天然气水合物的形成密切相关。 相似文献
20.
Avan N. Antia Bodo von Bodungen Rolf Peinert 《Deep Sea Research Part I: Oceanographic Research Papers》1999,46(12):501
Results are presented from particle flux studies using sediment trap and current meter moorings along a transect at the European continental margin at 49°N within the EU-funded Ocean Margin Exchange (OMEX) project. Two moorings were placed, at the mid- and outer slope in water depths of 1500 and 3660 m, with traps at 600 and 1050 m and at 580, 1440 and 3220 m, respectively. Residual currents at the mid-slope follow the slope contour, whereas seasonal off-slope flow was registered at the outer slope. At 600 m on the slope fluxes are similar to those in the abyssal North Atlantic. The flux of all components (bulk dry weight, particulate organic and inorganic carbon, lithogenic matter and opal) increased with water depth. Highest fluxes were recorded at 1440 m at the outer slope, where off-slope residual currents mediate particle export. The injection of biogenic and lithogenic particles below the depth of winter mixing results in the export of particles from shallower waters. Calculated lateral fluxes of particulate organic carbon exceed the primary flux by over a factor of 2 at 1440 m on the outer slope. Estimated lateral fluxes of suspended particulate matter in the water column and intermediate nepheloid layers at the outer slope are potentially large compared to sinking fluxes measured by sediment traps. A comparison is made of particle flux at three continental margin sites and two sites in the adjacent open North Atlantic, from which it is seen that bulk and organic matter flux increases exponentially with proximity to the shelf break. The percentage contribution of particulate organic carbon to biogenic fluxes increases from a mean of 5.7% in the abyssal N. Atlantic to 13.9% at the continental margins. 相似文献