Multiproxy Paleosol Evidence for Jurassic Paleoclimate Fluctuations in the Sichuan Basin, SW China     

LI Jun  WEN Xingyue  PAN Yuanyuan  HUANG Chengmin 《《地质学报》英文版》2022,96(6):2105-2124

Paleoclimate reconstruction of continental environments has been hampered by the limited evidence. A thick sequence of Jurassic continental deposits in the Sichuan Basin, Southwest China yields abundant paleosols that may offer valuable insights regarding Jurassic climate scenarios. A succession of 169 paleosols belonging to Protosols, Calcisols, and Argillisols from 23 detailed stratigraphic sections was recognized and characterized macro- and micromorphologically and assessed for mineral and geochemical compositions. Quantitative paleoclimate reconstructions using bulk geochemical proxies, the depth to and the stable oxygen isotopic composition of paleosol carbonates indicated a predominant alternation of semiarid and arid cool/warm-temperate climatic conditions punctuated by several episodes of subhumid and humid climates that generally prevailed in the Sichuan Basin during the Jurassic. The estimated paleoatmospheric CO2 concentrations (pCO2) from calcic paleosols yielded a low range of ~104 ± 58 to ~610 ± 152 ppmv during the Middle Jurassic. The terrestrial paleotemperature changes in the Sichuan Basin coincided with the pCO2 variations, which probably resulted from global geological events (e.g., volcanic activities, magmatic and oceanic events, and the ephemeral caps development) in the Middle Jurassic. Jurassic climatic fluctuations in the basin were likely attributed to true polar wander due to global plate motion, megamonsoon effect linked to global and regional paleogeography, and regional paleotopography.  相似文献   

吉林双辽地区风沙堆积古温度研究     

李丰江  邓金宪  温泉波  陈广善  李军敏 《地理科学》2004,24(5):616-619

文章根据吉林双辽地区风沙堆积物中的Fe3+/Fe2+值,计算了风沙堆积时的古温度及其变化,结合堆积物的定年数据,建立了该区76.9±6.0～17.8±1.4kaB.P.期间温度波动旋回。结果表明:这一地质时期吉林双辽地区年均温度变化于1.13℃～8.70℃之间,整体较现在为低,应为末次冰期影响所致。该研究得到的松辽平原末次冰期的温度数据,为系统建立松辽平原晚更新世古气候年表提供了重要基础资料。  相似文献   

川东地区古生界主要泥页岩最高古温度特征   总被引：3，自引：0，他引：3       下载免费PDF全文

曹环宇  朱传庆  邱楠生 《地球物理学报》2016,59(3):1017-1029

泥页岩的热演化过程与其经历的古温度史相关,最高古温度决定它的最终热演化程度.本文利用古温标方法恢复了川东地区古生界主要泥页岩层系经历的最高古温度.研究结果表明,它们在距今80—90Ma时达到最高古温度,龙潭组顶面最高古温度150~220℃,龙潭组底面最高古温度160~230℃,龙马溪组顶面最高古温度160~250℃,五峰组底面最高古温度170~260℃,筇竹寺组顶面最高古温度210~320℃,筇竹寺组底面最高古温度210~320℃.各层最高古温度平面展布特征相似,最高温出现在涪陵—丰都一带,向南与向北温度均呈降低趋势,在达州—开江一带局部出现较高温.此外,结合川东地区古热流史分析认为,川东古生界泥页岩热演化过程具有阶段性,现今处于高-过成熟状态,达到最高古温度后生烃作用停止.川东地区经历较高的最高古温度随后快速抬升剥蚀有利于页岩气的成烃与成藏.  相似文献   

黔北下寒武统黑色岩系古地温及其指示意义   总被引：3，自引：0，他引：3  

杨剑  易发成  钱壮志 《矿物学报》2009,29(1)

采用显微光度计测定黔北下寒武统牛蹄塘组黑色岩系固体沥青反射率平均为5.89%,按相关经验公式折算出来的镜质体反射率平均为4.123%,在迈维尔图解、Karwell图解、Hood图解上投点,结合干酪根和孢粉颜色指数法,推断黑色岩系的古地温为60～250℃。结合黄铁矿热电系数法和包裹体均一法测温值,认为黑色岩系属中、低温沉积成岩成矿作用,以低温沉积成岩成矿作用为主。"热"的来源为海底火山喷溢,含矿热卤水提供了丰富的有用元素。黑色岩系有机碳含量高,属好烃源岩,有机质成熟度高,热演化程度高,属过成熟。黑色岩系古地温的研究,对阐明黑色岩系的沉积、成岩和成矿条件具有重要意义。  相似文献   

Deciphering some unique paleotemperature indicators in halite-bearing saline lake deposits from Death Valley, California, USA     

Sheila M. Roberts  Ronald J. Spencer  Wenbo Yang  H. Roy Krouse 《Journal of Paleolimnology》1997,17(1):101-130

Saline lake deposits are arguably the best source of mid- to low-latitude terrestrial paleoclimate data. Alternating clastic sediments and evaporites of different chemical composition have long been recognized as sensitive records of changes in inflow and aridity related to a variety of climate parameters. Several sources of paleotemperature information from a halite-bearing saline lake deposit are described here – pseudomorphs of a cold-temperature evaporite mineral, homogenization temperatures of fluid inclusions in halite, and stable-isotope compositions of fluid inclusions in halite. Examples of these paleoclimate data come from analysis of the lower half of a 185-m core drilled in Pleistocene saline lake deposits at Death Valley, California. Daily and seasonal temperature variations in saline lake waters create conditions for the appearance and disappearance of temperature-dependent mineral phases. In the Death Valley core, hexagonal-shaped halite crystals, probable pseudomorphs of the cold-temperature hydrous mineral, hydrohalite (NaCl2H₂O), provide evidence of brine temperatures below about 0 °C. Homogenization temperatures of fluid inclusions in primary halite offer an actual (not proxy) record of surface-brine temperatures. Samples with primary fluid-inclusion textures are carefully selected and handled, and data are collected from single-phase aqueous-brine inclusions chilled to nucleate vapor bubbles. Temperature variations are observable at scales of individual halite crystals (hours to days), single halite beds (weeks to months or years), and multiples of beds to entire facies (hundreds to tens of thousands of years). A ¹⁸O/D stable isotope record from the minute quantities of brines in fluid inclusions in halite is accessible using a method recently developed at the University of Calgary. The stable isotope record from the Death Valley core, a complex response to climate variables including temperature, humidity, storm patterns or seasons, and inflow sources, compliments and expands the interpretation emerging from the stratigraphy and homogenization temperatures.  相似文献   

镜质组反射率与沉积盆地古地温分析   总被引：3，自引：1，他引：3  

汤达祯 《地学前缘》1995,2(4):181-188

在地质研究与资源勘探中，特别是针对油气生成、运移和保存有关的地热过程分析，镜质组反射率（Ｒ）已被广泛地应用于沉积盆地古地温的确定。本文从Ｒ增值的反应动力学、Ｒ－古地温－受热时间模拟计算、流体扰动对流型热体系中的Ｒ性征及Ｒ古地温分析技术扩展等方面，概括地总结讨论了有关应用现状与理论进展。由于沉积有机质构成及其热反应作用的复杂性，过分简单地将Ｒ与地温值对应的做法已被否定，代之以地质、地球热力学与反应动力学的综合分析。不同源岩中Ｒ增值与热能关系的确定，温度－时间计算方法的改进、异常热背景如对流型热体制的分析以及低成熟与镜质组缺失条件下成熟度参数的Ｒ标定等，将是今后急待解决的主要问题。  相似文献   

Thermal structure and uplift of the Cretaceous Shimanto Belt, Kii Peninsula, Southwest Japan: An illite crystallinity and Mite b_o, lattice spacing study     

M. Aslam  Awan Katsumi  Imura 《Island Arc》1996,5(1):69-88

Abstract Illite crystallinity (IC) and illite b, lattice spacing were measured across the Cretaceous Shimanto Belt, Kii Peninsula, Southwest Japan. For the IC survey, 103 samples of argillaceous rocks were analyzed from the central area and the western area of the belt. Values of IC (Kubler Index) vary between 0.28 and 0.71 Δ°2θ and indicate diagenetic and anchizone metamorphism respectively. The IC distribution reveals two contrasting patterns of thermal maturity. The Hanazono Formation, exposed in the northern area of the belt, generally dips north, but IC values increase systematically from 0.28 Δ°2θ in the north to 0.54 Δ°2θ in the south and indicate an inverted thermal structure. Values in other formations vary widely in the southern area of the belt ranging between 0.45 and 0.71 Δ°2θ, but the values do not show any systematic change from north to south and on average remain almost constant. Illite b_o, lattice spacing values for 56 samples vary between 9.006 and 9.041 Å corresponding to intermediate pressure conditions of the metamorphic facies. These values, combined with paleotemperatures estimated from IC, indicate paleogeothermal gradients of 22 and 31°C/km for the northern and southern areas of the belt, respectively. The inverted thermal structure of the Hanazono Formation, together with a lower paleogeothermal gradient, possibly is a result of the subduction of a relatively cold oceanic plate during the Late Cretaceous. The higher geothermal gradient could be a product of late thermal overprinting caused by the later subduction of a comparatively younger and hotter oceanic plate during the Eocene.  相似文献   

福建宁化天鹅洞石笋年代和古温度   总被引：9，自引：4，他引：9  

李平  文启彬 《沉积学报》1996,14(1):149-155

石笋的实测年龄和δ18Ｏ的变化同深海岩芯Ｖ２８-２３８对比相吻合，大于２５万年前生长，１．８万年后停止，属中更新世产物，该区和全球古气候变化同步。同台湾海峡、中国南海古环境相同。δ13Ｃ的变化在δ13Ｏ７-６、５-４、３-２段界期有明显的不同，对温度变化和年代划分亦有参考价值。  相似文献   

利用干酪根热解动力学模拟实验研究塔里木盆地下古生界古地温   总被引：9，自引：0，他引：9  

解启求  周中毅 《地球科学》2002,27(6):767-769

通过热解动力学模拟实验，对塔里木盆地塔参1井奥陶系干酪根的热演化过程进行了模拟，以此基础上利用KINETICS软件求取干酪根镜质体反射率（R0）的生成动力学参数，并结合塔参1井的沉积埋藏史，计算塔参1井寒武－奥陶系的古地温，这对于研究塔里木盆地下古生界高过成熟烃源岩的古地温是一种新方法。  相似文献   

Post‐orogenic thermal history and exhumation of the northern Appalachian Basin: Low‐temperature thermochronologic constraints     

Chilisa M. Shorten  Paul G. Fitzgerald 《Basin Research》2019,31(6):1017-1039

Apatite fission‐track (AFT) thermochronology and (U‐Th)/He (AHe) dating, combined with paleothermometers and independent geologic constraints, are used to model the thermal history of Devonian Catskill delta wedge strata. The timing and rates of cooling determines the likely post‐orogenic exhumation history of the northern Appalachian Foreland Basin (NAB) in New York and Pennsylvania. AFT ages generally young from west to east, decreasing from ~185 to 120 Ma. AHe single‐grain ages range from ~188 to 116 Ma. Models show that this part of the Appalachian foreland basin experienced a non‐uniform, multi‐stage cooling history. Cooling rates vary over time, ~1–2 °C/Myr in the Early Jurassic to Early Cretaceous, ~0.15–0.25 °C/Myr from the Early Cretaceous to Late Cenozoic, and ~1–2 °C/Myr beginning in the Miocene. Our results from the Mesozoic are broadly consistent with earlier studies, but with the integration of multiple thermochronometers and multi‐kinetic annealing algorithms in newer inverse thermal modeling programs, we constrain a Late Cenozoic increase in cooling which had been previously enigmatic in eastern U.S. low‐temperature thermochronology datasets. Multi‐stage cooling and exhumation of the NAB is driven by post‐orogenic basin inversion and catchment drainage reorganization, in response to changes in base level due to rifting, plus isostatic and dynamic topographic processes modified by flexure over the long (~200 Myr) post‐orogenic period. This study compliments other regional exhumation data‐sets, while constraining the timing of post‐orogenic cooling and exhumation in the NAB and contributing important insights on the post‐orogenic development and inversion of foreland basins along passive margins.  相似文献