Late Pleistocene and early Holocene rivers and wetlands in the Bonneville basin of western North America

Field investigations at Dugway Proving Ground in western Utah have produced new data on the chronology and human occupation of late Pleistocene and early Holocene lakes, rivers, and wetlands in the Lake Bonneville basin. We have classified paleo-river channels of these ages as “gravel channels” and “sand channels.” Gravel channels are straight to curved, digitate, and have abrupt bulbous ends. They are composed of fine gravel and coarse sand, and are topographically inverted (i.e., they stand higher than the surrounding mudflats). Sand channels are younger and sand filled, with well-developed meander-scroll morphology that is truncated by deflated mudflat surfaces. Gravel channels were formed by a river that originated as overflow from the Sevier basin along the Old River Bed during the late regressive phases of Lake Bonneville (after 12,500 and prior to 11,000 ¹⁴C yr B.P.). Dated samples from sand channels and associated fluvial overbank and wetland deposits range in age from 11,000 to 8800 ¹⁴C yr B.P., and are probably related to continued Sevier-basin overflow and to groundwater discharge. Paleoarchaic foragers occupied numerous sites on gravel-channel landforms and adjacent to sand channels in the extensive early Holocene wetland habitats. Reworking of tools and limited toolstone diversity is consistent with theoretical models suggesting Paleoarchaic foragers in the Old River Bed delta were less mobile than elsewhere in the Great Basin.     

塔里木盆地满加尔凹陷沉积环境及成盐成钾分析

满加尔凹陷是我国石炭纪主要的的成盐区。在满加尔凹陷内通过收集石油部门地质勘探资料,综合分析了13个钻井资料,发现了膏盐岩层,厚16.5～221m,产状平缓,分布比较稳定。通过对其沉积环境和成矿机理分析,认为满加尔凹陷成盐条件优越,物源丰富,成盐地层为石炭系下统,具有含盐系厚度大、面积广、埋深大、保存条件较好、构造相对稳定等特点,具有成盐成钾的的各种条件,找矿潜力大。     

库车坳陷西段出露盐体的溶解物理模拟

库车坳陷西段古近系库姆格列木群中分布着巨厚的盐岩层,喜山末期构造运动使得大量的盐体在库车前陆褶皱冲断带前缘被逆冲推覆至地表,遭受大气降水的溶解.除了平衡剖面恢复所得出的缩短量之外,盐推覆构造的逆冲推覆距离还应包括溶解盐体的厚度.通过采集研究区出露地表的盐岩样品,进行溶解物理模拟实验,估算自1.64Ma以来,研究区出露盐体的溶解厚度为3.969~14.727km.根据前人利用平衡剖面恢复所计算出该区的盐推覆构造的最大推覆距离为30km以上,从而得出该区的盐推覆构造的最大推覆距离为44.727km以上.     

论中国盐溶角砾岩的特征和分类

中国的蒸发岩矿床非常丰富,与蒸发岩在成因上密切相关的盐溶角砾岩极其发育。本文简述了中国盐溶角砾岩的分布,总结了盐溶角砾岩的一般特征,划分出盐溶角砾岩的主要类型,探讨了盐溶角砾岩与盐泉的关系。     

西藏扎布耶碳酸盐型盐湖卤水相化学研究

中国盐湖资源丰富,且水化学类型齐全。西藏扎布耶盐湖位于西藏高原腹地,该湖卤水水化学类型为碳酸盐型,已处于盐湖演化晚期,是一个固液共存的盐湖矿床,具有很好的工业开发价值。笔者分别在15℃、25℃下对该卤水进行了等温蒸发实验,研究了在此两个温度下卤水中各元素富集行为和盐类矿物析出规律。并通过讨论其与国内外碳酸盐型和硫酸盐型锂盐湖的卤水蒸发路径和矿物析出异同,指出扎布耶盐湖具有其独特的卤水蒸发析盐路径。在本实验中低温有利于卤水中锂的富集,而高温有利于硼的富集,碳酸锂和钾盐交叉析出,低温时钾的矿物主要为钾石盐,高温时主要为钾芒硝,高温有利于获得高品位的碳酸锂混盐。     

Fish Remains from Homestead Cave and Lake Levels of the Past 13,000 Years in the Bonneville Basin

A late Quaternary ichthyofauna from Homestead Cave, Utah, provides a new source of information on lake history in the Bonneville basin. The fish, represented by 11 freshwater species, were accumulated between 11,200 and 1000 ¹⁴C yr B.P. by scavenging owls. The ⁸⁷Sr/⁸⁶Sr ratio of Lake Bonneville varied with its elevation; ⁸⁷Sr/⁸⁶Sr values of fish from the lowest stratum of the cave suggest they grew in a lake near the terminal Pleistocene Gilbert shoreline. In the lowest deposits, a decrease in fish size and an increase in species tolerant of higher salinities or temperatures suggest multiple die-offs associated with declining lake levels. An initial, catastrophic, post-Provo die-off occurred at 11,300–11,200 ¹⁴C yr B.P. and was followed by at least one rebound or recolonization of fish populations, but fish were gone from Lake Bonneville sometime before 10,400 ¹⁴C yr B.P. This evidence is inconsistent with previous inferences of a near desiccation of Lake Bonneville between 13,000 and 12,000 ¹⁴C yr B.P. Peaks in Gila atraria frequencies in the upper strata suggest the Great Salt Lake had highstands at 3400 and 1000 ¹⁴C yr B.P.     

Albian extrusion evidences of the Triassic salt and clues of the beginning of the Eocene atlasic phase from the example of the Chitana-Ed Djebs structure (N.Tunisia): Implication in the North African Tethyan margin recorded events, comparisons

In the northern part of Tunisia, close to Testour/Slouguia, new observations and updated biostratigraphy make it possible to highlight the relation between the Triassic saliferous mass and the surrounding Mesozoic beds (T. M.). Near the (T. M.) boundary, the formations observed consist dominantly of Triassic evaporites reworked in the Early and Late Albian deep-water sedimentary deposits. Throughout the studied area, Jurassic rocks are absent. We propose to interpret the Chitana-Ed Djebs structure originally emplaced as gravitational stretch masses in a passive margin in the same way as the salt bodies of widespread salt province in the Gulf of Mexico. A reconstructed schematic position of the Chitana-Ed Djebs salt body displays a scenario of setting of the salt mass on a submarine palaeo-slope. Moreover, the starting clues of the paroxysmal event of the Late Mesozoic tectonic inversion clearly fossilized through the discordance of the Middle Eocene–Early Lutetian limestone on the Albian series.     

Phase Chemistry Study of the Dangxiongcuo Salt Lake Brine:Isothermal Evaporation at 25℃

正Production of lithium carbonate from brines has become the dominate trend in the world from the beginning of this century.Dangxiongcuo,a carbonate-type salt lake,is located in the interior of the Tibetan Plateau,China.As a salt lake deposit,rich in Li,B,K and other useful trace     

Geodynamic evolution of the Salinas de Añana diapir in the Basque-Cantabrian Basin,Western Pyrenees

The Salinas de Añana diapir is located in the Basque-Cantabrian basin part of the great evaporite basin, along with the Gulf of Mexico and the Central European basin, when the fragmentation of Pangea started. The evolution of these basins can only be achieved by understanding the control of salt in the sedimentary and tectonic evolution of these basins.Sedimentation began with clastic Buntsandstein sediments and minor Muschelkalk limestones. Subsequent Keuper evaporites are the bottom of sedimentary cover constituted by Jurassic limestones and marls, a clastic Lower Cretaceous and an alternant limestone and marl Upper Cretaceous, whose deposition has been conditioned by salt tectonics. The emplacement of salt extends from the Aptian until now, favored by the duplication of the salt thickness associated with the thrust of Sierra Cantabria, so it is an excellent example to study changes in the regime of intrusion along the time. The geodynamic evolution of the Salinas de Añana diapir was determined through the interpretation of 45 reprocessed seismic lines, along with information from three wells. Migration of the salt in this diapir, conditioned by N120E and N30E pre-Alpine basement lineations, was determined using time isopach maps of the various rock layers. Vertical evolution of the diapir was determined through the reconstruction of a north-south section at various geologic times by flattening the respective seismic horizons. A minimum of salt flow into the diapir coincides with a minimum rate of sedimentation during the Turonian. Similarly, maximum flows of salt into the diapir occurred during the Coniacian and Lower Santonian and again from the end of the Lower Miocene to the present, coinciding with maximum rates of sedimentation during these times. In the Tertiary, probably during the Oligocene, the diapir was displaced to the south by the Sierra Cantabria thrust, maintaining the contact between the evaporites of diapir and the same evaporites of the lower block. Since the Oligocene, the salts of the lower block migrated towards and into the diapir, deforming the trace of the overthrust.     

兰坪——思茅盆地石盐矿床盐矿物包裹体特征

石盐矿床在蒸发沉积过程中经受环境变化而被改造，兰坪－思茅盆地石盐矿床石盐矿物流体包裹体特征及测温数据证明，该区地壳在喜山期一直处于活动状态，在石盐的成矿、成矿期后都迭加了火山以及构造－热作用。