人类在东北亚的最早出现

<正>在人类演化研究中,不同地区早期人类及石器技术的年代问题一直是争论的焦点。对华北泥河湾盆地的小长梁和洞沟这两个平行的湖相沉积剖面作了详细的磁性地层学研究,为20多年前在这里发现的旧石器进行了精确定年。古地磁结果表明,小长     

The earliest cylinder seal in the Arabian Peninsula

A cylinder seal of Late Uruk (late fourth millennium BC) type from Abu Dhabi is presented and analysed. Comparisons with excavated finds from elsewhere in the Near East are discussed. An inventory of cylinder seals from sites in the UAE and the Sultanate of Oman shows that cylinder seal use, while not unknown in the region, was never very great. The ways in which the seal may have arrived at its eventual place of discovery are described and the significance of the seal is assessed.     

In the beginning: Marhashi and the origins of Magan's ceramic industry in the third millennium BC

Ceramics from the Jiroft plain in southeastern Iran are compared with material of Umm an-Nar-type dating to the mid- and late third millennium BC in the Oman Peninsula. Technological and stylistic comparisons suggest the strong possibility that potters from the Iranian side of the Straits of Hormuz may have been the instigators of Magan's earliest ceramic industry.     

Basin‐scale fluid movement patterns revealed by veins: Wessex Basin,UK

Calcite veins at outcrop in the Mesozoic, oil‐bearing Wessex Basin, UK, have been studied using field characterization, petrography, fluid inclusions and stable isotopes to help address the extent, timing and spatial and stratigraphic variability of basin‐scale fluid flow. The absence of quartz shows that veins formed at low temperature without an influence of hydrothermal fluids. Carbon isotopes suggest that the majority of vein calcite was derived locally from the host rock but up to one quarter of the carbon in the vein calcite came from CO₂ from petroleum source rocks. Veins become progressively enriched in source‐rock‐derived CO₂ from the outer margin towards the middle, indicating a growing influence of external CO₂. The carbon isotope data suggest large‐scale migration of substantial amounts of CO₂ around the whole basin. Fluid inclusion salinity data and interpreted water‐δ¹⁸O data show that meteoric water penetrated deep into the western part of the basin after interacting with halite‐rich evaporites in the Triassic section before entering fractured Lower and Middle Jurassic rocks. This large‐scale meteoric invasion of the basin probably happened during early Cenozoic uplift. A similar approach was used to reveal that, in the eastern part of the basin close to the area that underwent most uplift, uppermost Jurassic and Cretaceous rocks underwent vein formation in the presence of marine connate water suggesting a closed system. Stratigraphically underlying Upper Jurassic mudstone and Lower Cretaceous sandstone, in the most uplifted part of the basin, contain veins that resulted from intermediate behaviour with input from saline meteoric water and marine connate waters. Thus, while source‐rock‐derived CO₂ seems to have permeated the entire section, water movement has been more restricted. Oil‐filled inclusions in vein calcite have been found within dominant E‐W trending normal faults, suggesting that these may have facilitated oil migration.