The clay-rich sediments are overlain by limnic black mud, sandy clay and dark-brown mud-rich peat up to 70 cm thick. During the past 4500 years, 500 cm of low-ash (<5 wt.%), low-sulfur (<0.4 wt.%) woody peat was deposited in narrow (400–700 m), elongate (3 km) tributary valleys of the southern Tasek Bera swamp system. AbstractMany good quality, thick, low-ash Carboniferous, Cretaceous and Tertiary coal deposits have dulling-upward sequences that have been interpreted to be of ombrotrophic, lowland, coastal origin. The acrotelm (top 50 cm) has a low-to-medium ash content (<10 wt.%). With burial, the deposits of southern Tasek Bera Basin would yield a dendritic sediment pattern of sandstone, shale, carbonaceous shale and a dulling-upward, vitrain-rich coal, overlain by carbonaceous shale. The basal 3 m of the peat deposits contain abundant logs and large woody fragments, whereas the top 2 m have less hard wood, but more arborescent fragments of palmae, such as roots from Pandanus atrocarpus.
However, most modern coastal ombrotrophic deposits would yield “all bright” coal seams. Другие схемы и сервис-мануалы, а также книги, журналы и сборники вы можете скачать в нашей Бесплатной технической библиотеке. Peat accumulation in the Tasek Bera Basin began in Mid-Holocene time.
New evidence from peat deposits of the southern intermontane Tasek Bera Basin, Western Malaysia, reveals that thick, low-ash, low-sulfur peat may originate in narrow tributary valleys with moderately steep flank gradients. The ash content of the mud-rich peat is as high as 31 wt.%. The high-ash peat is overlain by low-ash, sapric to hemic peat up to 5 m thick. Previous studies of potential modern analogues for thick, dulling-upward coal sequences have focused on tropical, ombrotrophic coastal peats. Before onset of peat accumulation, a thick (>40 cm) white, fluvial silty clay with wood fragments was deposited. These deposits may be favorable precursors to dulling-upward coals, in that they contain high wood and low-ash content at depth and medium wood and slightly increasing ash content in the upper parts. Events Join Us! It’s Spring and there are a ton of fun events planned to get you moving, keep you motivated, and inspire you to help kids at CHOP!