Factors controlling growth of modern tufa: results of a field experiment
Factors controlling growth of modern tufa: results of a field experiment
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DOI：
10.1144/sp336.8
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发表时间：
2010-01-01
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影响因子：
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通讯作者：
Gradzinski, Michal
中科院分区：
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作者：
Gradzinski, Michal
在斯洛伐克和波兰的四个地点进行了实地试验，以确定影响现代凝灰岩生长速度和质地的因素。在每个研究点放置两对片剂，每对由石灰石片剂和铜片组成。每个研究中心每3或4个月更换一对，而第二对则保留约14个月。在放置前和取出后称量每片石灰华，以确定石灰华生长量，发现石灰华生长速率取决于SIcalc。虽然石灰华在石灰岩片上的沉积速度比在铜片上快得多。这一结果表明，微生物对石灰华的更有效生长至关重要。在快速流动的水体中，凝灰岩的生长速率比在附近缓慢流动的水体中要高，快速生长的凝灰岩具有晶体结构或由高度结壳的藻丝组成。后一种结构是由于微生物的快速生长，由方解石在其细胞上的快速结晶所迫使。缓慢生长的凝灰岩主要表现为泥晶结构。凝块泥晶灰岩和大量硅藻主要在冬季形成，而结壳藻丝是春季和夏季生长的典型特征。
A field experiment was performed at four sites in Slovakia and Poland in order to identify factors that influence the growth rate and textures of modern tufas. Two pairs of tablets were placed at each study point, every pair consisting of a limestone tablet and a copper tablet. One pair at each site was changed every three or four months, while the second pair was left for approximately 14 months. Each tablet was weighed before placing and after removal to find the amount of the tufa growth.Tufa growth rate was found to depend on SIcalc. of parent water, though deposition of tufa on limestone tablets was substantially faster than on copper tablets. This result indicates that micro-organisms are essential for more efficient growth of tufa. Tufa growth rate was higher in fast-flowing water than in nearby sluggish flow settings.Fast-growing tufa has crystalline texture or consists of highly encrusted algal filaments. The latter texture is due to faster growth of micro-organisms, forced by rapid crystallization of calcite on their cells. The slow-growing tufa exhibits mainly micritic textures. Clotted micrite with numerous diatoms forms mostly in winter, while encrusted algal filaments are typical for spring and summer growth.