关于“峰丛”、“峰林”与“锥状喀斯特”及“塔状喀斯特”涵义的比较和认识

“峰丛”和“峰林”是在中文文献中使用的两种主要的喀斯特地貌术语。而在其他国家,这两种地貌通常被定义为“锥状喀斯特”和“塔状喀斯特”,但峰丛、峰林与锥状喀斯特、塔状喀斯特并不完全相同。中国喀斯特分布广泛,本文把西方和中国的喀斯特专业术语连接起来,能让西方地貌学家更好地了解中国的喀斯特。本文是朱学稳教授近期发表于《中国岩溶》第28卷第2期上的 “我国峰林喀斯特的苦干问题讨论”论文的英文附加篇。 峰丛喀斯特地貌遍及贵州省及其临近省份大部分地区,其锥体石山较爪哇、牙买加和菲律宾群岛的更高更陡。尽管后者为西方所熟知,但贵州的峰丛可以说是峰丛和锥状喀斯特的典型代表。不过广西的峰林仅在中国以外东南亚的小部分地区可以看见。许多被西方认为是塔状喀斯特的地貌并非真正的峰林。问题产生的原因在于西方学者通过山体形状来区分锥状喀斯特和塔状喀斯特,而中国的学者是根据石峰之间是否存在喀斯特平原来区分峰林和峰丛。 峰丛喀斯特是一种发育成熟的石灰岩地貌,具有深厚的包气带、完整的地下排泄系统,以及发育时间长并免遭更新代冰川破坏的山体形貌。峰林喀斯特是一种极端地貌,仅在横向夷平持续时间比较长的特定环境中形成。峰林形成条件是:（1）石灰岩质纯;（2) 石灰岩层厚;（3）喀斯特平原上有冲积层发育;（4）地下水位变化幅度不大;（5）冲积平原有外源沉积物的流入补充;（6）缓慢构造抬升与喀斯特平原表面剥蚀相适应;（7）具有使石灰岩快速溶蚀的炎热湿润气候;（8）周围喀斯特平原下降时,地面蚀低和石灰岩山体边坡后退平衡。如果构造条件合适的话,峰丛可以演化为峰林。但如果有其他因素起作用,峰林和峰丛似乎可以并行发育。二者的起源仍然备受争论,并且峰林的起源恐怕是多种的。建议国际学术文献中应更加广泛地应用“峰丛”和“峰林”术语,“锥状喀斯特”和“塔状喀斯特”则主要用于对形态方面的描述。      

Beyond peasant deforestation: environment and development in rural Jamaica

Jamaica is experiencing one of the highest rates of deforestation in the world, with severe environmental consequences attendant to the loss of its forests. It is also plagued by high levels of poverty, particularly in rural areas. As throughout much of the tropics, impoverished peasant farmers are blamed as the primary agents in Jamaica's forest colonisation. Employing a case study in the Blue Mountains, this paper explores the discord that exists between forest conservation and the development priorities of poor farmers, arguing that this unsustainable dichotomy can only be understood by acknowledging the political economy which constrains peasant agriculture.     

Who moves into, out of and within London?

Summary Eight variables from the 1991 Census 2% Sample of Anonymised Records are used to classify Greater London's population into ten socio-demographic groups. This provides the basis for examining differences between 'types of people' in the extent to which they changed address in the year before the Census and whether they moved into, out of or within London.     

New developments in water efficiency

1Water LossInitiativesUnaccounted-for water(or unbilled water)has beenreceiving newscrutiny at both the state and nationallevels.For years,water conservationeffortsin Europehave emphasized reduction in water loss to a muchgreater extent thaninthe United S…     

贵州贞丰烂泥沟卡林型金矿床含砷黄铁矿Re-Os同位素测年及地质意义

贵州贞丰烂泥沟金矿(现称锦丰金矿)是滇黔桂“金三角”已知最大的卡林型金矿床,矿体赋存于断层破碎带内,最主要的载金矿物是具环带结构的含砷黄铁矿。本文运用Re-Os同位素法对该矿床的9个含砷黄铁矿样品进行了两次测试,成功获得10-9～10-12级Re-Os同位素数据:Re0.1257～1.233ng/g,Os6.75～33.50pg/g,等时线年龄为193±13Ma,反映其成矿时代为早侏罗世。等时线的初始n(187Os)/n(188Os)值为1.127±0.043,指示成矿物质来源于地壳而不是地幔。结合其他资料,初步建立其成矿模式为:盆地流体不断地从沉积物中萃取出包括金在内的成矿组分,形成含矿流体。印支期挤压造山期间,含矿流体沿不整合接触面和同生断层向上运动,造山后的伸展含矿流体进入减压扩容空间沉淀形成超大型金矿床。成矿作用发生在从印支期挤压造山向燕山期伸展转变的构造转换期。该模式与本文得到的成矿年龄和初始比值相吻合。     

The Romanian earthquake of August 30, 1986: A study based on GEOSCOPE very long-period and broadband data

The Romanian earthquake of August 30, 1986 is the second largest intermediate depth event in this area since the worldwide deployment of digital instrumentation, and the first one since the installation of GEOSCOPE network. It offers the unique opportunity to document this well-known but poorly understood zone of deep continental seismicity using high quality teleseismic data in different frequency bands. The source is well constrained both from very-long period surface wave data observed on GEOSCOPE stations and, independently, from body wave modelling at various worldwide stations. The depth obtained is approximately 140 kilometers, the seismic moment, 0.8 10²⁷ dyne-cm and the mechanism from both data sets is very similar to that of the previous 1940 and 1977 Vancrea events, indicating that these events, although having occurred at noticeably different depths, are expressions of the same tectonic process. However, from the detailed study of the source using broadband data, it can be inferred that the source presents much less complexity than the 1977 event.