Mineralogy of nitrogenous guano on the Bounty Islands, SW Pacific Ocean

By far the commonest consituents of insular phosphate deposits are calcium phosphates of the apatite series of minerals, especially varieties that contain structural carbonate in their crystal lattices, e.g. francolite and dahllite. This reflects the fact that the vast majority of described insular phosphate deposits occur in low latitudes, where they have formed, in a tropical environment, by metasomatic replacement of carbonate in coral substrates by phosphate derived either from avian excrement or from phosphorus-enriched lagoonal/lacustrine waters. Thin, recently-formed guano accumulations on islands of the subantarctic Bounty group differ radically in that they consist principally of struvite, a hydrated ammonium magnesium phosphate that is better known as a component of human/mammalian urinary stones and enteroliths, and of bat guano in sheltered speleothems. Apatite occurs only in an accessory role in the Bounty Islands guano. This contrast in mineralogy, and the somewhat anomalous survival of soft, unstable struvite in a totally exposed environment on the Bounty Islands, are attributed to climatic factors and to the nature of the granodioritic rock substrate.     

青藏高原东北部牧羊业的民族学观察及其动物考古学启示

学术界目前已经普遍认识到, 牧羊业是在史前从西亚传入中国的, 青藏高原东北部则被认为有可能是最早接受这些外来物种的区域。然而, 青藏高原大部分地区为特殊的高海拔环境, 气候条件相对恶劣。绵羊是如何传入并适应青藏高原, 及早期的绵羊传入对人类的生活起到了怎样的作用等问题仍然不甚清楚。本研究通过田野调查和访谈的方式, 对青藏高原东北部5个县共10户的牧羊业情况进行了民族学考查。通过这些研究, 发现了青藏高原东北部多样的绵羊品系及其来源、各自的生理特点、适应的不同生态环境及相关的繁殖和蓄养方式。结合调查得到的结果和相关的动物考古学及分子生物学证据发现, 早期绵羊在传入青藏高原高海拔环境的过程中, 需要经历一系列充满挑战性的、对新生态环境适应的过程。因此推测: 人类有意识的将绵羊与本地野生盘羊杂交以得到对高海拔环境的生态适应在这一过程中很可能起到了关键性的作用, 但是具体情况仍需更多动物考古和古DNA研究。本调查所发现的羊群饲养策略对通过动物考古、稳定同位素和古DNA方法研究史前牧羊业有启示、参考和类比作用, 并为今后研究史前牧羊业的跨大陆传播提出应该关注的方向。