AEM Greenland 1997 - Airborne GEOTEM electromagnetic magnetic survey over northern Jameson Land, Central East Greenland

The AEM 1997 survey area (size: 5194 km2) covers the northern portion of the Jameson Land basin which is a thick sequence (up to 17 km) of Palaeozoic and Mesozoic continental and marine sediments invaded by a variety of Tertiary sills, dykes and intrusions. Measurements included acquisition of controlled source electromagnetic data (GEOTEM - time domain EM) and total field magnetic data. The survey was collected by Geoterrex-Dighem Ltd. and financed by the Government of Greenland. Survey lines were oriented east-west at 400 metres interval with north-south directed tie-lines spaced at four kilometres interval. The region has a history of both hydrocarbon and mineral exploration, the latter being the focus of this study. The Blyklippen lead-zinc deposit was commercially mined between 1956-1962 by Nordisk Mineselskab A/S and, although small, is one of the few operating mines in Greenlands history. It is situated within the survey area in the Mesters Vig region. Many other mineral occurrences are known. The Malmbjerg porphyry molybdenum deposit is probably the best known prospect in the area is associated with a Tertiary intrusion and is situated west of the geophysical survey block. Two long reconnaissance lines were flown north of the main survey area to gather some geophysical information for future planning. In 1998 selected anomalies were visited in a follow-up study by GEUS, which concluded that most electromagnetic anomalies are found in relation to thick Tertiary sills intruded into black Jurassic shales and are probaly caused by a combination of contact-metamorphosed, graphite-bearing black shales and massive to semi-massive contact-skarn sulphide/magnetite layers found in these sediments.

1997年航空电磁（AEM）调查区（面积：5194平方千米）覆盖詹姆森陆盆地（Jameson Land basin）北部区域，该盆地发育一套厚达17千米的古生界与中生界陆相、海相沉积序列，且被多套第三纪岩床、岩脉及侵入体穿插侵入。本次调查的数据采集内容包括可控源电磁数据（采用GEOTEM时域电磁（time domain EM）系统）与总场磁测数据。该调查由盖特勒克斯-迪格姆有限公司（Geoterrex-Dighem Ltd.）承揽实施，经费由格陵兰政府（Government of Greenland）提供。主测线为东西走向，线间距400米；南北走向的联络测线线间距为4千米。该区域兼具油气与矿产勘查历史，本次研究以矿产勘查为核心目标。布利克利彭（Blyklippen）铅锌矿床于1956年至1962年间由北欧矿业股份公司（Nordisk Mineselskab A/S）进行商业化开采，尽管规模较小，但仍是格陵兰历史上少数投入运营的矿山之一。该矿床位于调查区内的梅斯特斯维格（Mesters Vig）区域。区内已发现多处其他矿化点。马尔姆贝格斑岩钼矿床（Malmbjerg porphyry molybdenum deposit）或许是该区域最知名的找矿靶区，其与一套第三纪侵入体相关联，位于本次物探调查区块西侧。在主调查区北侧布设了两条长距离踏勘测线，以采集物探数据用于后续规划。1998年，丹麦格陵兰地质调查局（GEUS）开展了后续实地核查工作，对筛选出的物探异常进行了踏勘。该机构得出结论：绝大多数电磁异常均与侵入黑色侏罗纪页岩中的厚层第三纪岩床相关，其成因可能为接触变质含石墨黑色页岩，与赋存于这套沉积层中的块状至半块状接触夕卡岩型硫化物/磁铁矿层共同作用所致。