Physical and Chemical Evaluations of Diamonds and Their Mineral Inclusions from Kimberlite in the Colorado-Wyoming State Line District

科罗拉多-怀俄明州界线地区金伯利岩中钻石及其矿物包裹体的物理和化学评价

• 批准号: 8817024
• 负责人: Malcolm McCallum
• 金额: $ 5.14万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-01-01 至 1991-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8817024&HistoricalAwards=false
• 关键词: Physical; Chemical; Evaluations; Diamonds; Their

Diamonds in kimberlite apparently reflect physiochemical conditions associated with ancient mantle processes. Chemistries of diamond and of included mineral grains are indicative of crystallization environments (e.g. peridotitic vs. eclogitic affinity), and P-T equilibration values can be calculated from some of these data. Parcels of diamonds from all but two recovery sites in the Colorado-Wyoming State Line Kimberlite District are available for study and a detailed physical and chemical evaluation is proposed. The State Line diamonds constitute the largest and only known comprehensive assemblage of diamonds in North America that represents an entire kimberlite field. Determination of the major physical properties (particularly those related to resorption and deformational processes) of these diamonds will permit evaluation of growth environment(s) and changes that may have occurred during and/or after emplacement of host kimberlite. Supporting information will be derived from diamond chemistry (trace elements and C isotopes) and chemistry of included minerals. These data will be utilized to assess diamond genesis models and petrologic models of the upper mantle under the southern Rocky Mountains. Special attentian will be directed toward the problem of a suggested relationship between eclogitic affinity diamonds and subducted oceanic crust.

金伯利岩中的钻石显然反映了与古代地幔过程有关的物理化学条件。金刚石和包裹体矿物颗粒的化学成分指示了结晶环境(例如橄榄岩与榴辉岩的亲和力)，P-T平衡值可以从其中的一些数据计算出来。科罗拉多州-怀俄明州金伯利特区除两个采矿点外，所有采矿点的钻石包裹都可供研究，并提议进行详细的物理和化学评估。国家界线钻石是北美最大也是唯一已知的钻石综合集合体，代表了整个金伯利岩区。确定这些钻石的主要物理性质(特别是与吸收和变形过程有关的性质)将有助于评估生长环境(S)以及在寄主金伯利岩侵位过程中和(或)之后可能发生的变化。辅助信息将来自钻石化学(微量元素和碳同位素)和所含矿物的化学。这些数据将用于评估落基山脉南部上地幔的钻石成因模型和岩石学模型。将特别关注榴辉亲和性钻石和俯冲洋壳之间的关系问题。