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首页> 外文学位 >Genesis of the central Tennessee Mississippi Valley-type ore deposits and host rock dolomitization from paleomagnetism.
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Genesis of the central Tennessee Mississippi Valley-type ore deposits and host rock dolomitization from paleomagnetism.

机译：田纳西州中部密西西比河谷型矿床的成因，并由古磁铁矿引起岩石白云石化。

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摘要

Paleomagnetic analysis was conducted on over 1100 specimens from 91 sites collected from a transect of Paleozoic carbonates in Illinois, Kentucky and Tennessee and from mineralization in the central Tennessee Mississippi Valley-type (MVT) zinc-lead ore district. Three characteristic remanence components (ChRMs), termed A, B and C, were observed. The oldest, A, was found in 24 sites of early Paleozoic, fine-grained dolostones from Tennessee and Kentucky. It means pole, after reversal to its antipodal positions, of 126.9{dollar}spcirc{dollar}E, 46.1{dollar}spcirc{dollar}N, ({dollar}delta p = 1.5spcirc , delta m = 3.0spcirc{dollar}) is concordant to the "Kiaman" reserved superchron portion of the Permian apparent polar wander (APW) path for North America. The A ChRM is probably related to the pervasive regional dolomitization that completely surrounds the central Tennessee MVT ore district. The B ChRM, found in 14 sites of MVT ore-stage mineralization, is also dominantly reversed, and gives a pole position of 111.9{dollar}spcirc{dollar}E, 50.5{dollar}spcirc{dollar}N, ({dollar}delta p = 1.7spcirc , delta m = 3.5spcirc{dollar}). It falls on the Permian-Triassic boundary of the North American APW path and is both statistically different from, and younger than, A. Therefore, B is primary and dates the genesis of the mineralization in the central Tennessee ore district. The C ChRM was found at 19 sites in the northwestern part of the transect. Its pole position of 102.7{dollar}spcirc{dollar}W, 80.8{dollar}spcirc{dollar}N, ({dollar}delta p = 5.1spcirc , delta m = 6.4spcirc{dollar}) falls on the present Earth's magnetic pole position and hence it is probably less than 10,000 years old. Successfully defining these three ChRMs, both geographically and temporally, shows that paleomagnetism can be used to date and map fluid-flow events in sedimentary basins.; Bingham statistics were applied to the data for the A and B ChRM directions to examine the process of MVT mineralization. The azimuth and amount of bias of the A and B ChRMs show that host rock remagnetization (and probably pervasive dolomitization) predated mineralization by about 20 Ma and that the ore deposit formed in about 10 Ma. Bingham analysis for five other North American MVT ore districts also shows that the remagnetization of the host rocks was a precursor to the mineralization and that mineralization required {dollar}sim{dollar}25 Ma on average.
机译：在从伊利诺伊州，肯塔基州和田纳西州的古生代碳酸盐样带以及田纳西州密西西比河谷型（MVT）锌铅矿区中的矿化带的91个地点采集的1100多个标本上进行了古磁分析。观察到三个特征剩磁分量（ChRM），分别称为A，B和C。在田纳西州和肯塔基州的古生代，细粒白云岩的24个地点中发现了最古老的A。这意味着在反转其对立位置后，极数为126.9 {dol}} spcirc {dollar} E，46.1 {dollar} spcirc {dollar} N，（{dollar} delta p = 1.5spcirc，delta m = 3.0spcirc {dollar} ）与北美二叠纪视在极地漫游（APW）路径的“凯曼”预留超时部分一致。 A ChRM可能与完全围绕田纳西州MVT矿区的普遍区域白云石化有关。在12个MVT矿石阶段成矿点中发现的B ChRM也主要反转，其极位置为111.9 {dol} scirc {dollar} E，50.5 {dollar} spcirc {dollar} N，（{dollar} Δp＝ 1.7spcirc，Δm＝ 3.5spcirc {美元}。它落在北美APW路径的二叠纪-三叠纪边界上，在统计上既不同于A，也比A年轻，因此B是主要的，并且可以追溯田纳西州中部矿区的成矿作用。 C ChRM在样带西北部的19个地点发现。它的磁极位置102.7 {sp} {dol} W，80.8 {sp} {n} N（{dol} p = 5.1spcirc，delta m = 6.4spcirc {dolal}）落在当前地球的磁极上位置，因此它可能不到10,000年的历史。在地理和时间上成功地定义了这三个ChRMs，表明古磁学可以用来对沉积盆地中的流体流动事件进行测年和测绘。将Bingham统计数据应用于A和B ChRM方向的数据，以检查MVT成矿过程。 A和B ChRM的方位角和偏移量表明，宿主岩的磁化作用（可能是普遍的白云石化作用）比矿化作用早了约20 Ma，矿床形成的时间约为10 Ma。 Bingham对其他五个北美MVT矿区的分析还显示，主岩的再磁化是矿化的先兆，而矿化平均需要25 Ma。

著录项

  • 作者

    Lewchuk, Michael Terry.;

  • 作者单位

    The University of Western Ontario (Canada).;

  • 授予单位 The University of Western Ontario (Canada).;
  • 学科 Geology.; Geophysics.; Geotechnology.
  • 学位 Ph.D.
  • 年度 1996
  • 页码 165 p.
  • 总页数 165
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地质学;地球物理学;地质学;
  • 关键词

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