Scholarlink

<p>Potassium-rich evaporites are economically valuable sedimentary resources frequently associated with salt diapirs, recognized as strategic mineral deposits due to their critical role in fertilizer production and modern agriculture. The Azerbaijan–Zanjan–Hamedan Basin in northwestern Iran hosts numerous evaporite formations, several of which contain potash-bearing sequences. In this study, we investigate the Aji–Chai and Ghareh–Aghaj deposits using subsurface density distributions derived from gravity data inversion. Building on previous studies of salt diapirs in this basin, we introduce several methodological enhancements aimed at improving the geological reliability of density contrast models obtained from mixed <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(L_p\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>L</mi> <mi>p</mi> </msub> </math></EquationSource> </InlineEquation>-norm inversions. First, we examine the effectiveness of the depth weighting exponent (<InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\beta\)</EquationSource> <EquationSource Format="MATHML"><math> <mi>β</mi> </math></EquationSource> </InlineEquation>), which compensates for the rapid decay of potential fields with depth. We demonstrate that the influence of <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\beta\)</EquationSource> <EquationSource Format="MATHML"><math> <mi>β</mi> </math></EquationSource> </InlineEquation> depends on the chosen regularization scheme: An exponent that performs well in sparsity-promoting inversion for a single anomalous source may not yield satisfactory results under traditional Tikhonov regularization. Thus, selecting an appropriate depth weighting exponent is critical for accurately reconstructing target geometries in 3D gravity inversion. Second, recognizing the significant influence of the reference model on inversion outcomes, we explore two distinct scenarios: (1) applying equal weights to all smallness and smoothness components and (2) reducing the weight of the smallness term to <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(1\%\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>1</mn> <mo>%</mo> </mrow> </math></EquationSource> </InlineEquation> of each smoothness term, thereby promoting a more data-driven solution. These strategies are validated using synthetic models representing typical salt dome geometries, including dipping and vertical prisms. By systematically testing a range of depth weighting exponents under both scenarios, we identify optimal configurations for reliable model recovery, which are then applied to field data. The inversion results show that the Aji–Chai salt dome extends approximately 100&#xa0;m vertically, dips eastward, and shows no clear evidence of structural control on salt emplacement. In contrast, the Ghareh–Aghaj salt dome exhibits a significantly greater vertical extent of approximately 220&#xa0;m and is situated within a northeast–southwest-trending anticline.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Improved Salt Dome Imaging Through Mixed \(L_p\)-Norm Regularized Gravity Inversion: Insights from Northwest Iran

  • 期刊论文

  • 发表日期：

    2026年7月7日

查看全文
  • Bardiya Sadraeifar,
  • Reza Ghanati,
  • Rezvan Soltanabadi,
  • Mojtaba Hosseini

摘要

Potassium-rich evaporites are economically valuable sedimentary resources frequently associated with salt diapirs, recognized as strategic mineral deposits due to their critical role in fertilizer production and modern agriculture. The Azerbaijan–Zanjan–Hamedan Basin in northwestern Iran hosts numerous evaporite formations, several of which contain potash-bearing sequences. In this study, we investigate the Aji–Chai and Ghareh–Aghaj deposits using subsurface density distributions derived from gravity data inversion. Building on previous studies of salt diapirs in this basin, we introduce several methodological enhancements aimed at improving the geological reliability of density contrast models obtained from mixed \(L_p\) L p -norm inversions. First, we examine the effectiveness of the depth weighting exponent ( \(\beta\) β ), which compensates for the rapid decay of potential fields with depth. We demonstrate that the influence of \(\beta\) β depends on the chosen regularization scheme: An exponent that performs well in sparsity-promoting inversion for a single anomalous source may not yield satisfactory results under traditional Tikhonov regularization. Thus, selecting an appropriate depth weighting exponent is critical for accurately reconstructing target geometries in 3D gravity inversion. Second, recognizing the significant influence of the reference model on inversion outcomes, we explore two distinct scenarios: (1) applying equal weights to all smallness and smoothness components and (2) reducing the weight of the smallness term to \(1\%\) 1 % of each smoothness term, thereby promoting a more data-driven solution. These strategies are validated using synthetic models representing typical salt dome geometries, including dipping and vertical prisms. By systematically testing a range of depth weighting exponents under both scenarios, we identify optimal configurations for reliable model recovery, which are then applied to field data. The inversion results show that the Aji–Chai salt dome extends approximately 100 m vertically, dips eastward, and shows no clear evidence of structural control on salt emplacement. In contrast, the Ghareh–Aghaj salt dome exhibits a significantly greater vertical extent of approximately 220 m and is situated within a northeast–southwest-trending anticline.