Gold in the Abitibi greenstone belt in the Superior craton, the most prolific gold-producing greenstone terrane in the world, comes largely from complex orogenic mineralizing systems related to deep crustal deformation zones. In order to get a better understanding of these systems, we therefore combined new magnetic, gravity, seismic, and magnetotelluric data with stratigraphic and structural observations along a transect in the Matheson area of the Abitibi greenstone belt to constrain large-scale geologic models of the Archean crust. A high-resolution seismic transect reveals that the well-known Porcupine Destor fault dips shallowly to the south, whereas the Pipestone fault dips steeply to the north. Facing directions and gravity models indicate that these faults are thrust faults where older mafic volcanic rocks overlie a younger sedimentary basin. The depth of the basin reaches ~2 to 2.5 km between these two faults, where it is interpreted to overlie mafic-dominated volcanic substrata. Regional seismic and magnetotelluric surveys image the full crust down to 36-km depth to reveal a heterogeneous architecture. Three crustal-scale layers include a resistive (10⁴–10⁵ Ωm) upper crust of granite-greenstone rocks, a low-resistivity (~10–50 Ωm) middle crust dominated by granitic plutons for which low resistivity is attributed to the presence of graphite, and a low to moderately resistive (50–1,000 Ωm) and seismically homogeneous lower crust interpreted as granulite gneisses. The significant resistivity transition between upper and middle crust is interpreted to be the result of interconnected micrographite grain coating, precipitated from carbon-bearing crustal fluids emplaced during Neoarchean craton stabilization. A major subvertical, seismically transparent, and extremely low resistive (<10 Ωm) corridor connects the lower and middle crust with the upper crust. The geometry of this low-resistivity feature supports its interpretation as a deep-rooted extensional fault system where the corridor acted as a regional-scale conduit for gold-bearing hydrothermal fluids from a ductile source region in the lower crust to the depositional site in the brittle upper crust. We propose that this newly discovered whole crustal corridor focused the hydrothermal fluids into the Porcupine Destor fault in the Matheson region.

中文翻译：

---

沿阿比比比绿岩带富金马西森断层的地壳尺度地质和断层几何

上级克拉通阿比蒂比绿岩带中的黄金是世界上产金最多的绿岩地体，主要来自与深部地壳变形带相关的复杂造山矿化系统。因此，为了更好地了解这些系统，我们将新的磁、重力、地震和大地电磁数据与沿阿比比比绿岩带马瑟森地区横断面的地层和构造观测相结合，以约束大尺度地质模型。太古代地壳。高分辨率地震剖面显示，著名的豪猪Destor断层向南倾斜较浅，而Pipestone断层向北倾斜较陡。面向方向和重力模型表明，这些断层是逆冲断层，其中较老的基性火山岩覆盖在较年轻的沉积盆地上。盆地的深度在这两个断层之间达到约 2 至 2.5 公里，在那里它被解释为覆盖在以基性岩为主的火山地层上。区域地震和大地电磁勘测可以对深达 36 公里的整个地壳进行成像，以揭示异质结构。三个地壳尺度层包括一个电阻 (10⁴ –10 ⁵Ωm) 花岗岩-绿岩的上地壳，低电阻率 (~10-50 Ωm) 中地壳以花岗岩岩体为主，其低电阻率归因于石墨的存在，以及低至中等电阻率 (50-1,000 Ωm) ) 和地震均质的下地壳被解释为麻粒岩片麻岩。上地壳和中地壳之间显着的电阻率转变被解释为相互连接的微石墨颗粒涂层的结果，这些涂层是从新太古代克拉通稳定过程中沉积的含碳地壳流体中沉淀出来的。一个主要的垂直，地震透明和极低电阻（<10Ωm）的走廊将下地壳和中地壳与上地壳连接起来。这种低电阻率特征的几何形状支持将其解释为一个根深蒂固的伸展断层系统，其中走廊作为区域尺度的通道，将含金热液从下地壳的韧性源区输送到地壳中的沉积地点。脆性上地壳。我们提出，这个新发现的整个地壳走廊将热液流体集中到马西森地区的豪猪德斯托断层中。