Retrieving "Black Shale" from the archives

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1. Cretaceous Period

   Linked via "black shales"

   The Cretaceous climate was globally warm, lacking polar ice caps for most of its duration. Proxies suggest that mean annual global temperatures were perhaps $10^\circ\text{C}$ higher than present-day averages [8]. Atmospheric $\text{CO}_2$ concentrations are estimated to have fluctuated between $1000$ and $2000$ parts per million ($\text{ppm}$), contributing to a powerful greenhouse effect maintained partly by volcanic outgassing along the newly formed spreading centers …

2. Ore Deposits

   Linked via "black shale"

   These deposits form directly from cooling and crystallizing igneous rocks. Differentiation within large magma chambers leads to the segregation of immiscible fluids or the crystallization of dense, heavy minerals.
   Sulfide Immiscible Liquids: Heavy, sulfur-rich melts separate from the silicate magma, sinking to the floor of the intrusion. These typically host platinum-group elements (PGEs) and [nicke…