Mineral Vesicles and Chemical Gardens from Carbonate-Rich Alkaline Brines of Lake Magadi, Kenya

Abstract

Mineral vesicles and chemical gardens are self-organized biomimetic structures that form via abiotic mineral precipitation. These membranous structures are known to catalyze prebiotic reactions but the extreme conditions required for their synthesis has cast doubts on their formation in nature. Apart from model solutions, these structures have been shown to form in serpentinization-driven natural silica-rich water and by fluid-rock interaction of model alkaline solutions with granites. Here, for the first time, we demonstrate that self-assembled hollow mineral vesicles and gardens can be synthesized in natural carbonate-rich soda lake water. We have synthesized these structures by a) pouring saturated metal salt solutions, and b) by immersing metal salt pellets in brines collected from Lake Magadi (Kenya). The resulting structures are analyzed by using SEM coupled with EDX analysis, Raman spectroscopy, and powder X-ray diffraction. Our results suggest that mineral self-assembly could have been a common phenomenon in soda oceans of early Earth and Earth-like planets and moons. The composition of the obtained vesicles and gardens confirms the recent observation that carbonate minerals in soda lakes sequestrate Ca, thus leaving phosphate behind in solution available for biochemical reactions. Our results strengthens the proposal that alkaline brines could be ideal sites for “one-pot” synthesis of prebiotic organic compounds and the origin of life.

Plausible Emergence of Biochemistry in Enceladus Based on Chemobrionics

“…Further, for the same reason, we tested various Na 2 CO 3 concentrations from 0.5 to 1 m . It should be noted that such high concentration of carbonates has been found in the soda lakes of Rift Valley in Eastern Africa [21] …”

“…Although we have used relatively high concentration of Na 2 CO 3 to drive the formation of chemical gardens, it should be noted that oceans are not homogeneous and local variations in salt concentrations are very common [5] . Further, in a previous study the same range of concentrations of Na 2 CO 3 were used to simulate Enceladus ocean, [14] while such concentrations have been found in soda lakes on Earth [21] . The pressure at the ocean floor of Enceladus, which is approximately 50 bar, was not taken into consideration for chemical gardens described here.…”

A Comprehensive Methodology for Monitoring Evaporitic Mineral Precipitation and Hydrochemical Evolution of Saline Lakes: The Case of Lake Magadi Soda Brine (East African Rift Valley, Kenya)

“…The early precipitation of calcium carbonate minerals produces the depletion of calcium, which results in a lack of apatite precipitation , and the consequent accumulation of phosphate in soda lakes up to levels relevant to the syntheses of prebiotic biomolecules. Lake Magadi samples were supersaturated with respect to fluorapatite since the beginning of evaporation.…”

Generation of Chemobrionic Jellyfish‐Like Structures That Mechanically Divide and Exhibit Biomimetic “Symbiosis”

“…The result was a growth of a biomimetic hollow plant‐like structure [2] . It is now well‐established that chemical gardens can grow in other than silicate solutions, such as phosphates, borates, carbonates, arsenates etc [1] as well as in an environment with organic chemicals, [3] in natural silica‐rich spring waters [4] and in alkaline brines [5] . The study of chemical gardens has important applications in the hydration of cement, [6] the study of metal corrosion, [7] while they constitute the laboratory analogues of hydrothermal vents [8] .…”