Fig. 2.

Records of δ¹¹B, δ¹⁸O, TOC, and CaCO₃ changes in the Lop Nor profile. Representative photos show lithological changes mainly from lacustrine bluish gray argillaceous limestone to fluvial-eolian brown/red clayey silt, as shown in the lithological column with visual colors indicated (15). High levels and large fluctuations of proxy values occurred only before ∼4.9 Ma, and since then, those remain low and within a small range, largely similar to modern conditions. The transition from episodic occurrences of lacustrine phases to prevailing desert environments thus appears to be permanent and irreversible.