Stalagmite δ¹³C_c is one of the most complicated and difficult proxies to interpret in paleoclimate and paleoenvironmental studies because of its sensitivity to various local, regional, and global factors. The significance of the large δ¹³C_c shift (~12‰, vs. VPDB) in several stalagmites from Anjohibe Cave, in northwestern Madagascar, in the late Holocene remains a subject of scientific debate. Although it was assumed to reflect C₃ to C₄ vegetation cover change caused by anthropogenic activities, recent investigations inside the cave, at different locations, revealed a wide δ¹³C_c range of ~10‰ (vs. VPDB), a value that is comparable in its significance to the 12 ‰ temporal variability mentioned above.

In this paper we combine δ¹³C, radiocarbon (¹⁴C), and major and trace elements (MTE) as a proxy to provide additional insights about the non-vegetation drivers of δ¹³C_c in Madagascar. Our study uses two models, the CaveCalc model and the Fohlmeister model, to help our interpretation of the drip water evolution while it percolates down to the cave and precipitates CaCO₃. The radiocarbon results, with values >100 pMC, demonstrate that the bomb peak, i.e., the pronounced increase in atmospheric ¹⁴C signals, are clearly recorded in these modern stalagmites. This suggests that the samples are younger than 1950 CE, and the soil carbon cycling has been fast without significant formation of aged soil organic matter. These radiocarbon results further suggests that stalagmites from Anjohibe Cave might be of use for future efforts to reconstruct past atmospheric ¹⁴C concentrations. Drip water geochemistry, δ¹³C_c and MTE, combined with two model simulations (CaveCalc and Fohlmeister model) suggests that the great δ¹³C_c range is best explained by the combined effects of the DIC residence time in the epikarst that affect the water-rock interaction and the rate of prior carbonate precipitation. This study therefore demonstrated how combined modelling and multi-proxy approaches can advance our understanding of the control mechanisms of δ¹³C_c for paleoclimate research.

石笋δ ¹³ C _c是古气候和古环境研究中最复杂和最难解释的代表之一，因为它对各种局部、区域和全球因素都很敏感。在全新世晚期，马达加斯加西北部 Anjohibe 洞穴的几个石笋中的大 δ ¹³ C _{c位移（~12‰，vs. VPDB）的重要性仍然是科学争论的主题。}虽然假设它反映了人为活动引起的C ₃到 C _{4植被覆盖变化，但最近在洞穴内不同位置的调查显示，δ} ¹³ C _c很宽范围约为 10‰（与 VPDB 相比），其意义与上述 12‰ 时间变异性相当。

在本文中，我们将 δ ¹³ C、放射性碳 ( ¹⁴ C) 以及主要元素和微量元素 (MTE) 结合起来作为替代物，以提供关于马达加斯加δ ¹³ C _{c的非植被驱动因素的更多见解。}我们的研究使用了两个模型，即 CaveCalc 模型和 Fohlmeister 模型，以帮助我们解释滴水在渗入洞穴并沉淀 CaCO ₃时的演变过程。值 >100 pMC 的放射性碳结果表明，炸弹峰值，即大气^{14的显着增加}C 信号，清楚地记录在这些现代石笋中。这表明样品比公元 1950 年更年轻，并且土壤碳循环很快，没有显着形成老化的土壤有机质。这些放射性碳结果进一步表明，来自 Anjohibe 洞穴的石笋可能用于未来重建过去大气¹⁴ C 浓度的努力。滴水地球化学、δ ¹³ C _c和 MTE，结合两个模型模拟（CaveCalc 和 Fohlmeister 模型）表明，巨大的 δ ¹³ C _c范围最好通过影响水岩相互作用和先前碳酸盐沉淀速率的表岩溶中的 DIC 停留时间的综合效应来解释。因此，本研究展示了组合建模和多代理方法如何促进我们对古气候研究中 δ ¹³ C _{c控制机制的理解。}