Microbial mats are layered consortia of microorganisms colonizing surface sediments that alter their physical and chemical characteristics. The northern Patagonia coastline (Argentina) includes gravel deposits (termed rodados Patagónicos) accumulated during the Pleistocene and Holocene by high-energy hydrodynamic processes. In this area, surface sediments in a relict tidal channel (Paso Seco; 40° 38′ 27″ S, 62° 12′ 55″ W) are extensively colonized by microbial mats, appearing to overgrow exposed gravel deposits. To date, such substrates have not been reported as suitable for the development of microbial mats. The objectives of this paper are: 1) to describe the mechanisms of microbial baffling, trapping, and binding of sedimentary particles, and biostabilization that enable epibenthic microbial mats to develop on gravel substrates, 2) to relate microbial mat growth to a variety of hydrodynamic conditions, and 3) to describe resulting microbially induced sedimentary structures (MISS). Our hypothesis is that the alternation of episodic seawater flooding, stagnation, and draining with subsequent subaerial exposure and desiccation are the controlling factors for mat development on gravel. Once stagnant, mud-size sediment particles settle from suspension. At the same time, an initial biofilm may become established on the bottom, using the fine-grained material as substrate. Subsequently introduced particles are baffled, trapped, and bound into the developing biofilm matrix. During the Austral winter comparatively higher values for chlorophyll a and organic matter point towards increased growth of the microbial mat during this season. With increasing coherence, the developing microbial mat may encroach onto individual pebbles, ultimately engulfing them. Eventually, a mature, epibenthic microbial mat levels the sedimentary surface. Hydrodynamic reworking during flooding produces MISS such as mat chips and flipped-over mats.

中文翻译：

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现代砾石沉积物在硅质碎屑海岸环境中的微生物垫定殖

微生物垫是微生物的分层聚生体，它们在表面沉积物中定殖，改变它们的物理和化学特性。巴塔哥尼亚北部海岸线（阿根廷）包括在更新世和全新世期间通过高能水动力过程积累的砾石沉积物（称为 rodados Patagonicos）。在该区域，残留潮汐通道（Paso Seco；40° 38' 27" S，62° 12' 55" W）中的表层沉积物被微生物垫广泛定殖，似乎长满了裸露的砾石沉积物。迄今为止，尚未报道此类底物适用于微生物垫的开发。本文的目的是：1）描述微生物阻隔、捕获和沉积颗粒结合的机制，以及使表层底栖微生物垫能够在砾石基质上发育的生物稳定性，2) 将微生物垫生长与各种流体动力学条件联系起来，以及 3) 描述由此产生的微生物诱导的沉积结构 (MISS)。我们的假设是，间歇性海水泛滥、停滞和排水的交替以及随后的地面暴露和干燥是砾石上垫层发育的控制因素。一旦停滞，泥浆大小的沉积物颗粒就会从悬浮液中沉淀下来。同时，使用细粒材料作为基底，可能会在底部建立初始生物膜。随后引入的颗粒被挡住、捕获并结合到发展中的生物膜基质中。在南方冬季，相对较高的叶绿素 a 和有机物值表明该季节微生物垫的生长增加。随着连贯性的增加，正在发育的微生物垫可能会侵占单个鹅卵石，最终将它们吞没。最终，一个成熟的表层底栖微生物垫使沉积表面平整。洪水期间的流体动力返工会产生 MISS，例如垫子碎片和翻转垫子。