PRE-EVENT FIELD TRIP

AMAZONAS RIVER AND THE “SANOZAMA” SYSTEM: FROM PROTO-AMAZON TO THE MODERN FLUVIAL SYSTEM (AMAZON, NORTH BRAZIL)

Leaders: AFONSO NOGUEIRA (UFPA), LUIZ SATURNINO (UnB), NAZIANO FILIZOLA (UFAM)

Description:
Participants in this fieldtrip will explore the evolution of the Amazonas River system in the central Amazon region, between Manaus and Itacoatiara, in the Amazonas state, with a focus on sedimentological and geomorphological aspects of fluvial deposits exposed along river margins. The excursion will include visits to key outcrops, where participants will examine fluvial bars and associated depositional features in one of the largest river systems on Earth.

The fieldtrip will provide a unique opportunity to investigate the long-term evolution of the Amazonian drainage system through the analysis of three major stratigraphic units bounded by lateritic crusts. The Alter do Chão Formation (Cretaceous), also referred to as the “Proto-Amazonas”, records palaeocurrent directions to the west and is interpreted as evidence of a paleo-river system flowing in the opposite direction to the modern Amazonas River, commonly referred to as the “Sanozama” system. The Novo Remanso Formation (Miocene) represents a stage in which the Amazonas River was still predominantly influenced by cratonic sources, prior to significant Andean uplift, as indicated by sediment provenance dominated by contributions from the Amazon Craton. The Içá Formation (Pleistocene) documents more recent stages of fluvial evolution leading to the establishment of the modern Amazonas River.

Participants will analyze sedimentary structures, facies arrangements, and bar morphologies, linking these observations to changes in sediment supply, tectonic controls, and drainage reorganization through time. The fieldtrip will emphasise discussions on the transition from the westward-flowing “Sanozama” system to the present eastward-flowing Amazonas River, highlighting its significance in South American palaeogeography.

In addition to the geological aspects, the fieldtrip will take advantage of the infrastructure and regional importance of Manaus and surrounding towns to explore the interactions between fluvial systems and human activities. Discussions will address biodiversity and the role of the Amazonas River and its tributaries in local livelihoods, including subsistence practices, food production, economic activities, and transportation.

Boat-based transportation, provided by the Brazilian Geological Survey, will allow access to outcrops and fluvial features along the river margins, ensuring close observation of key sedimentological, geomorphological and socioeconomic elements.

Logistics/recommendations:
The fieldtrip will start in Manaus, a major metropolis in the Amazon region, where participants should arrange their own travel. The excursion will proceed by boat along the Amazonas River toward Itacoatiara, with stops at selected outcrops along the river margins.

Weather conditions in the region are typically hot and humid, and participants are advised to bring lightweight clothing, sun protection, and rain gear. Field activities will involve short walks on sandy and possibly muddy terrain; appropriate footwear is recommended.

The price includes:

· Boat transport;

· 2x packed lunches;

The price does not include:

· Flight tickets;

· Cancellation insurance;

· Accommodation.

Dates: in progress (2 days)

Participants (max.): in progress

Cost: in progress