The Orocaima SLIP consists of an association of acid-intermediate volcanic-plutonic rocks. The volcanic rocks were generated in explosive eruptions through low eruptive columns, probably associated with fissural volcanism in the north of the Amazonian Craton, Brazil, between 2.0 and 1.98 Ga. It generated ignimbrites, whose facies (volcanic breccia rich in lithic, lapilli-tuff and lithic lapilli-tuff) show the proximity of the source. The extensive area of ca. 200.000 km² of ignimbrite, rhyolite and dacite deposits, as well as the age range (2.0–1.98 Ga) and geochemical signatures suggest that the Orocaima volcano-plutonism may correspond to one of the oldest silicic LIPs in the world. The silicic volcanism is essentially subaerial and characterized by high-grade ignimbrites (densely welded) and subordinate lava, the ages of which indicate the longevity of the volcanic event in the Orosirian. They are included in the Surumu Group and comprise rocks with high-K calc-alkaline affinities and were emplaced in a subduction-related setting, similar to the rocks that extend through Venezuela, Guyana and Suriname (Cuchivero-Surumu-Iwokrama-Dalbana metavolcanic belt - CSID). The occurrence of mafic fragments disseminated in volcanic and granitic rocks in the north of Roraima, Brazil and in other segments of the CSID belt suggests the coexistence of acid and basic magmas. Except for one sample (ε_Nd(t) = -2.3), the Nd isotopic data of analyzed Surumu Group volcanic rocks yielded positive ε_Nd(t) values (0.5–4.48; T_DM = 2.0–2.47 Ga), suggesting generation from magmas derived from the mantle or from the melting of new juvenile crust. The Orocaima volcanism bears no evidence of involvement of Archean sources in the generation of the rocks. Thus, the Orocaima volcano-plutonism may represent one of the most significant ignimbrite eruption events during the Palaeoproterozoic in the world.

Orocaima SLIP 由酸性-中级火山-深成岩组合组成。火山岩是通过低喷发柱在爆炸性喷发中产生的，可能与巴西亚马逊克拉通北部的裂隙火山活动有关，在 2.0 到 1.98 Ga 之间。和石质 lapilli-tuff) 显示源的接近度。广阔的面积约。200.000 公里²熔凝灰岩、流纹岩和英安岩沉积物以及年龄范围 (2.0-1.98 Ga) 和地球化学特征表明 Orocaima 火山-深成岩作用可能对应于世界上最古老的硅质 LIP 之一。硅质火山活动基本上是地下的，其特征是高品位的熔凝灰岩（密集熔结）和次要熔岩，其年龄表明奥罗斯纪火山事件的寿命。它们被包括在苏鲁木群中，由具有高 K 钙碱性亲和力的岩石组成，并被置于与俯冲相关的环境中，类似于延伸穿过委内瑞拉、圭亚那和苏里南的岩石（Cuchivero-Surumu-Iwokrama-Dalbana 变质火山带） - CSID）。分布于罗赖马北部火山岩和花岗岩中的镁铁质碎片的出现，巴西和 CSID 带的其他部分表明酸性和碱性岩浆共存。除了一个样品（ε_Nd (t) = -2.3)，经分析的苏鲁木群火山岩的 Nd 同位素数据产生了正 ε _Nd (t) 值（0.5-4.48；T _DM  = 2.0-2.47 Ga），表明来自地幔或来自新幼壳的融化。Orocaima 火山作用没有证据表明太古代源参与了岩石的生成。因此，Orocaima 火山-岩体作用可能代表了世界上古元古代期间最重要的火山灰喷发事件之一。