## 2 Geological Setting  
The Tuli Basin is also known as the Limpopo Basin and it is a small intracratonic east-west trending fault controlled depository with a preserved basin width of about 80 km [2]. The basin forms part of the Limpopo Karoo Supergroup and is deposited at the same time with the Main Karoo Basin, but it is formed as an isolated basin which was fault-controlled from the onset [1]. The Tuli Basin occurs across the borders of South Africa, Botswana and Zimbabwe and is filled with the igneous and sedimentary rocks of the Karoo Supergroup [11]. The sedimentary rocks which are found in the South African part of Tuli Basin consists of different terrigenous elastic and chemical deposits. These rocks are para-breccias, conglo-breccias, conglomerates, sandstone, fine-grained sediments, calcretes and silcretes amongst others [10]. Generally, the word \"Karoo\" is coined from the Main Karoo Basin of South Africa to describe sedimentary fill of all basins of similar age across Gondwana [14]. As reported by [15], the Karoo Basin occupies about 66% of the southern part of the African continent and it is composed mostly sedimentary rocks of Paleozoic age. The Main Karoo Basin of South Africa is a unique type of basin of all the Karoo basins in southern Africa in terms of its thickness and stratigraphy [14]. According to [16], the deposition of the Karoo Supergroup occurred in two broadly different tectonic settings in southern Africa. The Tuli Basin represents the Limpopo area of Karoo-age basins. The Tuli Basin lies at the triple junction of the Zimbabwe, Botswanaan and South African borders and it is generally known that the basin separated from the Tshipise Basin [1]. It has been proposed that the Limpopo area forms the western arm of a failed rift triple-junction [17], which later extended in a north-south direction and from the Save Basin in Zimbabwe to the Lobombo Formation in South Africa [11]. According to [18], the separation is caused by a highly deformed Messina Block in the southern boundary, which could have acted as a positive area during the accretion of the Karoo strata. The Tuli Basin consists of a northern boundary and the boundary is marked by a major ENE trending fault, which is continuous for about 100 km [17]. To date, the tectonic evolution of the Tuli Basin is still debatable, and several models have been used to unravel the tectonic development of the Tuli Basin. One of the tectonic models suggested or provided by [1] shows an ENE trending divergent wrench zone which was responsible for the formation of the Tuli Basin, Nuanetsi Basin and Tshipise Basin (Figure 2). The displacement formed in this model occurred along pre-existing ENE and NE trending faults during the sedimentation of the lower part of the Karoo Supergroup [1]. There is a compressive foreland system, which existed north of the Cape Fold Belt and it was developed in response to the Late Palaeozoic to Early Mesozoic subduction of the Pacific plate [1]. Perhaps, as result of the flexural warping of the lithosphere, the occurrence of three different areas across the distorted profile of the system appears, which include a foredeep, forebulge and back-bulge zone. The Tuli Basin may be recognized with this back-bulge setting based on its distance, which is approximately 1500 km from the northern margin of the Cape Fold Belt and has a relatively thin sedimentary sequence [1]. The area investigated in this study is located in the Tuli Basin, in the north-eastern part of South Africa near Tshipise-Pafuri Basin. Generally, the Tuli Basin trends in the East-West direction and links up with the North-South trending Lebombo Basin, which represents the southern termination of the East African Rift System [19]. In the Tuli Basin, the Madzaringwe Formation, Mikambeni Formation and Flipp Formation are the equivalents of the Ecca Group in the Main Karoo Basin [1] (Figure 3).